Health Canada recently announced proposed changes to nutrition labels

Health Canada recently announced proposed changes to nutrition labels as well as the launch of new tools to promote healthier food choices.  The improvements would include a new Nutrition Facts table format and clearer labelling of sugar and serving sizes.  New resources such as the My Food Guide mobile application and the Eat Well Plate will also help Canadians apply the guidance of Canada’s Food Guide to build a healthy meal.  Please pass this information on to your organization’s members or feel welcome to post on your website, share through social media, or on bulletin boards.  

Proposed changes:  

  • Mandating consistent serving sizes will make it easier to compare nutrient contents of similar foods.  The ingredient list on the proposed new label would also be easier to find, read and understand.
  • The addition of a percentage daily value for sugar and the way that it is identified in the list of ingredients will make it easier to understand how much sugar is in a product and what the source is.

New Resources:

  • The  Eat Well Plate helps you follow Canada’s Food Guide when planning and serving meals, showing food group proportions and how to make half your plate vegetables and fruit.
  • The interactive tool My Food Guide customizes Canada’s Food Guide just for you.  You can then print it and stick it on your fridge for quick and easy reference!

Have your say!  To contribute to the consultation on proposed changes to nutrition labels, visit Canada.ca.

Thank you for helping to keep Canadians safe and healthy!

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Health Canada Atlantic Region
www.healthcanada.gc.ca

Santé Canada a annoncé récemment des propositions de modifications à l’étiquetage nutritionnel et le lancement de nouveaux outils pour promouvoir des choix alimentaires plus sains.  Les améliorations proposées incluraient une nouvelle présentation du tableau de la valeur nutritive et l’étiquetage plus clair de la teneur en sucre et de la taille des portions.  De nouvelles ressources telles que l’application mobile Mon Guide alimentaire et l’Assiette Bien manger aideront aussi les Canadiens à préparer des repas santé en appliquant les recommandations du Guide alimentaire canadien.  Nous vous invitons à transmettre ces renseignements à vos membres, à les publier sur votre site Web et dans les médias sociaux, ou encore à les afficher sur vos babillards.

Modifications proposées :

  • Rendre obligatoire l’uniformisation de la taille des portions facilitera la comparaison de la teneur en nutriments d’aliments semblables.  La liste des ingrédients sur la nouvelle étiquette proposée serait aussi plus facile à localiser, à lire et à comprendre.
  • L’ajout d’un pourcentage de la valeur quotidienne pour le sucre et la manière dont il est indiqué dans la liste des ingrédients permettra de comprendre plus facilement la quantité de sucre contenu dans un produit ainsi que sa source.

Nouveaux outils :

  • L’Assiette Bien manger vous aide à suivre la Guide alimentaire canadien lorsque vous planifiez et préparez des repas en présentant les proportions des groupes alimentaires et la façon de remplir la moitié de votre assiette avec des légumes et des fruits.
  • L’outil interactif Mon guide alimentaire permet de personnaliser leGuide alimentaire canadien juste pour vous.  Vous pourrez ensuite l’imprimer et l’afficher sur votre réfrigérateur pour le consulter rapidement et facilement!

À vous la parole!  Afin de contribuer au processus de consultation sur des propositions de modifications à l’étiquetage nutritionnel, visitez le site Web Canada.ca.   
 
Merci de contribuer à la sécurité et à la santé des Canadiens!

Pour vous désabonner de cette liste d’envoi, veuillez simplement répondre à ce courriel en indiquant « Me désabonner » comme sujet.

Santé Canada, Région de l’Atlantique
www.santecanada.gc.ca

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Vitamin E

WHFoods

For serving size for specific foods see the Nutrient Rating Chart.

Basic Description

Vitamin E is a blanket term for eight different naturally occurring nutrients—four different tocopherols and four different tocotrienols. Each of these vitamin E types is considered a fat-soluble antioxidant, and all eight are found in varying degrees in our daily diet. You may sometimes hear all eight molecules being referred to collectively as “tocochromanols.”

The most famous of the vitamin E group is alpha-tocopherol. Both with respect to diet and high-dose supplementation, it is among the most intensely studied of nutrients. This is because its ability to help prevent free radical damage is well documented Public health recommendations for vitamin E are typically measured in milligram equivalents of alpha-tocopherol equivalents, or mg ATE. You will find this abbreviation being used throughout our live website charts.

However, despite the current prominence of alpha-tocopherol in public health recommendations and nutrition research, scientists are also interested in potential health benefits associated with lesser studied members of the vitamin E family, especially the tocotrienols. Like tocopherols (including alpha-tocopherol), tocotrienols are naturally occurring forms of vitamin E. Since they cannot be converted by humans into alpha-tocopherol, the tocotrienols are not considered relevant in meeting vitamin E needs. However, preliminary studies suggest that tocotrienols can provide us with health benefits in a way that is distinct from alpha-tocopherol, as well as other tocopherols. We look forward to future research in this area.

In this introductory description of vitamin E, it is also worth mentioning the unusually confusing nature of its units of measurement. There is really no such thing as “milligrams of vitamin E” since this description fails to explain what forms of the vitamin were considered when making the determination. As mentioned earlier, our website chart present vitamin E data in terms of “mg ATE” which stands for “milligrams of alpha-tocopherol equivalents.” However, other types of equivalents can be used in presenting vitamin E data. For example, equivalents of d-alpha-tocopheryl acetate and equivalents of d-alpha-tocopheryl succinate can be used. (These two chelated, synthetic forms of vitamin E are frequently found in dietary supplements due to their longer shelf life).

While many of the World’s Healthiest Foods are rich in vitamin E, we see that average U.S. adults fail to come close to a minimal requirement for this important nutrient. Below, we’ll give you some guidance to help you chose foods rich in vitamin E that will better help you meet your daily needs.

You’ll have a number of foods to choose from to build a menu that is rich in vitamin E. We list seven of the World’s Healthiest Foods as excellent sources of vitamin E. Another six foods rate as very good sources, while twelve foods are listed as good.

Role in Health Support

Protection Against Free Radical Damage

Vitamin E is a potent antioxidant. Because it is fat soluble, we see it offer protection against damage to the fats that line the outside of every cell of our body.

When the fats in our membranes become damaged, important cell functions become compromised. Based on this important mechanism, researchers have studied whether diets low in vitamin E are associated with many diseases associated with aging.

We also see vitamin E protect fats from free radical damage before we eat them. We’ll talk about the role of vitamin E in protecting foods during storage below in the Impact of Cooking, Storage, and Processing section.

Protection Against Heart Disease

Vitamin E helps protect LDL cholesterol (sometimes referred to as “bad” cholesterol) from free radical damage. Free radical damage typically involves an unwanted interaction with a reactive oxygen-containing molecule. When vitamin E is deficient—and under some other circumstances as well—it is possible for LDL cholesterol to become insufficiently protected and damaged by oxygen. When damaged in this way, the LDL cholesterol is often referred to as “oxidized LDL.” If the process continues, it is possible for oxidized LDL to accumulate in blood vessel walls and create the early stages of hardening of the arteries (atherosclerosis).

Diets rich in vitamin E from vegetables, fish, and plant oils—like the Mediterranean diet for example—have been linked to cardiovascular prevention in large health surveys. Understand, though, that the potential benefits of this diet are not limited to or fully explained by vitamin E, and that dietary supplements of vitamin E (in comparison to vitamin E in food) have not demonstrated the same sort of preventive benefit that researchers hoped to see.

Summary of Food Sources

Of our seven excellent sources of vitamin E, five are green leafy vegetables. Followers of our WHFoods site will probably not be surprised by this—green leafy vegetables score well as sources of many different nutrients. With respect to vitamin E, their combination of nutrient richness and low calories is very compelling to our rating system. Expect each serving of greens to contain about 15 to 25% of your daily requirement.

Outside of greens, the foods with the most vitamin E tend to be high fat foods. These include nuts, seeds, extracted oils, and fatty fish. The amount of vitamin E per serving of nuts or seeds can vary widely, but you should expect to receive at least about 10% of your daily need, and sometimes as much as 80% (as we see with sunflower seeds).

Many oil rich-plants give us good amounts of vitamin E. These include olives and avocados, both of which provide between 10-15% of your daily need. Because these oily foods contain more calories, we rate them as good rather than very good or excellent sources. Still, we encourage using these plants or plant oils to help provide vitamin E.

We see a few of our World’s Healthiest seafoods are rich sources of vitamin E. Shrimp and sardines are two examples of this, with each topping 10% of daily requirements. Salmon and cod contain a little less vitamin E, yet can still be solid contributors.

Because most U.S. residents fail to get enough vitamin E in their daily diet, we recommend paying some attention to food sources of this important antioxidant. As long as you make a few of these vitamin E rich foods staple foods in your daily diet, you should be able to meet your intake requirements through foods alone..

Perhaps the easiest way to make sure you are getting enough vitamin E is by including sunflower seeds as snacks or as part of meals. This recipe for Healthy Turkey Salad contains nearly the whole Dietary Reference Intake (DRI) in one meal. Here are a few more recipes—Pureed Sweet Peas and 5-Minute Collard Greens with Sunflower Seeds—that include sunflower seeds.

We can also rely on meals that contain multiple foods providing more modest amounts of vitamin E, and allow them to stack up to become a more substantial amount. Our Poached Eggs Over Spinach and Mushrooms recipe contains spinach, eggs, and olive oil as sources of vitamin E. Together, they provide one-third of the RDA in only 10% of your daily calorie intake.

Recipes that contain nuts and nut butters will be a nice way to add vitamin E into your meals. You can be creative in the way you do this; for example, our 10-Minute Apricot Bars is a dessert recipe that provides more than 40% of the RDA for vitamin E.

There is a balance between getting plenty of fat-rich foods as sources of vitamin E and overdoing it and letting the calories pile up. As long as you choose wisely, you should be able to cover your vitamin E needs with just a few rich sources.

Nutrient Rating Chart

Introduction to Nutrient Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the World’s Healthiest Foods that are either an excellent, very good, or good source of vitamin E. Next to each food name, you’ll find the serving size we used to calculate the food’s nutrient composition, the calories contained in the serving, the amount of vitamin E contained in one serving size of the food, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration’s “Reference Values for Nutrition Labeling.” Read more background information and details of our rating system.

