Milk and lactose intakes and ovarian cancer

Milk and lactose intakes and ovarian cancer risk in the Swedish Mammography Cohort1,2,3

  1. Susanna C Larsson,
  2. Leif Bergkvist, and
  3. Alicja Wolk

+Author Affiliations


  1. 1From the Division of Nutritional Epidemiology, The National Institute of Environmental Medicine, Karolinska Institutet, Stockholm (SCL and AW), and the Department of Surgery and the Center for Clinical Research, Uppsala University, Central Hospital, Västerås, Sweden (LB)

Abstract

Background: High intakes of dairy products and of the milk sugar lactose have been hypothesized to increase ovarian cancer risk, but prospective data are scarce.

Objective: We examined the association between intakes of dairy products and lactose and the risk of total epithelial ovarian cancer and its subtypes.

Design: This was a prospective population-based cohort study of 61 084 women aged 38–76 y who were enrolled in the Swedish Mammography Cohort. Diet was assessed in 1987–1990 with the use of a self-administered food-frequency questionnaire. During an average follow-up of 13.5 y, 266 women were diagnosed with invasive epithelial ovarian cancer; 125 of those women had serous ovarian cancer.

Results: After adjustment for potential confounders, women who consumed ≥4 servings of total dairy products/d had a risk of serous ovarian cancer (rate ratio: 2.0; 95% CI: 1.1, 3.7; P for trend = 0.06) twice that of women who consumed <2 servings/d. No significant association was found for other subtypes of ovarian cancer. Milk was the dairy product with the strongest positive association with serous ovarian cancer (rate ratio comparing consuming ≥2 glasses milk/d with consuming milk never or seldom: 2.0; 95% CI: 1.1, 3.7; P for trend = 0.04). We observed a positive association between lactose intake and serous ovarian cancer risk (P for trend = 0.006).

Conclusions: Our data indicate that high intakes of lactose and dairy products, particularly milk, are associated with an increased risk of serous ovarian cancer but not of other subtypes of ovarian cancer. Future studies should consider ovarian cancer subtypes separately.

Colon Cancer Prevention

Colon Cancer Prevention: Is it the Fiber or the Phytates?

on May 21st, 2015


Dietary factors are considered the most important environmental risk factors for cancer. Within recent years, a large number of naturally occurring health-enhancing substances of plant origin known as phytonutrients have been recognized to have beneficial effects on certain cancers. Beans, chickpeas, split peas and lentils are packed with all sorts of wonderful nutrients, but the reason they may protect against several degenerative diseases may be due to non-nutritive compounds, or even so-called “antinutrient” compounds like phytates.

Phytates have a somewhat negative reputation for binding to certain minerals (like iron, zinc and manganese) and slowing their absorption. But they have also been found to offer anti-inflammatory health benefits. “The reputation of phytate has had a roller coaster ride ever since its discovery; it has undergone alternate eminence and infamy.” (I previously explored the surprising new science about phytates in my video Phytates for the Prevention of Osteoporosis). Could they play a potential role in preventing colon cancer?

In the U.S., colon cancer is the second leading cause of cancer death, but some parts of the world have had just a tiny fraction of our rates, with the highest rates reported in Connecticut, and the lowest in Kampala, Uganda. The famous surgeon Denis Burkitt spent 24 years in Uganda and most of the hospitals he contacted there had never seen a case of colon cancer. Noting they live off diets centered on whole plant foods, he figured that maybe it was the fiber that was so protective.

Some studies have called that interpretation into question. Danes appear to have more colon cancer than Finns, yet Danes consume almost twice the dietary fiber. What else, then, could explain the low cancer rates among plant-based populations? Well, fiber isn’t the only thing found in whole plant foods, but missing from processed and animal foods. Maybe it’s the phytate.

Dietary phytate, rather than fiber per se, may be the most important variable governing the frequency of colon cancer, as phytate is known to be a powerful inhibitor of the iron-mediated production of hydroxyl radicals, a particularly dangerous type of free radical. So the standard American diet may be a double whammy, the heme iron in muscle meat plus the lack of phytate in refined plant foods to extinguish the iron radicals.

This may account for what researchers found in the Adventist study, highlighted in my video, Phytates for the Prevention of Cancer. They found excess risk of cancer for higher intakes of both red meat and white meat, suggesting all meats contribute to colon cancer formation — about twice the risk for red meat eaters, and three times the risk for those eating chicken and fish.

Those who eat meat could reduce their risk in two ways: by cutting down on meat or by eating more beans, an excellent source of phytates.

So it’s not just how much meat we eat, but our meat to vegetables ratio. Between the two extremes (high-vegetable and low-meat diets versus high-meat and low-vegetable diets) a risk ratio of about eight appears to exist, sufficient to explain a substantial part of the international variation in the incidence of colorectal cancer. Those with the worst of both worlds, high meat and low vegetable, were at eight times the risk.

