Vegetarian Diet

The term “vegetarian” is used to describe any diet that emphasizes the consumption of plant foods and discourages the consumption of animal foods. In its most restrictive form, a vegetarian diet excludes all animal foods, including animal flesh, dairy products and eggs. Vegan, macrobiotic, and fruitarian diets fall into this category. Less restrictive forms include the lacto-ovo vegetarian diet (includes dairy products and eggs) and the lacto-vegetarian diet (includes dairy products). The popularity of vegetarianism is on the rise in the United States, and converts cite personal health, spiritual and religious beliefs, concern about animal welfare, and distress about the economic and environmental consequences of a meat-based diet as reasons for adopting a plant-based diet. This movement towards vegetarianism is consistent with a growing body of research that touts the health benefits of plant-based diets including lower rates of obesity, hypertension, diabetes, arthritis, colon cancer, prostate cancer, and heart disease. When carefully planned and well-balanced, vegetarian diets provide sufficent amounts of all essential nutrients. However, because infants, children, adolescents, and pregnant and lactating women have increased caloric and nutrient needs, care must be taken to include a variety of foods from all food groups (fruits, vegetables, legumes, nuts, seeds, and, for those vegetarians who consume them, eggs and/or dairy products) to ensure that nutritional needs are met.

Throughout human history, advocates of vegetarianism have employed moral and spiritual arguments to express their disdain for eating the flesh of animals. Ancient writers such as Ovid and Plutarch deplored the killing of innocent creatures for food. Plutarch stated: “I am astonished to think what appetite first induced man to taste of a dead carcass or what motive could suggest the notion of nourishing himself with the flesh of animals which he saw, just before, bleating, bellowing, walking, and looking about them.” The Greek philosopher Pythagoras, who lived towards the end of the 6th century BC, argued that the flesh of beasts contaminated and brutalized the soul. In recognition of Pythagoras’ commitment, vegetarians were known as Pythagoreans until the mid-19th century. Other writers have associated vegetarianism with spiritual enlightenment. According to the 17th century English vegetarian Thomas Tryon, “…by thoroughly cleansing the outward court of terrestrial nature, it opens the windows of the inward senses of the soul.” (Whorton, 1994) For these reasons, a variety of religions, including Brahminism, Buddhism, Hinduism and the Seventh Day Adventists encourage followers to abstain from eating meat.

While philosophers have long articulated the moral and spiritual benefits of the vegetarian way of life, the pursuit of vegetarianism for the reasons of health did not begin until the 19th Century. Early in the 1800s, scientific and medical evidence for the benefits of plant-based diets began to emerge. In 1806, a London physician named William Lambe cured himself of longstanding illness by abstaining from meat. Encouraged by his experience, Lambe began to treat his patients with the same diet prescription. His work eventually convinced many of his colleagues that a plant-based diet was as, or more healthy than a meat-based diet. Around the same time in the United States, a popular health reform movement was gathering steam. This movement was initiated by Presbyterian minister Sylvester Graham, most well-known now as the father of the Graham cracker. Graham, who preached on temperance and denounced the growing use of refined flour, was also a vegetarian. Following the establishment of the British Vegetarian Society in 1847, Graham worked to organize a similar group in America, and the American Vegetarian Society was founded in 1850. In the late 1800s, John Harvey Kellog, a Seventh Day Adventist and the maker of cereals bearing his family name, labored to make Americans aware of the nutritional benefits of vegetarianism.

During the 19th and 20th centuries, scientists continued to evaluate the health benefits of vegetarian diets. But, even as a growing body of scientific evidence emerged to validate this way of life, vegetarianism remained, to a large extent, on the fringe of society. Even as late as the 1970s, vegetarianism was associated with the counter-culture, a diet adhered to only by flower children and religious fanatics.

During the last few decades of the 20th Century, the popularity of vegetarianism surged in the United States and Europe, as evidenced by the number of people claiming to be vegetarian and the increase in published literature promoting the health benefits of vegetarian diets. According to one source, in 1994 more than 12 million people in the United States reported themselves to be vegetarians, compared to 6 million in 1986 (Rajaram and Sabate, 2000). The Vegetarian Resource Group, a leading source of information on vegetarianism, reported the results of a 2000 survey that estimated the number of vegetarians in the United States to be only about 5 million people. In Europe, it is estimated that 5% of the populations of both the United Kingdom and Germany are vegetarian, and 4% of the adult population of the Netherlands follows a vegetarian diet (Hebbelinck, 1999). Vegetarians cite personal health, spiritual and religious beliefs, concern about animal welfare, and distress over the economic and environmental consequences of a meat-based diet as reasons for adopting a plant-based diet.

Are you a vegetarian? If so, you are in good company! Famous vegetarians include Mahatma Ghandi, Carl Lewis (Olympic athlete), Natalie Merchant (musician); Vanessa Williams (actress and singer); Raffi (children’s musician); Dean Ornish, MD (cardiologist and author); Paul McCartney (rock musician); Desmond Howard (Heisman trophy winner); Dustin Hoffman (actor); Tony LaRussa (pro-baseball manager); and Fred Rogers (TV’s Mr. Rogers).