World’s Healthiest Foods ranked as quality sources of
vitamin E
Food Serving
Size
Cals Amount
(mg (ATE))
DRI/DV
(%)
Nutrient
Density
World’s
Healthiest
Foods Rating
Sunflower Seeds 0.25 cup 204.4 12.31 82 7.2 excellent
Spinach 1 cup 41.4 3.74 25 10.8 excellent
Swiss Chard 1 cup 35.0 3.31 22 11.3 excellent
Turnip Greens 1 cup 28.8 2.71 18 11.3 excellent
Asparagus 1 cup 39.6 2.70 18 8.2 excellent
Beet Greens 1 cup 38.9 2.61 17 8.1 excellent
Mustard Greens 1 cup 36.4 2.49 17 8.2 excellent
Chili Peppers 2 tsp 15.2 2.06 14 16.2 excellent
Almonds 0.25 cup 132.2 6.03 40 5.5 very good
Broccoli 1 cup 54.6 2.26 15 5.0 very good
Bell Peppers 1 cup 28.5 1.45 10 6.1 very good
Kale 1 cup 36.4 1.11 7 3.7 very good
Tomatoes 1 cup 32.4 0.97 6 3.6 very good
Avocado 1 cup 240.0 3.11 21 1.6 good
Peanuts 0.25 cup 206.9 3.04 20 1.8 good
Shrimp 4 oz 134.9 2.49 17 2.2 good
Olives 1 cup 154.6 2.22 15 1.7 good
Olive Oil 1 TBS 119.3 1.94 13 2.0 good
Collard Greens 1 cup 62.7 1.67 11 3.2 good
Cranberries 1 cup 46.0 1.20 8 3.1 good
Raspberries 1 cup 64.0 1.07 7 2.0 good
Kiwifruit 1 2 inches 42.1 1.01 7 2.9 good
Carrots 1 cup 50.0 0.81 5 1.9 good
Green Beans 1 cup 43.8 0.56 4 1.5 good
Leeks 1 cup 32.2 0.52 3 1.9 good
World’s Healthiest
Foods Rating
Rule
excellent DRI/DV>=75% OR
Density>=7.6 AND DRI/DV>=10%
very good DRI/DV>=50% OR
Density>=3.4 AND DRI/DV>=5%
good DRI/DV>=25% OR
Density>=1.5 AND DRI/DV>=2.5%

Impact of Cooking, Storage and Processing

The vitamin E in foods degrades slowly over time. For example, at room temperature, wheat flour loses about one-third of its vitamin E at close to one year of storage. That said, most people would be making use of their wheat flour long before this year-long time period.

Similarly, olive oil kept in a closed bottle will lose about 20-30% of its vitamin E over six months of storage. Don’t leave the bottle open, though, as all of the vitamin E will be gone after three or four months if you do. (While leaving olive oil in an opened bottle might sound unlikely, there are a good number of olive oil containers in the marketplace that feature an unsealed spout, and we do not recommend storage of olive oil in this way. You will find many more details about olive oil storage in our Extra Virgin Olive Oil food profile.)

Vitamin E also gets damaged by high heat cooking. For example, heating olive oil at 340°F (172°C) will lead to a destruction of the vitamin E, with almost half lost at three hours, and almost all of it gone by six hours. At WHFoods, we do not generally recommend any heating of extra virgin olive oil, and if we do include it in a heated sauce or other recipe, we heat it very gently and briefly. The delicate nature of vitamin E, and the fatty acids it protects, are good reasons to avoid heating of this oil. We adopt a similar approach for oil-rich foods like nuts and seeds, which we recommend be consumed in raw or minimally cooked form.

Usually in this section of our nutrient profiles, we discuss how specific nutrients are damaged in the storage of foods. But with respect to vitamin E, it is equally important to note that this nutrient can protect the foods from damage. For example, meat from chickens fed diets high in vitamin E show less evidence for free radical damage to their fats over 10 days of storage. Presumably, this vitamin E richness in the food consumed by the chickens helped protect their body fat from damage by oxygen. (We don’t have research comparing the human health consequences of consuming chicken fat with and without varying degrees of free radical damage. But we do know that animals fed diets that are rich in vitamin E typically provide us with animal foods that have good amounts of this vitamin as well.)

Risk of Dietary Deficiency

Given that the average U.S. adult eats exactly half the Dietary Reference Intake (DRI) for vitamin E—7.5 mg of the recommended 15 mg per day—the risk of dietary deficiency of vitamin E in the United States is substantial. In fact, vitamin E is one of the most common vitamin deficiencies in the United States, with as many as 92% of men and 98% of women failing to reach target intake goals.

In 2006, a research group from Tufts University did a statistical model of the best way to ensure vitamin E nutrition while staying within normal calorie levels and without impairing other nutrient intake. Among their conclusions, they asserted that a low intake of nuts and seeds—70% of their subjects didn’t eat any of either—was predictive of low vitamin E intake. Analyzing this conclusion in reverse, this is further evidence that nuts and seeds can be a good place to start when trying to achieve strong vitamin E nutrition. (Of course, low intake of dark green leafy vegetables by the average U.S. adult is another reason why so many people in the U.S. fail to meet their vitamin E needs.)

At first, it may seem like a paradox that we tend to eat diets high in fat, yet fail to have reliable vitamin E nutrition. That’s because not every type of dietary fat is as rich in vitamin E as nuts or seeds. The way plant cooking oils are manufactured and processed can lead to significant destruction of the nutrient before it ever gets to your plate. Generally speaking, you should expect highly processed foods (e.g., oils made from nuts and seeds) to contain less vitamin E than their whole, natural counterparts (e.g., whole nuts and seeds).

Other Circumstances that Might Contribute to Deficiency

Diets that overly restrict fat can limit vitamin E intake substantially. It will not be impossible to achieve vitamin E nutrition with a very low fat diet, but you’ll need to work much harder to do it. For example, if you decided that you wanted to get 100% of your DRI for vitamin E from sunflower seeds alone—our richest WHFoods source—you would need to allow for 18 grams of fat in your day’s food just to provide that amount. In an 1,800-calorie meal plan, that amount of fat would represent 9% of total calories all by itself. If you consumed an additional 18 grams of fat from all of the rest of your foods on that day, you diet for that day would already be close to 20% fat. On the other hand, if you were willing to obtain your vitamin E exclusively from dark green leafy vegetables, you could get 100% of the DRI from about 5 cups, representing 150-200 calories but only 2-5 grams of fat.

Any disease or medication that impairs the ability to digest fats will also endanger vitamin E nutrition. If this potentially describes you, make sure to talk to your doctor to make sure that you are protected against deficiency.

Relationship with Other Nutrients

Diets high in polyunsaturated fats—the type found in most fish and vegetable oils—may increase your requirement for vitamin E. Some sources recommend an older standard of an extra 0.6 mg of vitamin E for each gram of polyunsaturated fat. We are not convinced that this level of specificity is well supported, even though the principle of increasing vitamin E intake along with increased intake of polyunsaturated fat makes good sense to us. The World’s Healthiest Foods recipes tend to be moderate in polyunsaturated fats (and much higher in the more stable monounsaturated fats than most U.S. diets), and as such, we believe that our WHFoods recommendation of 15 milligrams of d-alpha-tocopherol equivalents per day should suffice for the average person.

Like other dietary antioxidants, vitamin E needs help from multiple nutrients to do its job at maximum efficiency. In particular, vitamin C helps to recycle vitamin E so it can continue to neutralize free radicals over and over again.

If vitamin K levels are low, too much vitamin E can lead to problems involving too easy bleeding from injuries and too slow closing of wounds. The amounts of vitamin E necessary to create this effect are large, however, and probably not achievable via diet alone. (In other words, dietary supplementation of vitamin E would most likely be required to create this degree of imbalance between vitamin E and vitamin K.)

Risk of Dietary Toxicity

We are not aware of a single published report of adverse effects from dietary vitamin E. Reflecting this lack of evidence for harm, the National Academy of Sciences set the Tolerable Upper Intake Limit (UL) for vitamin E at 1000 mg, more than 60 times the DRI, and more than 100 times what an average American eats in a day. You can feel confident that you are not eating toxic levels of vitamin E in your daily diet. Translated into IU, 1,000 milligrams of vitamin E represents 1,490 IU of d-alpha-tocopherol and 1,360 IU of d-alpha-tocopheryl acetate.

Disease Checklist

  • Cancer
  • Heart attack
  • Stroke
  • PMS
  • Fibrocystic breast disease
  • Diabetes
  • Epilepsy
  • Alzheimer’s disease
  • Parkinson’s disease
  • Macular degeneration
  • Cataract
  • Intermittent claudication
  • Cold sores
  • Immune health

Public Health Recommendations

In 2000, the National Academy of Sciences established a set of Dietary Reference Intakes (DRIs) for vitamin E. These recommendations included Adequate Intake (AI) levels for infants under one year of age, and Recommended Dietary Allowances (RDAs) for everyone else. These milligrams amounts represent alpha-tocopherol equivalents, or mg ATE. DRIs for vitamin E are as follows:

  • 0-6 months: 4 mg
  • 6-12 months: 5 mg
  • 1-3 years: 6 mg
  • 4-8 years: 7 mg
  • 9-13 years: 11 mg
  • 14+ years: 15 mg
  • Pregnant women: 15 mg
  • Lactating women: 19 mg

The most common DRI for vitamin E—15 milligrams ATE (alpha-tocopherol equivalents) —translates into approximately 22 IU of d-alpha-tocopherol and 20 IU of d-alpha-tocopheryl acetate. (The form of d-alpha-tocopherol is a naturally occurring form of vitamin E that is chemically classified as “non-esterified” and d-alpha-tocopheryl acetate is an esterified form commonly found in supplements due to its longer shelf life.)

The 2000 DRI recommendations also included a Tolerable Upper Intake Limit (UL) for adults of 1000 mg per day. As discussed above, this is more than an order of magnitude beyond even what the most vitamin E-rich diet could ever contain. For this reason, we should consider this UL more for supplement intake than guidance around dietary choices. Translated into IU, 1,000 milligrams of vitamin E represent 1,490 IU of d-alpha-tocopherol and 1,360 IU of d-alpha-tocopheryl acetate.

The Daily Value (DV) for vitamin E is 30 IU. The measurement of IU, short for International Units, is an older way to quantify vitamin E with 1 milligram of d-alpha-tocopherol from food equivalent to 1.49 IU.