More on colon cancer in Stool Size Matters.

Here are a few of my latest videos on the latest wonders of the musical fruit:

What about that music, though? See my blog Beans and Gas: Clearing the air.

What about soybeans and cancer? See Breast Cancer Survival and Soy and BRCA Breast Cancer Genes and Soy.

Other ways to mediate the effects of meat intake can be found in my video Reducing Cancer Risk in Meateaters.

For more about how phytates may play a role in both cancer prevention and treatment see Phytates for Rehabilitating Cancer Cells and Phytates for the Treatment of Cancer.

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

Image Credit: Ton Rulkens / Flickr

Why the Egg-Cancer Link?

News

Why the Egg-Cancer Link?

August 21, 2014 by Michael Greger M.D. in News with 0 Comments

Why the Egg Cancer-link?

Two million men in the U.S. are living with prostate cancer — but that’s better than dying from prostate cancer. Catch it when it’s localized and the five-year survival is practically guaranteed, but once it really starts spreading, chances drop to one in three. “Thus, identification of modifiable factors that affect the progression of prostate cancer is something that deserves study,” noted Dr. Erin Richard and colleagues at Harvard. So, they took more than a thousand men with early stage prostate cancer and followed them for a couple years to see if there was anything in their diet associated with a resurgence of the cancer, such as spreading to the bone.

Compared to men who hardly ate any eggs, men who ate even less than a single egg a day had a significant 2-fold increased risk of prostate cancer progression. The only thing worse was poultry consumption, with up to four times the risk of progression among high-risk men. They think it might be the cooked meat carcinogens that for some reason build up more in chicken and turkey muscle than in other meats. For more on these so-called heterocyclic amines, see my videos: Heterocyclic Amines in Eggs, Cheese, and Creatine?, Estrogenic Cooked Meat Carcinogens, and PhIP: The Three Strikes Breast Carcinogen.

But what about the eggs? Why would less than once-a-day egg consumption double the risk of cancer progression? “A plausible mechanism that may explain the association between eggs and prostate cancer progression is high dietary choline,” the researchers suggested.  Egg consumption is a determinant of how much choline you have in your blood, and higher blood choline has been associated with a greater risk of getting prostate cancer in the first place. So the choline in eggs may both increase one’s risk of getting it and having it spread.

Studies have associated choline consumption not just with getting cancer and spreading cancer, but also with significantly increased risk of dying from it. Those who ate the most had a 70% increased risk of lethal prostate cancer. Another recent study found that men who consumed two and a half or more eggs per week — that’s just like one egg every three days — had an 81 percent increased risk of lethal prostate cancer.

Maybe that’s why meat, milk, and eggs have all been associated with advanced prostate cancer—because of the choline. Choline is so concentrated in cancer cells that doctors can follow choline uptake to track the spread of cancer throughout the body. But why may dietary choline increase the risk of lethal prostate cancer? Dietary choline is converted in the gut to trimethylamine (see my video Carnitine, Choline, Cancer and Cholesterol: The TMAO Connection), so the Harvard researchers speculated that the TMAO from the high dietary choline intake may increase inflammation, which may promote progression of prostate cancer to a lethal disease.

In one of my videos, Eggs and Choline: Something Fishy, I talked about what trimethylamine might do to one’s body odor.

In the New England Journal of Medicine, the same Cleveland Clinic research team that did the famous study on carnitine repeated the study, but instead of feeding people a steak, they fed people some hard-boiled eggs. Just as they suspected, a similar spike in that toxic TMAO. So it’s not just red meat. And the link between TMAO levels in the blood and strokes, heart attacks, and death was seen even in low-risk groups like those with low-risk cholesterol levels. Thus, because of the choline, eating eggs may increase our risk regardless of what our cholesterol is.

It’s ironic that the choline content of eggs is something the egg industry actually boasts about. And the industry is aware of the cancer data. Through the Freedom of Information Act, I was able to get my hands on an email (which you can view in my video, Eggs, Choline, and Cancer) from the executive director of the industry’s Egg Nutrition Center to an American Egg Board executive talking about how choline may be a culprit in promoting cancer progression. “Certainly worth keeping in mind,” he said, “as we continue to promote choline as another good reason to consume eggs.”

 

With regard to the prevention of prostate cancer progression, chicken and eggs may be the worst foods to eat, but what might be the best? See my video Prostate Cancer Survival: The A/V Ratio.

To prevent prostate cancer in the first place, see videos such as:

What about reversing cancer progression? See Dr. Ornish’s work Cancer Reversal Through Diet?, followed up by the Pritikin Foundation: Ex Vivo Cancer Proliferation Bioassay. Flax may help as well (Flaxseed vs. Prostate Cancer).