In general, the term “vegetarian” is used to describe any diet that emphasizes the consumption of plant foods, avoids the consumption of animal flesh, and discourages the consumption of other animal products. In its most restrictive form, a vegetarian diet excludes all animal foods, including animal flesh, dairy products and eggs. Vegan, macrobiotic, and fruitarian diets fall into this category. Less restrictive forms include the lacto-ovo vegatarian diet (includes dairy products and eggs) and the lacto-vegetarian diet (includes dairy products). Interestingly, many people who claim to be “vegetarian” do not fit into any of the categories above. Many who consider themselves vegetarian eat fish on occasion, while other self-defined vegetarians include poultry and/or pork in their diet.

To be considered healthy, a vegetarian diet should include daily consumption of a variety of foods from all the plant groups, such as grains, legumes, vegetables, fruit, nuts, seeds, plant oils, herbs and spices. To maximize the nutritional value of their diet, vegetarians should choose whole, organic, minimally processed foods, and go easy on highly processed foods, junk foods and sweets. A vegetarian diet featuring lots of chips, cookies and frozen confections, even if made from organic ingredients, will not promote health.

A significant body of population-based research documents the health benefits of a vegetarian diet. For example, a paper published in 1999 summarized the results of a study associating diet with chronic disease in a group of nearly 35,000 Seventh day Adventists living in California. The members of the group who followed a vegetarian diet (defined as eating no red meat, poultry, or fish)had lower incidences of many diseases, including obesity, hypertension, diabetes, arthritis, colon cancer, prostate cancer, and ischemic heart disease than the nonvegetarians (Fraser, 1999). Also in 1999, Key, et al., analyzed the combined results from five studies involving a total of more than 76,000 people that compared the incidence of disease among vegetarians (defined as eating no red meat, poultry or fish) to that of nonvegetarians with similar lifestyles. Mortality from ischemic heart disease was 24% lower in vegetarians than nonvegetarians (Key, et al).

For many years, the health benefits of vegetarian diets were thought to be due to the absence of meat and other animal fats in the diet, and the subsequent reduction in the intake of several known dietary villains such as total fat, saturated fat and cholesterol. In support of this explanation, scientists pointed to results of research studies that link high intake of the above-mentioned dietary villains to an increased risk for various medical conditions including heart disease and cancer. Researchers have also suggested that the health benefits of vegetarian diets are due, at least in part, to other healthy lifestyle choices that often accompany vegatarianism, such as increased physical activity and not smoking.

Clearly, avoiding meat and animal fats and increasing physical activity contribute to the health benefits of a vegetarian lifestyle. However, recent research has focused on the presence of a variety of specific nutrients in plant foods that have health-promoting qualities.

Fiber: Plant foods such as whole grains, beans, legumes, fruits, vegetables, and nuts provide dietary fiber. High intake of dietary fiber may reduce your risk of developing heart disease, diabetes, premenstrual syndrome, and colon cancer.
Antioxidants: Fruits and vegetables contain high amounts of vitamin C, vitamin E, and carotenoids, all of which act as antioxidants, protecting your cells from the damaging effects of free radicals
Phytonutrients: Plant foods contain a variety of unique nutrients such as phytoestrogens, indoles, isothiocyanates, and flavonoids. Emerging research indicates that these nutrients may help prevent cancer, heart disease, and other degenerative diseases.
Advocates of vegetarianism also point to research on the environmental impact of meat-based diets to support their lifestyle. Consider these facts:

Thirty-eight percent of total grain production worldwide is fed to chicken, pigs, and cattle. Seventy percent of grain production in the United States is fed to livestock. (Gussow, 1994)
The United States is losing approximately 4 million acres of cropland each year due to soil erosion. It is estimated that 85% of this topsoil loss is directly related to raising livestock. (The Vegetarian Times Complete Cookbook, 1995)
More than 4,000 gallons of water are needed to produce a single day’s worth of food for the typical meat eater. In comparison, an ovo-lacto vegetarian requires only 1,200 gallons of water, and a vegan needs a mere 300 gallons. (The Vegetarian Times Complete Cookbook, 1995)
One pound of pork that provides between 1000 and 2000 calories takes 14,000 calories of energy to produce in the United States. (Gussow, 1994)
Huge livestock farms generate an estimated five tons of animal manure for every person in the United States. In one day, a single hog farm produces the same amount of raw waste as a city of 12,000 people. In one year, a large egg farm yields enough manure to fill 1,400 dump trucks. Manure from livestock farms pollutes rivers and lakes, resulting in overgrowth of algae and pathogenic (disease-causing) microorganisms.
In Latin America, 20 million hectares of tropical forest have been converted to cattle pasture since 1970. This deforestation has had a devastating impact on plant and animal diversity in Latin America. (Gussow, 1994)
Many medical authorities link the emergence of foodborne pathogens such as E.coli and Mad Cow disease with factory farming methods.
One-third of the irrigation water in the State of California is used to produce feed for dairy cattle.
Foods Emphasized
Vegetarian diets emphasize the consumption of grains, vegetables, fruits, beans, soy products, nuts, and seeds.