References

  • Azzini E, Polito A, Fumagalli A, et al. Mediterranean diet effect: an Italian picture. Nutr J 2011;10:125.
  • Ben-Hassine K, Taamalli A, Ferchichi S, et al. Physicochemical and sensory characteristics of virgin olive oils in relation to cultivar, extraction system and storage conditions. Food Res Int 2013;54:1915-25.
  • Casal S, Malheiro R, Sendas A, et al. Olive oil stability under deep-frying conditions. Food Chem Toxicol 2010;48:2972-9.
  • Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press; 2000;284-324.
  • Gao X, Wilde PE, Lichtenstein AH, et al. The maximal amount of dietary alpha-tocopherol intake in US adults (NHANES 2001-2). J Nutr 2006;136:1021-6.
  • Krichene D, Allalout A, Mancebo-Campos V, et al. Stability of virgin olive oil and behavior of its natural antioxidants under medium temperature accelerated storage conditions. Food Chem 2010;121:171-7.
  • Luciano G, Moloney AP, Priolo A, et al. Vitamin E and polyunsaturated fatty acids in bovine muscle and the oxidative stability of beef from cattle receiving grass or concentrate-based rations. J Anim Sci 2011;89:3759-68.
  • Narciso-Gaytan C, Shin D, Sams AR, et al. Dietary lipid source and vitamin E effect on lipid oxidation stability of refrigerated fresh and cooked chicken meat. Poult Sci 2010;89:2726-34.
  • Nielsen MM, Hansen A. Stability of vitamin E in wheat flour and whole wheat flour during storage. Cereal Chem 2008;85:716-20.
  • Sen CK, Khanna S, and Roy S. (2006). Tocotrienols: vitamin E beyond tocopherols. Life Science 78(18): 2088-2098.
  • U.S. Department of Agriculture, Agricultural Research Service. 2012. Total Nutrient Intakes: Percent Reporting and Mean Amounts of Selected Vitamins and Minerals from Food and Dietary Supplements, by Family Income and Age, What We Eat in America, NHANES 2009-2010.
  • Valk EE, Hornstra G. Relationship between vitamin E requirement and polyunsaturated fatty acid intake in man: a review. Int J Vitam Nutr Res 2000;70:31-42.

Food Sources of Vitamin E

Dietitians

Information About Vitamin E

  • Vitamin E is a fat soluble vitamin that may improve immune function.
  • Vitamin E is an antioxidant that helps protects cells from damage by free radicals. Free radicals can damage tissues and organs in the body.
  • Vitamin E may play a role in preventing chronic disease such as heart disease and cancer but this is still being studied.
  • Research does not support taking vitamin E supplements for the prevention of chronic disease. Most Canadians can get the vitamin E they need from foods.

How Much Vitamin E Should I Aim For?

Age in Years Aim for an intake of
milligrams (mg) /day**
Stay below
mg/day*
Men and Women
19 and older
15* 1000*
Pregnant Women
19 and older
15* 1000*
Breastfeeding Women
19 and older
15* 1000*

*as alpha-tocopherol
**this amount includes sources of vitamin E from fortified food and supplements

Vitamin E Content of Some Common Foods

Vitamin E is found mainly in foods that contain fat like margarine, vegetable oil, wheat germ, nuts, nut butters, and seeds. The following table shows you foods which are sources of vitamin E.

Food                           Serving size Vitamin E (mg)
Vegetables and Fruits
Spinach, cooked 125 mL (½ cup) 2-4
Dandelion greens, raw 250 mL (1 cup) 2
Tomato sauce, canned 125 mL (½ cup) 2
Swiss chard, cooked 125 mL (½ cup) 2
Turnip greens, cooked 125 mL (½ cup) 2
Pepper, red, cooked 125 mL (½ cup) 2
Avocado ½ fruit 1-4
Grains Products
Cereal, wheat germ, toasted 30 g (¼ cup) 5
Milk and Alternatives This food group contains very little of this nutrient.
Meat and Alternatives
Egg, cooked 2 large 2-3
Fish and Seafood
Eel, cooked 75 g (2 ½ oz) 4
Halibut, cooked 75 g (2 ½ oz) 2
Herring, cooked 75 g (2 ½ oz) 2
Sardines, canned with oil 75 g (2 ½ oz) 2
Tuna, white, canned with oil 75 g (2 ½ oz) 2
Nuts and Seeds
Almonds, unblanched, without shell 60 mL (¼ cup) 9-10
Sunflower seeds, without shell 60 mL (¼ cup) 8-13
Almonds, blanched, without shell 60 mL (¼ cup) 2-9
Almond butter 30 mL (2 Tbsp) 8
Hazelnuts, without shell 60 mL (¼ cup) 5
Peanuts, without shell 60 mL (¼ cup) 3
Peanut butter 30 mL (2 Tbsp) 3
Pine nuts 60 mL (¼ cup) 3
Brazil nuts 60 mL (¼ cup) 2
Meat Alternatives
Meatless (fish sticks, wiener, chicken), cooked 75 g (2 ½ oz) 1-3
Meatless, luncheon slices 75 g (2 ½ oz) 2
Fats and Oils
Vegetable oil, wheat germ 5 mL (1 tsp) 7
Vegetable oil (sunflower, safflower) 5 mL (1 tsp) 2

Source: “Canadian Nutrient File 2010”
www.hc-sc.gc.ca/fn-an/nutrition/fiche-nutri-data/index-eng.php
[accessed March 23, 2012]

Antioxidants

Anti

Antioxidants are phytochemicals, vitamins and other nutrients that protect our cells from damage caused by free radicals. In vitro en in vivo studies have shown that antioxidants help prevent the free radical damage that is associated with cancer and heart disease. Antioxidants can be found in most fruits and vegetables but also culinary herbs and medicinal herbs can contain high levels of antioxidants. Dragland S and colleagues showed in their study entitled “Several Culinary and Medicinal Herbs are Important Sources of Dietary Antioxidants”, and published in the Journal of Nutrition (2003 May) that the antioxidant level of herbs can be as high as 465 mmol per 100 g.

A study in 2006 by Thompson HJ showed that a botanical diversity of fruits and vegetables plays a role in the biological effect of antioxidant phytochemicals. The consumption of smaller quantities of many phytochemicals may result in more health benefits than the consumption of larger quantities of fewer phytochemicals.

What are free radicals?

Free radicals are formed as part of our natural metabolism but also by environmental factors, including smoking, pesticides, pollution and radiation. Free radicals are unstable molecules which react easily with essential molecules of our body, including DNA, fat and proteins. All organic and inorganic materials consist of atoms, which can be bound together to form molecules. Each atom has a specific number of protons (positively charged) and electrons (negatively charged). Most single atoms are not stable because they have to few or to may electrons. Atoms try to reach a state of maximum stability by giving away or receiving electrons from other atoms, thereby forming molecules. Free radicals are molecules which have one electron too much or too less in order to be stable. Free radicals try to steal or give electrons to other molecules, thereby changing their chemical structure.

When a free radical attacks a molecule, it will then become a free radical itself, causing a chain reaction which can result in the destruction of a cell. Antioxidants have the property to neutralize free radicals without becoming a free radicals themselves. When antioxidants neutralize free radicals by receiving or donating an electron they do not become antioxidants themselves because they are stable in both forms. In other words, antioxidants are chemicals that offer up their own electrons to the free radicals, thus preventing cellular damage. However, when the antioxidant neutralizes a free radical it becomes inactive. Therefore we need to continuously supply our body with antioxidants. The action of free radicals could increase the risk of diseases such as cancer and hearth problems and could accelerate ageing. Antioxidants have the property to neutralize the free radicals and prevent damage. Well known examples of antioxidants are the vitamin C, E and beta-carotene. These three vitamins are often added to the so called ACE drinks. But there are numerous other rather unknown antioxidants such as lycopene, lutein,

Benefits of antioxidants

Numerous studies with plant phytochemicals show that phytochemicals with antioxidant activity may reduce risk of cancer and improve heart health.

Antioxidants reduce the risk of cancer

Not all results are conclusive but many studies show that antioxidants may reduce the risk of cancer. A large randomized trial on antioxidants and cancer risk was the Chinese Cancer Prevention Study (1993). This study showed that a combination of the antioxidants beta-carotene, vitamin E and selenium significantly reduced incidence of cancer. However, the Alpha-Tocopherol / Beta-Carotene Cancer Prevention Study (1994) showed that intake of beta-carotene increased lung cancer rates of male smokers.

Antioxidants protect the heart

Everyone knows that cholesterol causes heart diseases and tries to limit cholesterol intake. But a more important cause of fatty buildups in the arteries is the oxidation of low-density lipoprotein cholesterol. The use of dietary supplements of antioxidants could reduce the risk of cardiovascular disease, but there is no hard evidence. At this stage, studies only show that the intake of foods, naturally rich in antioxidants reduces this risk

List of phytochemicals

Alkaloids

Anthocyanins

Carotenoids

Coumestans

Flavan-3-Ols

Flavonoids

Hydroxycinnamic Acids

Isoflavones

Lignans

Monophenols

Monoterpenes

Organosulfides

Other Phytochemicals

Phenolic Acids

Phytosterols

Saponins

Stylbenes

Triterpenoids

Xanthophylls

http://www.phytochemicals.info/phytochemicals.php

List of plants containing phytochemicals

Vegetables

Fruits and Nuts

Medicinal Plants

Common Herbs

Beans and seeds

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Vitamin B12- You Need This

Vitamin B12

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Summary

  • Vitamin B12 or cobalamin plays essential roles in folate metabolism and in the synthesis of the citric acid cycle intermediate, succinyl-CoA. (More information)
  • Vitamin B12 deficiency is commonly associated with chronic stomachinflammation, which may contribute to an autoimmune vitamin B12malabsorption syndrome called pernicious anemia and to a food-bound vitamin B12 malabsorption syndrome. Impairment of vitamin B12 absorption can cause megaloblastic anemia and neurologic disorders in deficient subjects. (More information)
  • Normal function of the digestive system required for food-bound vitamin B12 absorption is commonly impaired in individuals over 60 years of age, placing them at risk for vitamin B12 deficiency. (More information)
  • Vitamin B12 and folate are important for homocysteine metabolism. Elevated homocysteine levels in blood are a risk factor for cardiovascular diseases (CVD). Although B vitamin supplementation has been proven effective to control homocysteine levels, current data from intervention trials have not shown that lowering homocysteine levels decreases CVD risk. (More information)
  • The preservation of DNA integrity is dependent on folate and vitamin B12availability. Poor vitamin B12 status has been linked to increased risk of breast cancer in some, but not all, observational studies. There is a need to evaluate whether supplemental vitamin B12, along with folic acid, could help reduce breast cancer incidence. (More information)
  • Low maternal vitamin B12 status has been associated with an increased risk of neural tube defects (NTD), but it is not known whether vitamin B12supplementation could help reduce the risk of NTD. (More information)
  • Vitamin B12 is essential for the preservation of the myelin sheath aroundneurons and for the synthesis of neurotransmitters. Whilehyperhomocysteinemia may increase the risk of cognitive impairment, it is not clear whether vitamin B12 deficiency contributes to the risk of dementiain the elderly. Although B-vitamin supplementation lowers homocysteine levels in older subjects, the long-term benefit is not yet known. (More information)
  • Both depression and osteoporosis have been linked to diminished vitamin B12 status and high homocysteine levels. (More information)
  • Products of animal origin constitute the primary source of vitamin B12. Older individuals and vegans are advised to use vitamin B12 fortified foods and supplements to meet their needs. (More information)
  • The long-term use of certain medications, such as inhibitors of stomach acid secretion, can adversely affect vitamin B12 absorption. (More information)

Vitamin B12 has the largest and most complex chemical structure of all thevitamins. It is unique among vitamins in that it contains a metal ion, cobalt. For this reason cobalamin is the term used to refer to compounds having vitamin B12activity. Methylcobalamin and 5-deoxyadenosylcobalamin are the forms of vitamin B12 used in the human body (1). The form of cobalamin used in most nutritional supplements and fortified foods, cyanocobalamin, is readily converted to 5-deoxyadenosylcobalamin and methylcobalamin in the body. In mammals, cobalamin is a cofactor for only two enzymes, methionine synthase and L-methylmalonyl-coenzyme A mutase (2).

Function

Cofactor for methionine synthase

Methylcobalamin is required for the function of the folate-dependent enzyme, methionine synthase. This enzyme is required for the synthesis of the amino acid,methionine, from homocysteine. Methionine in turn is required for the synthesis of S-adenosylmethionine, a methyl group donor used in many biological methylationreactions, including the methylation of a number of sites within DNA, RNA, andproteins (3). Aberrant methylation of DNA and proteins, which causes alterations inchromatin structure and gene expression, are a common feature of cancer cells. Inadequate function of methionine synthase can lead to an accumulation of homocysteine, which has been associated with increased risk of cardiovascular diseases (diagram).

Cofactor for L-methylmalonyl-coenzyme A mutase

5-Deoxyadenosylcobalamin is required by the enzyme that catalyzes the conversion of L-methylmalonyl-coenzyme A to succinyl-coenzyme A (succinyl-CoA), which then enters the citric acid cycle (see diagram). Succinyl-CoA plays an important role in the production of energy from lipids and proteins and is also required for thesynthesis of hemoglobin, the oxygen-carrying pigment in red blood cells (3).

Deficiency

In healthy adults, vitamin B12 deficiency is uncommon, mainly because total body stores can exceed 2,500 mcg, daily turnover is slow, and dietary intake of only 2.4 mcg/day is sufficient to maintain adequate vitamin B12 status (see RDA below) (4). In elderly individuals, vitamin B12 deficiency is more common mainly because of impaired intestinal absorption that can result in marginal to severe vitamin B12deficiency in this population.

Causes of vitamin B12 deficiency

Intestinal malabsorption, rather than inadequate dietary intake, can explain most cases of vitamin B12 deficiency (5). Absorption of vitamin B12 from food requires normal function of the stomach, pancreas, and small intestine. Stomach acid andenzymes free vitamin B12 from food, allowing it to bind to R-protein (also known as transcobalamin-1 or haptocorrin), found in saliva and gastric fluids. In the alkalineenvironment of the small intestine, R-proteins are degraded by pancreatic enzymes, freeing vitamin B12 to bind to intrinsic factor (IF), a protein secreted by specialized cells in the stomach. Receptors on the surface of the ileum (final part of the small intestine) take up the IF-B12 complex only in the presence of calcium, which is supplied by the pancreas (5). Vitamin B12 can also be absorbed by passive diffusion, but this process is very inefficient—only about 1% absorption of the vitamin B12dose is absorbed passively (2). The prevalent causes of vitamin B12 deficiency are (1) an autoimmune condition known as pernicious anemia, and (2) a disorder called food-bound vitamin B12 malabsorption. Both conditions have been associated with a chronic inflammatory disease of the stomach known as atrophic gastritis.

Atrophic gastritis

Atrophic gastritis is thought to affect 10%-30% of people over 60 years of age (6). The condition is frequently associated with the presence of autoantibodies directed towards stomach cells (see Pernicious anemia) and/or infection by the bacteria,Helicobacter pylori (H. pylori) (7). H. pylori infection induces chronic inflammation of the stomach, which may progress to peptic ulcer disease, atrophic gastritis, and/orgastric cancer in some individuals. Diminished gastric function in individuals with atrophic gastritis can result in bacterial overgrowth in the small intestine and cause food-bound vitamin B12 malabsorption. Vitamin B12 levels in serum, plasma, and gastric fluids are significantly decreased in individuals with H. pylori infection, and eradication of the bacteria has been shown to significantly improve vitamin B12serum concentrations (8).

Pernicious anemia

Pernicious anemia has been estimated to be present in approximately 2% of individuals over 60 years of age (9). Although anemia is often a symptom, the condition is actually the end stage of an autoimmune inflammation of the stomach known as autoimmune atrophic gastritis, resulting in destruction of stomach cells by one’s own antibodies (autoantibodies). Progressive destruction of the cells that line the stomach causes decreased secretion of acid and enzymes required to release food-bound vitamin B12. Antibodies to intrinsic factor (IF) bind to IF preventing formation of the IF-B12 complex, further inhibiting vitamin B12 absorption. About 20% of the relatives of pernicious anemia patients also have the condition, suggesting a genetic predisposition. It is also thought that H. pylori infection could be involved in initiating the autoimmune response in a subset of individuals (10). Further, co-occurrence of autoimmune atrophic gastritis with other autoimmune conditions, especially autoimmune thyroiditis and type 1 diabetes mellitus, has been reported (11, 12).

Treatment of pernicious anemia generally requires injections of vitamin B12 to bypass intestinal absorption. High-dose oral supplementation is another treatment option, because consuming 1,000 mcg (1 mg)/day of vitamin B12 orally should result in the absorption of about 10 mcg/day (1% of dose) by passive diffusion. In fact, high-dose oral therapy is considered to be as effective as intramuscular injection(4).

Food-bound vitamin B12 malabsorption

Food-bound vitamin B12 malabsorption is defined as an impaired ability to absorb food- or protein-bound vitamin B12; individuals with this condition can fully absorb the free form (13). While the condition is the major cause of poor vitamin B12 status in the elderly population, it is usually associated with atrophic gastritis, a chronicinflammation of the lining of the stomach that ultimately results in the loss of glands in the stomach (atrophy) and decreased stomach acid production (see Atrophic gastritis above). Because stomach acid is required for the release of vitamin B12from the proteins in food, vitamin B12 absorption is diminished. Decreased stomach acid production also provides an environment conducive to the overgrowth ofanaerobic bacteria in the stomach, which further interferes with vitamin B12absorption (3). Because vitamin B12 in supplements is not bound to protein, and because intrinsic factor (IF) is still available, the absorption of supplemental vitamin B12 is not reduced as it is in pernicious anemia. Thus, individuals with food-bound vitamin B12 malabsorption do not have an increased requirement for vitamin B12; they simply need it in the crystalline form found in fortified foods and dietary supplements.

Other causes of vitamin B12 deficiency

Other causes of vitamin B12 deficiency include surgical resection of the stomach or portions of the small intestine where receptors for the IF-B12 complex are located. Conditions affecting the small intestine, such as malabsorption syndromes (celiac disease and tropical sprue), may also result in vitamin B12 deficiency. Because thepancreas provides critical enzymes, as well as calcium required for vitamin B12absorption, pancreatic insufficiency may contribute to vitamin B12 deficiency. Since vitamin B12 is found only in foods of animal origin, a strict vegetarian (vegan) diet has resulted in cases of vitamin B12 deficiency. Moreover, alcoholics may experience reduced intestinal absorption of vitamin B12 (2), and individuals with acquired immunodeficiency syndrome (AIDS) appear to be at increased risk of deficiency, possibly related to a failure of the IF-B12 receptor to take up the IF-B12 complex(3). Further, long-term use of acid-reducing drugs has also been implicated in vitamin B12 deficiency (see Drug interactions).

Inherited disorders of vitamin B12 absorption

Rare cases of inborn errors of vitamin B12 metabolism have been reported in the literature (reviewed in 5). Imerslund-Gräsbeck syndrome is an inherited vitamin B12malabsorption syndrome that causes megaloblastic anemia and neurologic disorders of variable severity in affected subjects. Similar clinical symptoms are found in individuals with hereditary IF deficiency (also called congenital pernicious anemia) in whom the lack of IF results in the defective absorption of vitamin B12. Additionally,mutations affecting vitamin B12 transport in the body have been identified (14).

Symptoms of vitamin B12 deficiency

Vitamin B12 deficiency results in impairment of the activities of vitamin B12-requiring enzymes. Impaired activity of methionine synthase results in elevatedhomocysteine levels, while impaired activity of L-methylmalonyl-CoA mutase results in increased levels of a metabolite of methylmalonyl-CoA called methylmalonic acid (MMA). While individuals with mild vitamin B12 deficiency may not experience symptoms, blood levels of homocysteine and/or MMA may be elevated (15).