Foods Avoided
All true vegetarian diets exclude meat, fish, and poultry. Strict vegetarian diets also exclude dairy products and eggs, while more liberal vegetarian diets include dairy products and eggs.

Nutrient Excesses/Deficiencies
Historically, vegetarian diets have been condemned by nutritionists for providing inadequate amounts of several important nutrients that are found primarily in animal foods including iron, protein, calcium, vitamin D, and vitamin B12. However, it is now widely accepted by most nutritionists that vegetarian diets, when a variety of plant foods are included, can meet or exceed the nutritional requirements of most individuals.

Although vegetarian diets do tend to be lower in iron than meat-based diets, vegetarians do not have a higher rate of iron deficiency anemia than meat eaters. This may be explained by the fact that the iron found in vegetarian diets (in vegetables and unrefined grains) is often accompanied, in the food or in the meal, by large amounts of vitamin C, which increases the absorption of the mineral.

Vegetarians also tend to eat less protein than meat-eaters, but their intake still exceeds the required amounts. Several decades ago, it was believed that vegetarians had to eat complementary proteins at each meal to ensure adequate intake of all the essential amino acids. It is now known that vegetarians need not worry about complementary proteins at each meal, as long as they ensure intake of foods containing all essential amino acids during the day. For more information on complementary proteins, see the article on protein in our nutrient database.

Since vitamin D-fortified milk is the primary food source of vitamin D in the United States, vegetarians who exclude dairy products from their diet may require a supplemental source, especially if they do not have consistent exposure to the sun.

As is the case with vitamin D, the calcium intake of vegetarians depends to a great extent on whether or not dairy products are included in the diet. All vegetarians should incorporate plant foods (dark green leafy vegetables and organic tofu) that contain calcium, but this is especially important for those who exclude dairy products. Interestingly, because vegetarian diets tend to be lower in protein, vegetarians may retain more calcium than meat-eaters, thus promoting bone health.

Vegans must pay attention to their intake of vitamin B12 since this vitamin occurs primarily in animal foods, and its deficiency can cause a variety of irreversible neurological problems. A study published in 1999 involving 245 Australian Seventh-day Adventist ministers evaluated the vitamin B12 status of lactovo-vegetarianns and vegans who were not taking vitamin B12 supplements. Seventy three percent of the participants had low serum vitamin B12 concentrations. (Hokin, 1999) Interestingly, vitamin B12 cannot be made by animals or plants, but only by microorganisms, like bacteria. When plant foods are fermented with the use of B12-producing bacteria, they end up containing B12. Otherwise, they usually don’t. Sea plants are an exception to the fermented plant rule since they can contain small amounts of B12 from contact with microorganisms in the ocean. Although animals cannot make vitamin B12, they are able to store B12 in their liver and muscles. The storage of B12 by animals explains why animal foods are the primary food sources of dietary B12.

Another nutrient to which vegetarians should pay special attention is docosahexaenoic acid (DHA). DHA is an omega 3 fatty acids believed to play an important role in the development and function of the central nervous system, as well as the eyes. It occurs naturally in meat, fish, eggs, and milk. DHA an also be synthesized by the body from alpha-linolenic acid, an omega 3 essential fatty acid, although it is not yet clear to what extent this conversion actually takes place. This process is slowed by the presence of large amounts of another essential fatty acid called linoleic acid, which is an omega 6 fat found in corn, safflower and sunflower oils. Vegetarians, and especially vegans, may want to supplement with DHA. To maintain a beneficial ratio of omega 3 fatty acids to omega 6 fatty acids, they may also want to and/or substitute foods containing alpha-linolenic acid, such as flaxseeds, pumpkin seeds and soybeans for foods containing linoleic acid.

Who Benefits
A vegetarian diet may be especially beneficial for overweight individuals, as well as for women with premenstrual syndrome and individuals with diabetes, high blood pressure and/or cardiovascular disease.

Who is Harmed
Because infants, children, adolescents, and pregnant and lactating women have increased caloric and nutrient needs, individuals in any of these groups choosing to follow a vegetarian diet must take care to include a variety and adequate amount of food from all food groups (fruits, vegetables, grains, legumes, nuts, and seeds) to ensure that nutritional needs are met.

Menu Ideas
These vegetarian recipes were developed by the George Mateljan Foundation.

For additional information about vegetarianism, contact the following organizations:

The North American Vegetarian Society
P.O. Box 72
Dolgeville, NY 13329
Phone: 518-568-7970
Vegetarian Resource Center
P.O. Box 38-1068
Cambridge, MA 02238
Phone: 617-625-3790
The Vegetarian Resource Group
P.O. Box 1463
Baltimore, MD 21203
Phone: 410-366-8343
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Editors of Vegetarian Times. Vegetarian Times Complete Cookbook. Macmillan: New York, 1995. 1995.
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Weaver CM, Plawecki KL. Dietary calcium: adequacy of a vegetarian diet. Am J Clin Nutr 1994; 59(suppl): 1238S-41S. 1994.
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Willett WC. Convergence of philosophy and science: the Third International Congress on Vegetarian Nutrition. Am J Clin Nutr 1999; 79(suppl): 434S-8S. 1999.


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