Megaloblastic anemia

Diminished activity of methionine synthase in vitamin B12 deficiency inhibits the regeneration of tetrahydrofolate (THF) and traps folate in a form that is not usable by the body (see diagram), resulting in symptoms of folate deficiency even in the presence of adequate folate levels. Thus, in both folate and vitamin B12 deficiencies, folate is unavailable to participate in DNA synthesis. This impairment of DNA synthesis affects the rapidly dividing cells of the bone marrow earlier than other cells, resulting in the production of large, immature, hemoglobin-poor red blood cells. The resulting anemia is known as megaloblastic anemia and is the symptom for which the disease, pernicious anemia, was named (3). Supplementation with folic acid will provide enough usable folate to restore normal red blood cell formation. However, if vitamin B12 deficiency is the cause, it will persist despite the resolution of the anemia. Thus, megaloblastic anemia should not be treated with folic acid until the underlying cause has been determined (16).

Neurologic symptoms

The neurologic symptoms of vitamin B12 deficiency include numbness and tingling of the hands and, more commonly, the feet; difficulty walking; memory loss; disorientation; and dementia with or without mood changes. Although the progression of neurologic complications is generally gradual, such symptoms may not be reversed with treatment of vitamin B12 deficiency, especially if they have been present for a long time. Neurologic complications are not always associated with megaloblastic anemia and are the only clinical symptom of vitamin B12deficiency in about 25% of cases (17). Although vitamin B12 deficiency is known to damage the myelin sheath covering cranial, spinal, and peripheral nerves, the biochemical processes leading to neurological damage in vitamin B12 deficiency are not yet fully understood (18).

Gastrointestinal symptoms

Tongue soreness, appetite loss, and constipation have also been associated with vitamin B12 deficiency. The origins of these symptoms are unclear, but they may be related to the stomach inflammation underlying some cases of vitamin B12deficiency and to the progressive destruction of the lining of the stomach (17).

The Recommended Dietary Allowance (RDA)

The RDA for vitamin B12 was revised by the Food and Nutrition Board (FNB) of the US Institute of Medicine in 1998. Because of the increased risk of food-bound vitamin B12 malabsorption in older adults, the FNB recommended that adults over 50 years of age get most of the RDA from fortified food or vitamin B12-containing supplements (17).

Recommended Dietary Allowance (RDA) for Vitamin B12
Life Stage  Age  Males (mcg/day)  Females (mcg/day) 
Infants 0-6 months 0.4 (AI) 0.4 (AI)
Infants 7-12 months 0.5 (AI) 0.5 (AI)
Children 1-3 years 0.9 0.9
Children 4-8 years 1.2 1.2
Children 9-13 years 1.8 1.8
Adolescents 14-18 years 2.4 2.4
Adults 19-50 years 2.4 2.4
Adults 51 years and older 2.4* 2.4*
Pregnancy all ages 2.6
Breast-feeding all ages 2.8

*Vitamin B12 intake should be from supplements or fortified foods due to the age-related increase in food-bound malabsorption.

Disease Prevention

Cardiovascular diseases

As mentioned above, chronic atrophic gastritis and infection by H. pylori can cause deficiency in vitamin B12 secondary to malabsorption disorders (see Causes of vitamin B12 deficiency). However, the occurrence of H. pylori infection and chronic atrophic gastritis did not modify the five-year incidence of cardiovascular accidents (stroke and heart attack) or mortality in a large cohort study of nearly 10,000 men and women over 50 years old (19). Yet, vitamin B12 status was not assessed in this study, despite the high prevalence of vitamin B12 deficiency in older individuals.

Homocysteine and cardiovascular diseases

Epidemiological studies indicate that even moderately elevated levels ofhomocysteine in the blood raise the risk of cardiovascular diseases (CVD) (20), though the mechanism by which homocysteine may increase the CVD risk remains the subject of a great deal of research (21). The amount of homocysteine in the blood is regulated by at least three vitamins: folate, vitamin B6, and vitamin B12(see diagram). An early analysis of the results of 12 randomized controlled trialsshowed that folic acid supplementation (0.5-5 mg/day) had the greatest lowering effect on blood homocysteine levels (25% decrease); co-supplementation with folic acid and vitamin B12 (500 mcg/day) provided an additional 7% reduction (32% decrease) in blood homocysteine concentrations (22). The results of a sequential supplementation trial in 53 men and women indicated that after folic acid supplementation, vitamin B12 became the major determinant of plasmahomocysteine levels (23). It is thought that the elevation of homocysteine levels might be partly due to vitamin B12 deficiency in individuals over 60 years of age. Two studies found blood methylmalonic acid (MMA) levels to be elevated in more than 60% of elderly individuals with elevated homocysteine levels. In the absence of impaired kidney function, an elevated MMA level in conjunction with elevated homocysteine suggests either a vitamin B12 deficiency or a combined vitamin B12and folate deficiency (24). Thus, it appears important to evaluate vitamin B12status, as well as kidney function, in older individuals with elevated homocysteine levels prior to initiating homocysteine-lowering therapy. For more information regarding homocysteine and CVD, see the article on folate.

Intervention studies

Although increased intake of folic acid and vitamin B12 is effective in decreasinghomocysteine levels, the combined intervention of these B vitamins did not lower risk for CVD. Indeed, several randomized, placebo-controlled trials have been conducted to determine whether homocysteine-lowering through folic acid, vitamin B12, and vitamin B6 supplementation reduces the incidence of CVD. A recent meta-analysis of data from 11 trials, including nearly 45,000 participants at risk of CVD, showed that B-vitamin supplementation had no significant effect on risk ofmyocardial infarction (heart attack) or stroke, nor did it modify the risk of all-cause mortality (25). Other meta-analyses that included patients with chronic kidney disease have confirmed the lack of effect of homocysteine-lowering on risk of myocardial infarction and death. However, stroke risk was significantly reduced by 7%-12% with the B-vitamin supplementation (26, 27). Another meta-analysis of 12clinical trials measuring flow-mediated vasodilation (FMD; a surrogate marker of vascular health) in response to homocysteine reduction revealed that B-vitamin supplementation was accompanied by an improved FMD in short-term <8 weeks) but not in long-term studies conducted in subjects with preexisting vascular diseases (28). Yet, some of the studies included in these meta-analyses did not use vitamin B12, and folate administration on its own has shown a protective role on vascular function and stroke risk (29). Besides, the high prevalence ofmalabsorption disorders and vitamin B12 deficiency in elderly individuals might warrant the use of higher doses of vitamin B12 than those used in these trials (30); in cases of malabsorption, only high-dose oral therapy or intramuscular injections can overcome vitamin B12 deficiency (4).

Cancer

Folate is required for synthesis of DNA, and there is evidence that decreased availability of folate results in strands of DNA that are more susceptible to damage. Deficiency of vitamin B12 traps folate in a form that is unusable by the body for DNA synthesis. Both vitamin B12 and folate deficiencies result in a diminished capacity formethylation reactions (see diagram). Thus, vitamin B12 deficiency may lead to an elevated rate of DNA damage and altered methylation of DNA, both of which are important risk factors for cancer. A series of studies in young adults and older men indicated that increased levels of homocysteine and decreased levels of vitamin B12in the blood were associated with a biomarker of chromosome breakage in white blood cells (reviewed in 31). In a double-blind, placebo-controlled study, the same biomarker of chromosome breakage was minimized in young adults who were supplemented with 700 mcg of folic acid and 7 mcg of vitamin B12 daily in cereal for two months (32).

Breast cancer

A case-control study compared prediagnostic levels of serum folate, vitamin B6, and vitamin B12 in 195 women later diagnosed with breast cancer and 195 age-matched, cancer-free women. Among postmenopausal women, the association between blood levels of vitamin B12 and breast cancer suggested a threshold effect. The risk of breast cancer was more than doubled in women with serum vitamin B12 levels in the lowest quintile compared to women in the four highest quintiles (33). However, the meta-analysis of this study with three additional case-control studies found no protection associated with high compared to low vitamin B12 serum levels (34). A case-control study in Mexican women (475 cases and 1,391 controls) reported that breast cancer risk for women in the highest quartile of vitamin B12 intake (7.3-7.7 mcg/day) was 68% lower than those in the lowest quartile (2.6 mcg/day). Stratification of the data revealed that the inverse association between dietary vitamin B12 intake and breast cancer risk was stronger in postmenopausal women compared to premenopausal women, though both associations were statistically significant. Moreover, among postmenopausal women, the apparent protection conferred by folate was only observed in women with the highest vitamin B12quartiles of intake (35). However, more recent case-control and prospective cohort studies have reported weak to no risk reduction with vitamin B12 intakes in different populations, including Hispanic, African American and European American women (36, 37). A meta-analysis of seven case-control and seven prospective cohort studies concluded that the risk of breast cancer was not modified by high versus low vitamin B12 intakes (34). There was no joint association between folate and vitamin B12 intakes and breast cancer risk. Presently, there is little evidence to suggest a relationship between vitamin B12 status and breast cancer. In addition, results from observational studies are not consistently in support of an association between high dietary folate intakes and reduced risk for breast cancer (see the article on Folate). There is a need to evaluate the effect of folate and vitamin B12supplementation in well-controlled, randomized, clinical trials, while considering various factors that modify breast cancer risk, such as menopausal status, ethnicity, and alcohol intake.

Neural tube defects

Neural tube defects (NTD) may result in anencephaly or spina bifida, which are mostly fatal congenital malformations of the central nervous system. The defects arise from failure of embryonic neural tube to close, which occurs between the 21stand 28th days after conception, a time when many women are unaware of their pregnancy (38). Randomized controlled trials have demonstrated 60% to 100% reductions in NTD cases when women consumed folic acid supplements in addition to a varied diet during the month before and the month after conception. Increasing evidence indicates that the homocysteine-lowering effect of folic acid plays a critical role in reducing the risk of NTD (39). Homocysteine may accumulate in the blood when there is inadequate folate and/or vitamin B12 for effective functioning of the methionine synthase enzyme. Decreased vitamin B12 levels and elevated homocysteine concentrations have been found in the blood and amniotic fluid of pregnant women at high risk of NTD (40). The recent meta-analysis of 12 case-control studies, including 567 mothers with current or prior NTD-affected pregnancy and 1,566 unaffected mothers, showed that low maternal vitamin B12 status was associated with an increased risk of NTD (41). Yet, whether vitamin B12supplementation may be beneficial in the prevention of NTD has not been evaluated(42).

Cognitive decline, dementia, and Alzheimer’s disease

The occurrence of vitamin B12 deficiency prevails in the elderly population and has been frequently associated with Alzheimer’s disease (reviewed in 43). One study found lower vitamin B12 levels in the cerebrospinal fluid of patients with Alzheimer’s disease than in patients with other types of dementia, though blood levels of vitamin B12 did not differ (44). The reason for the association of low vitamin B12status with Alzheimer’s disease is not clear. Vitamin B12 deficiency, like folatedeficiency, may lead to decreased synthesis of methionine and S-adenosylmethionine (SAM), thereby adversely affecting methylation reactions. Methylation reactions are essential for the metabolism of components of the myelinsheath of nerve cells as well as for synthesis of neurotransmitters (18). Other metabolic implications of vitamin B12 deficiency include the accumulation of homocysteine and methylmalonic acid, which might contribute to the neuropathologic features of dementia (43).

Observational studies

A large majority of cross-sectional and prospective cohort studies have associated elevated homocysteine concentrations with measures of poor cognitive scores and increased risk of dementia, including Alzheimer’s disease (reviewed in 45). A case-control study of 164 patients with dementia of Alzheimer’s type included 76 cases in which the diagnosis of Alzheimer’s disease was confirmed by examination of brain cells after death. Compared to 108 control subjects without evidence of dementia, subjects with dementia of Alzheimer’s type and confirmed Alzheimer’s disease had higher blood homocysteine levels and lower blood levels of folate and vitamin B12. Measures of general nutritional status indicated that the association of increased homocysteine levels and diminished vitamin B12 status with Alzheimer’s disease was not due to dementia-related malnutrition (46). In a sample of 1,092 men and women without dementia followed for an average of 10 years, those with higherplasma homocysteine levels at baseline had a significantly higher risk of developing Alzheimer’s disease and other types of dementia. Specifically, those with plasma homocysteine levels greater than 14 micromol/L had nearly double the risk of developing Alzheimer’s disease (47). A study in 650 elderly men and women reported that the risk of elevated plasma homocysteine levels was significantly higher in those with lower cognitive function scores (48). A prospective study in 816 elderly men and women reported that those with hyperhomocysteinemia(homocysteine levels >15 micromol/L) had a significantly higher risk of developing Alzheimer’s disease or dementia. Although raised homocysteine levels might be partly due to a poor vitamin B12 status, the latter was not related to risk of Alzheimer’s disease or dementia in this study (49).

A recent systematic review of 35 prospective cohort studies assessing the association between vitamin B12 status and cognitive deterioration in older individuals with or without dementia at baseline did not support a relationship between vitamin B12 serum concentrations and cognitive decline, dementia, or Alzheimer’s disease (50). Nevertheless, studies utilizing more sensitive biomarkersof vitamin B12 status, including measures of holo-transcobalamin (holo-TC; a vitamin B12 carrier) and methylmalonic acid, showed more consistent results and a trend toward associations between poor vitamin B12 status and faster cognitive decline and risk of Alzheimer’s disease (51-55). Besides, it cannot be excluded that the co-occurrence of potential confounders like elevated homocysteine level and poor folate status might mitigate the true contribution of vitamin B12 status to cognitive functioning (45).

Intervention studies

High-dose B-vitamin supplementation has been proven effective for treatinghyperhomocysteinemia in elderly individuals with or without cognitive impairment. However, homocysteine-lowering trials have produced equivocal results regarding the prevention of cognitive deterioration in this population. A systematic review andmeta-analysis of 18 randomized, placebo-controlled trials examining the effect of B-vitamin supplementation did not find that the decrease in homocysteine level prevented or delayed cognitive decline among older subjects (56). A more recent randomized, double-blind, placebo-controlled clinical trial in 900 older individuals at high risk of cognitive impairment found that daily supplementation of 400 mcg of folic acid and 100 mcg of vitamin B12 for two years significantly improved measures of immediate and delayed memory and slowed the rise in plasma homocysteine concentrations (57). However, supplemented subjects had no reduction in homocysteine concentrations compared to baseline, nor did they perform better in processing speed tests compared to placebo. Another two-year, randomized, placebo-controlled study in elderly adults reported that a daily regimen of 800 mcg of folic acid, 500 mcg of vitamin B12, and 20 mg of vitamin B6 significantly reduced the rate of brain atrophy compared to placebo treatment (0.5% vs. 3.7%). Interestingly, a greater benefit was seen in those with high compared to low homocysteine concentrations at baseline, suggesting the importance of lowering homocysteine levels in prevention of brain atrophy and cognitive decline (58, 59). The authors attributed the changes in homocysteine levels primarily to vitamin B12(59). Finally, the most recent randomized, double blind, placebo-controlled trial in over 2,500 individuals who suffered a stroke showed that the normalization of homocysteine concentrations by B-vitamin supplementation (2 mg of folic acid, 500 mcg of vitamin B12, and 25 mg of vitamin B6) did not improve cognitive performance or decrease incidence of cognitive decline compared to placebo (60). Currently, there is a need for larger trials to evaluate the effect of B-vitamin supplementation on long-term outcomes, such as the incidence of Alzheimer’s disease.

Depression

Observational studies have found as many as 30% of patients hospitalized for depression are deficient in vitamin B12 (61). A cross-sectional study of 700 community-living, physically disabled women over the age of 65 found that vitamin B12-deficient women were twice as likely to be severely depressed as non-deficient women (62). A population-based study in 3,884 elderly men and women with depressive disorders found that those with vitamin B12 deficiency were almost 70% more likely to experience depression than those with normal vitamin B12 status(63). The reasons for the relationship between vitamin B12 deficiency and depression are not clear but may involve a shortage in S-adenosylmethionine (SAM). SAM is a methyl group donor for numerous methylation reactions in the brain, including those involved in the metabolism of neurotransmitters whose deficiency has been related to depression (64). Severe vitamin B12 deficiency in a mouse model showed dramatic alterations in the level of DNA methylation in the brain, which might lead to neurologic impairments (65). This hypothesis is supported by several studies that have shown supplementation with SAM improves depressive symptoms (66-69).

Increased homocysteine level is another nonspecific biomarker of vitamin B12deficiency that has been linked to depressive symptoms in the elderly (70). However, in a recent cross-sectional study conducted in 1,677 older individuals, higher vitamin B12 plasma levels, but not changes in homocysteine concentrations, were correlated with a lower prevalence of depressive symptoms (71). Few studies have examined the relationship of vitamin B12 status, homocysteine levels, and the development of depression over time. In a randomized, placebo-controlled,intervention study with over 900 older participants experiencing psychological distress, daily supplementation with folic acid (400 mcg) and vitamin B12 (100 mcg) for two years did not reduce the occurrence of symptoms of depression despite significantly improving blood folate, vitamin B12, and homocysteine levels compared to placebo (72). However, in a long-term randomized, double-blind, placebo-controlled study among sufferers of cerebrovascular accidents at high risk of depression, daily supplementation with 2 mg of folic acid, 25 mg of vitamin B6, and 500 mcg vitamin B12 significantly lowered the risk of major depressive episodes during a seven-year follow-up period compared to placebo (73). Although it cannot yet be determined whether vitamin B12 deficiency plays a causal role in depression, it may be beneficial to screen for vitamin B12 deficiency in older individuals as part of a medical evaluation for depression.

Osteoporosis

High homocysteine levels may affect bone remodeling by increasing bone resorption(breakdown), decreasing bone formation, and reducing bone blood flow. Another proposed mechanism involves the binding of homocysteine to the collagenous matrix of bone, which may modify collagen properties and reduce bone strength (reviewed in 74). Alterations of bone biomechanical properties can contribute toosteoporosis and increase the risk of fractures in the elderly. Since vitamin B12 is a determinant of homocysteine metabolism, it was suggested that the risk of osteoporotic fractures in older subjects might be enhanced by vitamin B12deficiency. A meta-analysis of four observational studies, following a total of 7,475 older individuals for 3 to 16 years, found a weak association between an elevation in vitamin B12 of 50 picomoles/L in blood and a reduction in fracture risk (75). Arandomized, placebo-controlled trial in 559 elderly individuals with low serum levels of folate and vitamin B12 and at increased risk of fracture evaluated the combined supplementation of very high doses of folic acid (5 mg/day) and vitamin B12 (1.5 mg/day). The two-year study found that the supplementation improved B-vitamin status, decreased homocysteine concentrations, and reduced risk of total fractures compared to placebo (76). However, a multicenter study in 5,485 subjects withcardiovascular disease or diabetes mellitus showed that daily supplementation with folic acid (2.5 mg), vitamin B12 (1 mg), and vitamin B6 (50 mg) lowered homocysteine concentrations but had no effect on fracture risk compared to placebo(77). Another small, randomized, double-blind trial in 93 individuals with low vitamin D status found no additional benefit of B-vitamin supplementation (50 mg/day of vitamin B6, 0.5 mg/day of folic acid, and 0.5 mg/day of vitamin B12) on markers of bone health over a one-year period beyond that associated with vitamin D and calcium supplementation. Yet, the short-scale of the study did not permit a conclusion on whether the lowering of homocysteine through B-vitamin supplementation could have long-term benefits on bone strength and fracture risk(78). A large intervention study conducted in older people with no preexisting conditions is under way to evaluate the effect of B-vitamin supplementation on markers of bone health and incidence of fracture; this trial might clarify whether B vitamins could have a protective effect on bone health in the elderly population(79).

Sources

Food sources

Only bacteria can synthesize vitamin B12 (80). Vitamin B12 is present in animal products, such as meat, poultry, fish (including shellfish), and to a lesser extent dairy products and eggs (1). Fresh pasteurized milk contains 0.9 mcg per cup and is an important source of vitamin B12 for some vegetarians (17). Those strict vegetarians who eat no animal products (vegans) need supplemental vitamin B12 to meet their requirements. Recent analyses revealed that some plant-source foods, such as certain fermented beans and vegetables and edible algae and mushrooms, contain substantial amounts of bioactive vitamin B12 (81). Together with B-vitaminfortified food and supplements, these foods may constitute new alternatives to prevent vitamin B12 deficiency in individuals consuming vegetarian diets. Also, individuals over the age of 50 should obtain their vitamin B12 in supplements or fortified foods (e.g., fortified cereals) because of the increased likelihood of food-bound vitamin B12 malabsorption with increasing age.

Most people do not have a problem obtaining the RDA of 2.4 mcg/day of vitamin B12in food. According to a US national survey, the average dietary intake of vitamin B12 is 5.4 mcg/day for adult men and 3.4 mcg/day for adult women. Adults over the age of 60 had an average dietary intake of 4.8 mcg/day (42). However, consumption of any type of vegetarian diet dramatically increases the prevalence of vitamin B12 deficiency in individuals across all age groups (82). Some foods with substantial amounts of vitamin B12 are listed in the table below along with their vitamin B12 content in micrograms (mcg). For more information on the nutrient content of specific foods, search the USDA food composition database.

Food Serving Vitamin B12 (mcg)
Clams (steamed) 3 ounces 84.1
Mussels (steamed) 3 ounces 20.4
Mackerel (Atlantic, cooked, dry-heat) 3 ounces* 16.1
Crab (Alaska king, steamed) 3 ounces 9.8
Beef (lean, plate steak, cooked, grilled) 3 ounces 6.9
Salmon (chinook, cooked, dry-heat) 3 ounces 2.4
Rockfish (cooked, dry-heat) 3 ounces 1.0
Milk (skim) 8 ounces 0.9
Turkey (cooked, roasted) 3 ounces 0.8
Brie (cheese) 1 ounce 0.5
Egg (poached) 1 large 0.4
Chicken (light meat, cooked, roasted) 3 ounces 0.3

*A three-ounce serving of meat or fish is about the size of a deck of cards.

Supplements

Cyanocobalamin is the principal form of vitamin B12 used in oral supplements, but methylcobalamin is also available as a supplement. Cyanocobalamin is available by prescription in an injectable form and as a nasal gel for the treatment of pernicious anemia. Over-the-counter preparations containing cyanocobalamin include multivitamins, vitamin B-complex supplements, and single-nutrient, vitamin B12supplements (83).

Safety

Toxicity

No toxic or adverse effects have been associated with large intakes of vitamin B12from food or supplements in healthy people. Doses as high as 2 mg (2,000 mcg) daily by mouth or 1 mg monthly by intramuscular (IM) injection have been used to treat pernicious anemia without significant side effects (84). When high doses of vitamin B12 are given orally, only a small percentage can be absorbed, which may explain the low toxicity (4). Because of the low toxicity of vitamin B12, no tolerable upper intake level (UL) has been set by the US Food and Nutrition Board (17).

Drug interactions

A number of drugs reduce the absorption of vitamin B12. Proton-pump inhibitors (e.g., omeprazole and lansoprazole), used for therapy of Zollinger-Ellison syndromeand gastroesophageal reflux disease (GERD), markedly decrease stomach acid secretion required for the release of vitamin B12 from food but not fromsupplements. Long-term use of proton-pump inhibitors has been found to decrease blood vitamin B12 levels. However, vitamin B12 deficiency does not generally develop until after at least three years of continuous therapy (85, 86). Another class of gastric acid inhibitors known as Histamine2 (H2)-receptor antagonists (e.g., cimetidine, famotidine, and ranitidine), often used to treat peptic ulcer disease, has also been found to decrease the absorption of vitamin B12 from food. It is not clear whether the long-term use of H2-receptor antagonists could cause overt vitamin B12 deficiency (87, 88). Individuals taking drugs that inhibit gastric acid secretion should consider taking vitamin B12 in the form of a supplement because gastric acid is not required for its absorption. Other drugs found to inhibit vitamin B12 absorption from food include cholestyramine (a bile acid-binding resin used in the treatment of high cholesterol), chloramphenicol and neomycin (antibiotics), and colchicine (medicine for gout treatment). Metformin, a medication for individuals with type 2diabetes, was found to decrease vitamin B12 absorption by tying up free calcium required for absorption of the IF-B12 complex (89). However, the clinical significance of this is unclear (90). It is not known whether calcium supplementation can reverse vitamin B12 malabsorption; therefore, calcium supplementation is not currently prescribed for the prevention or treatment of metformin-induced vitamin B12deficiency (91). Previous reports that megadoses of vitamin C destroy vitamin B12have not been supported (92) and may have been an artifact of the assay used to measure vitamin B12 levels (17).

Nitrous oxide, a commonly used anesthetic, oxidizes and inactivates vitamin B12, thus inhibiting both of the vitamin B12-dependent enzymes, and can produce many of the clinical features of vitamin B12 deficiency, such as megaloblastic anemia orneuropathy. Since nitrous oxide is commonly used for surgery in the elderly, some experts feel vitamin B12 deficiency should be ruled out prior to its use (6, 15).

Large doses of folic acid given to an individual with an undiagnosed vitamin B12deficiency could correct megaloblastic anemia without correcting the underlying vitamin B12 deficiency, leaving the individual at risk of developing irreversibleneurologic damage (17). For this reason, the Food and Nutrition Board of the US Institute of Medicine advises that all adults limit their intake of folic acid (supplements and fortification) to 1,000 mcg (1 mg) daily.

Linus Pauling Institute Recommendation

A varied diet should provide enough vitamin B12 to prevent deficiency in most individuals 50 years of age and younger. Strict vegetarians and women planning to become pregnant should take a multivitamin supplement daily or eat fortifiedcereal, which would ensure a daily intake of 6 to 30 mcg of vitamin B12 in a form that is easily absorbed. Higher doses of vitamin B12 supplements are recommended for patients taking medications that interfere with its absorption (see Drug interactions).

Older adults (> 50 years)

Because vitamin B12 malabsorption and vitamin B12 deficiency are more common in older adults, the Linus Pauling Institute recommends that adults older than 50 years take 100 to 400 mcg/day of supplemental vitamin B12.

http://lpi.oregonstate.edu/infocenter/vitamins/vitaminB12/#food_source

References


Written in March 2003 by:
Jane Higdon, Ph.D.
Linus Pauling Institute
Oregon State University

Updated in January 2014 by:
Barbara Delage, Ph.D.
Linus Pauling Institute
Oregon State University

Reviewed in April 2014 by:
Joshua W. Miller, Ph.D.
Professor and Chair, Department of Nutritional Sciences
Rutgers, The State University of New Jersey

Copyright 2000-2014  Linus Pauling Institute


Disclaimer

The Linus Pauling Institute Micronutrient Information Center provides scientific information on the health aspects of dietary factors and supplements, foods, and beverages for the general public. The information is made available with the understanding that the author and publisher are not providing medical, psychological, or nutritional counseling services on this site. The information should not be used in place of a consultation with a competent health care or nutrition professional.

The information on dietary factors and supplements, foods, and beverages contained on this Web site does not cover all possible uses, actions, precautions, side effects, and interactions. It is not intended as nutritional or medical advice for individual problems. Liability for individual actions or omissions based upon the contents of this site is expressly disclaimed.

Plant Nutrients

Sixteen chemical elements are known to be important to a plant’s growth and survival. The sixteen chemical elements are divided into two main groups: non-mineral and mineral.
Non-Mineral Nutrients
The Non-Mineral Nutrients are hydrogen (H), oxygen (O), & carbon (C).

These nutrients are found in the air and water.In a process calledphotosynthesis, plants use energy from the sun to change carbon dioxide (CO2 – carbon and oxygen) and water (H2O- hydrogen and oxygen) into starches and sugars. These starches and sugars are the plant’s food.

Photosynthesismeans “making things with light”.

Since plants get carbon, hydrogen, and oxygen from the air and water, there is little farmers and gardeners can do to control  how much of these nutrients a plant can use.
Mineral Nutrients
The 13 mineral nutrients, which come from the soil, are dissolved in water and absorbed through a plant’s roots. There are not always enough of these nutrients in the soil for a plant to grow healthy. This is why many farmers and gardeners use fertilizers to add the nutrients to the soil.The mineral nutrients are divided into two groups:
macronutrients and micronutrients.

Macronutrients 

Macronutrients can be broken into two more groups:
primary and secondary nutrients.The primary nutrients are nitrogen (N), phosphorus (P), andpotassium (K). These major nutrients usually are lacking from the soil first because plants use large amounts for their growth and survival.

The secondary nutrients are calcium (Ca), magnesium (Mg), andsulfur (S). There are usually enough of these nutrients in the soil so fertilization is not always needed. Also, large amounts of Calcium and Magnesium are added when lime is applied to acidic soils. Sulfur is usually found in sufficient amounts from the slow decomposition of soil organic matter, an important reason for not throwing out grass clippings and leaves.

Micronutrients

Micronutrients are those elements essential for plant growth which are needed in only very small (micro) quantities . These elements are sometimes called minor elements or trace elements, but use of the term micronutrient is encouraged by the American Society of Agronomy and the Soil Science Society of America. The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl),manganese (Mn), molybdenum (Mo) and zinc (Zn). Recycling organic matter such as grass clippings and tree leaves is an excellent way of providing micronutrients (as well as macronutrients) to growing plants.


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Soil
In general, most plants grow by absorbing nutrients from the soil. Their ability to do this depends on the nature of the soil. Depending on its location, a soil contains some combination of sand, silt, clay, and organic matter. The makeup of a soil (soil texture) and its acidity (pH) determine the extent to which nutrients are available to plants. wheelbarrow
Soil Texture

(the amount of sand, silt, clay, and organic matter in the soil) 
 
Soil texture affects how well nutrients and water are retained in the soil. Clays and organic soils hold nutrients and water much better than sandy soils. As water drains from sandy soils, it often carries nutrients along with it. This condition is called leaching. When nutrients leach into the soil, they are not available for plants to use. 

An ideal soil contains equivalent portions of sand, silt, clay, and organic matter. Soils across North Carolina vary in their texture and nutrient content, which makes some soils more productive than others. Sometimes, the nutrients that plants need occur naturally in the soil. Othertimes, they must be added to the soil as lime or fertilizer.

 

Soil pH (a measure of the acidity or alkalinity of the soil)

      Soil pH is one of the most important soil properties that affects the availability of nutrients.
      • Macronutrients tend to be less available in soils with low pH.
      • Micronutrients tend to be less available in soils with high pH.

Lime

      can be added to the soil to make it less sour (acid) and also supplies calcium and magnesium for plants to use. Lime also raises the pH to the desired range of 6.0 to 6.5.

In this pH range, nutrients are more readily available to plants, and microbial populations in the soil increase. Microbes convert nitrogen and sulfur to forms that plants can use. Lime also enhances the physical properties of the soil that promote water and air movement.

It is a good idea to have your

soil tested

. If you do, you will get a report that explains how much lime and fertilizer your crop needs. 

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Macronutrients
Nitrogen (N)
  • Nitrogen is a part of all living cells and is a necessary part of all proteins, enzymes and metabolic processes involved in the synthesis and transfer of energy.
  • Nitrogen is a part of chlorophyll, the green pigment of the plant that is responsible for photosynthesis.
  • Helps plants with rapid growth, increasing seed and fruit production and improving the quality of leaf and forage crops.
  • Nitrogen often comes from fertilizer application and from the air (legumes get their N from the atmosphere, water or rainfall contributes very little nitrogen)
Phosphorus (P)
  • Like nitrogen, phosphorus (P) is an essential part of the process of photosynthesis.
  • Involved in the formation of all oils, sugars, starches, etc.
  • Helps with the transformation of solar energy into chemical energy; proper plant maturation; withstanding stress.
  • Effects rapid growth.
  • Encourages blooming and root growth.
  • Phosphorus often comes from fertilizer, bone meal, and superphosphate.
Potassium (K)
  • Potassium is absorbed by plants in larger amounts than any other mineral element except nitrogen and, in some cases, calcium.
  • Helps in the building of protein, photosynthesis, fruit quality and reduction of diseases.
  • Potassium is supplied to plants by soil minerals, organic materials, and fertilizer.
Calcium (Ca)
  • Calcium, an essential part of plant cell wall structure, provides for normal transport and retention of other elements as well as strength in the plant. It is also thought to counteract the effect of alkali salts and organic acids within a plant.
  • Sources of calcium are dolomitic lime, gypsum, and superphosphate.
Magnesium (Mg)
  • Magnesium is part of the chlorophyll in all green plants and essential for photosynthesis. It also helps activate many plant enzymes needed for growth.
  • Soil minerals, organic material, fertilizers, and dolomitic limestone are sources of magnesium for plants.
Sulfur (S)
  • Essential plant food for production of protein.
  • Promotes activity and development of enzymes and vitamins.
  • Helps in chlorophyll formation.
  • Improves root growth and seed production.
  • Helps with vigorous plant growth and resistance to cold.
  • Sulfur may be supplied to the soil from rainwater. It is also added in some fertilizers as an impurity, especially the lower grade fertilizers. The use of gypsum also increases soil sulfur levels.

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Micronutrients
Boron (B)
  • Helps in the use of nutrients and regulates other nutrients.
  • Aids production of sugar and carbohydrates.
  • Essential for seed and fruit development.
  • Sources of boron are organic matter and borax
Copper (Cu)
  • Important for reproductive growth.
  • Aids in root metabolism and helps in the utilization of proteins.
Chloride (Cl)
  • Aids plant metabolism.
  • Chloride is found in the soil.
Iron (Fe) 
  • Essential for formation of chlorophyll.
  • Sources of iron are the soil, iron sulfate, iron chelate.
Manganese (Mn) 
  • Functions with enzyme systems involved in breakdown of carbohydrates, and nitrogen metabolism.
  • Soil is a source of manganese.
Molybdenum (Mo)
  • Helps in the use of nitrogen
  • Soil is a source of molybdenum.
Zinc (Zn)
  • Essential for the transformation of carbohydrates.
  • Regulates consumption of sugars.
  • Part of the enzyme systems which regulate plant growth.
  • Sources of zinc are soil, zinc oxide, zinc sulfate, zinc chelate.

Plant Nutrients

Sixteen chemical elements are known to be important to a plant’s growth and survival. The sixteen chemical elements are divided into two main groups: non-mineral and mineral.
Non-Mineral Nutrients
The Non-Mineral Nutrients are hydrogen (H), oxygen (O), & carbon (C).

These nutrients are found in the air and water.In a process calledphotosynthesis, plants use energy from the sun to change carbon dioxide (CO2 – carbon and oxygen) and water (H2O- hydrogen and oxygen) into starches and sugars. These starches and sugars are the plant’s food.

Photosynthesismeans “making things with light”.

Since plants get carbon, hydrogen, and oxygen from the air and water, there is little farmers and gardeners can do to control  how much of these nutrients a plant can use.
Mineral Nutrients
The 13 mineral nutrients, which come from the soil, are dissolved in water and absorbed through a plant’s roots. There are not always enough of these nutrients in the soil for a plant to grow healthy. This is why many farmers and gardeners use fertilizers to add the nutrients to the soil.The mineral nutrients are divided into two groups:
macronutrients and micronutrients.

Macronutrients 

Macronutrients can be broken into two more groups:
primary and secondary nutrients.The primary nutrients are nitrogen (N), phosphorus (P), andpotassium (K). These major nutrients usually are lacking from the soil first because plants use large amounts for their growth and survival.

The secondary nutrients are calcium (Ca), magnesium (Mg), andsulfur (S). There are usually enough of these nutrients in the soil so fertilization is not always needed. Also, large amounts of Calcium and Magnesium are added when lime is applied to acidic soils. Sulfur is usually found in sufficient amounts from the slow decomposition of soil organic matter, an important reason for not throwing out grass clippings and leaves.

Micronutrients

Micronutrients are those elements essential for plant growth which are needed in only very small (micro) quantities . These elements are sometimes called minor elements or trace elements, but use of the term micronutrient is encouraged by the American Society of Agronomy and the Soil Science Society of America. The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl),manganese (Mn), molybdenum (Mo) and zinc (Zn). Recycling organic matter such as grass clippings and tree leaves is an excellent way of providing micronutrients (as well as macronutrients) to growing plants.


Go to top of the page

Soil
In general, most plants grow by absorbing nutrients from the soil. Their ability to do this depends on the nature of the soil. Depending on its location, a soil contains some combination of sand, silt, clay, and organic matter. The makeup of a soil (soil texture) and its acidity (pH) determine the extent to which nutrients are available to plants. wheelbarrow
Soil Texture

(the amount of sand, silt, clay, and organic matter in the soil) 
 
Soil texture affects how well nutrients and water are retained in the soil. Clays and organic soils hold nutrients and water much better than sandy soils. As water drains from sandy soils, it often carries nutrients along with it. This condition is called leaching. When nutrients leach into the soil, they are not available for plants to use. 

An ideal soil contains equivalent portions of sand, silt, clay, and organic matter. Soils across North Carolina vary in their texture and nutrient content, which makes some soils more productive than others. Sometimes, the nutrients that plants need occur naturally in the soil. Othertimes, they must be added to the soil as lime or fertilizer.

 

Soil pH (a measure of the acidity or alkalinity of the soil)

      Soil pH is one of the most important soil properties that affects the availability of nutrients.
      • Macronutrients tend to be less available in soils with low pH.
      • Micronutrients tend to be less available in soils with high pH.

Lime

      can be added to the soil to make it less sour (acid) and also supplies calcium and magnesium for plants to use. Lime also raises the pH to the desired range of 6.0 to 6.5.

In this pH range, nutrients are more readily available to plants, and microbial populations in the soil increase. Microbes convert nitrogen and sulfur to forms that plants can use. Lime also enhances the physical properties of the soil that promote water and air movement.

It is a good idea to have your

soil tested

. If you do, you will get a report that explains how much lime and fertilizer your crop needs. 

Go to the top of the page

Macronutrients
Nitrogen (N)
  • Nitrogen is a part of all living cells and is a necessary part of all proteins, enzymes and metabolic processes involved in the synthesis and transfer of energy.
  • Nitrogen is a part of chlorophyll, the green pigment of the plant that is responsible for photosynthesis.
  • Helps plants with rapid growth, increasing seed and fruit production and improving the quality of leaf and forage crops.
  • Nitrogen often comes from fertilizer application and from the air (legumes get their N from the atmosphere, water or rainfall contributes very little nitrogen)
Phosphorus (P)
  • Like nitrogen, phosphorus (P) is an essential part of the process of photosynthesis.
  • Involved in the formation of all oils, sugars, starches, etc.
  • Helps with the transformation of solar energy into chemical energy; proper plant maturation; withstanding stress.
  • Effects rapid growth.
  • Encourages blooming and root growth.
  • Phosphorus often comes from fertilizer, bone meal, and superphosphate.
Potassium (K)
  • Potassium is absorbed by plants in larger amounts than any other mineral element except nitrogen and, in some cases, calcium.
  • Helps in the building of protein, photosynthesis, fruit quality and reduction of diseases.
  • Potassium is supplied to plants by soil minerals, organic materials, and fertilizer.
Calcium (Ca)
  • Calcium, an essential part of plant cell wall structure, provides for normal transport and retention of other elements as well as strength in the plant. It is also thought to counteract the effect of alkali salts and organic acids within a plant.
  • Sources of calcium are dolomitic lime, gypsum, and superphosphate.
Magnesium (Mg)
  • Magnesium is part of the chlorophyll in all green plants and essential for photosynthesis. It also helps activate many plant enzymes needed for growth.
  • Soil minerals, organic material, fertilizers, and dolomitic limestone are sources of magnesium for plants.
Sulfur (S)
  • Essential plant food for production of protein.
  • Promotes activity and development of enzymes and vitamins.
  • Helps in chlorophyll formation.
  • Improves root growth and seed production.
  • Helps with vigorous plant growth and resistance to cold.
  • Sulfur may be supplied to the soil from rainwater. It is also added in some fertilizers as an impurity, especially the lower grade fertilizers. The use of gypsum also increases soil sulfur levels.

Go to the top of the page

Micronutrients
Boron (B)
  • Helps in the use of nutrients and regulates other nutrients.
  • Aids production of sugar and carbohydrates.
  • Essential for seed and fruit development.
  • Sources of boron are organic matter and borax
Copper (Cu)
  • Important for reproductive growth.
  • Aids in root metabolism and helps in the utilization of proteins.
Chloride (Cl)
  • Aids plant metabolism.
  • Chloride is found in the soil.
Iron (Fe) 
  • Essential for formation of chlorophyll.
  • Sources of iron are the soil, iron sulfate, iron chelate.
Manganese (Mn) 
  • Functions with enzyme systems involved in breakdown of carbohydrates, and nitrogen metabolism.
  • Soil is a source of manganese.
Molybdenum (Mo)
  • Helps in the use of nitrogen
  • Soil is a source of molybdenum.
Zinc (Zn)
  • Essential for the transformation of carbohydrates.
  • Regulates consumption of sugars.
  • Part of the enzyme systems which regulate plant growth.
  • Sources of zinc are soil, zinc oxide, zinc sulfate, zinc chelate.

http://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htm