-Michael Greger, M.D.

Researchers Unveil Six Dietary Guidelines for Cancer Prevention

WASHINGTON—Six dietary guidelines – more aggressive than previous cancer prevention advice will be unveiled in the June 30 issue of theJournal of the American College of Nutrition.

The cancer prevention guidelines, emphasizing a diet rich in plant-based foods, such as soy beans and cruciferous, allium, and carotenoid vegetables, are based on the principle that diet changes are justified, even when evidence on certain issues are up for debate. The recommendations urge the same kind of precautionary approach health experts took against tobacco decades earlier, before smoking bans were enforced, and warn about the association between cancer and alcohol, red and processed meats, dairy products, and carcinogens in well-cooked meats, including beef, poultry, and fish.

“The key recommendation is to build meals around fruits, vegetables, and legumes,” says study author Neal Barnard, M.D., president of the nonprofit Physicians Committee and an adjunct associate professor of medicine at the George Washington University School of Medicine and Health Sciences. “Plant-based foods provide an antioxidant boost and help promote a healthy weight, reducing the risk for all types of cancer in the long run.”

The six dietary recommendations to reduce risk of several types of cancer are:

1. Limit or avoid dairy products to reduce the risk of prostate cancer.

Findings: Consuming thirty-five grams of dairy protein each day, the equivalent of one large cup of cottage cheese, increases risk of prostate cancer by 32 percent. Drinking two glasses of milk each day increases risk of prostate cancer by 60 percent.

Note: Calcium supplements appear to have the same effect as milk intake. Men who supplement with more than 400 milligrams of calcium per day increase risk for fatal prostate cancer by 51 percent.

2. Limit or avoid alcohol to reduce the risk of cancers of the mouth, pharynx, larynx, esophagus, colon, rectum, and breast.

Findings: One drink per week increases risk of mouth, pharynx, and larynx cancers by 24 percent. Two to three drinks per day increase risk of colorectal cancer by 21 percent.

Note: The alcohol itself (rather than additives) appears to be the cause of cancer, and all types of alcoholic beverages (wine, beer, and spirits) are problematic.

3. Avoid red and processed meats to reduce the risk of cancers of the colon and rectum.

Findings: Each 50-gram daily serving of processed meat, equivalent to two slices of bacon or one sausage link, increases risk of colorectal cancer by 21 percent. Each 120-gram daily serving of red meat, equivalent to a small steak, increases risk of colorectal cancer by 28 percent.

Note: The heme iron, nitrites, heterocyclic amines, and overabundance of essential amino acids in red and processed meats are all believed to contribute to cancerous cell growth in the body.

4. Avoid grilled, fried, and broiled meats to reduce the risk of cancers of the colon, rectum, breast, prostate, kidney, and pancreas.

Findings: Four types of heterocyclic amines (HCAs) are associated with cancer of the colon and rectum. HCAs form from creatine and amino acids in cooked skeletal muscle, increasing with higher cooking times and higher temperatures. When ingested, HCAs can disrupt DNA synthesis.

Note: In addition to the cancers listed above, HCAs are also associated, to a weaker extent, with cancers of the breast, prostate, kidney, and pancreas.

5. Consume soy products to reduce risk of breast cancer and to reduce the risk of recurrence and mortality for women previously treated for breast cancer

Findings: Evidence from Asian and Western countries shows that soy products are associated with reduced cancer risk. Chinese women who consume more than 11.3 grams of soy protein, equivalent to half a cup of cooked soybeans, each day during adolescence have a 43 percent reduced risk of premenopausal breast cancer, compared with women who consume 1.7 grams.

Research in Shanghai shows that women with breast cancer who consume 11 grams of soy protein each day can reduce mortality and risk of recurrence by about 30 percent.  U.S. populations show similar findings: the higher the isoflavone intake from soy products, the less risk of mortality and recurrence in women with breast cancer.

Note: When choosing soy products, opt for natural forms, such as edamame, tempeh, or organic tofu, as opposed to soy protein concentrates and isolates, common in powders and pills.

6. Emphasize fruits and vegetables to reduce risk of several common forms of cancer.

Findings: Fruits and vegetables, especially leafy greens, help reduce overall cancer risk. A high intake of cruciferous vegetables, such as broccoli, kale, and cabbage, is associated with an 18 percent reduced risk of colorectal cancer and reduced risk of lung and stomach cancers.

Women who consume the most carotenoid-rich vegetables, such as carrots and sweet potatoes, lower their risk of breast cancer by 19 percent. Overall, women who consume the highest quantities of any kind of fruit or vegetable reduce breast cancer risk by 11 percent.  A high intake of tomato products has been shown to reduce risk of gastric cancer by 27 percent. Garlic and other allium vegetables, such as onions, significantly reduce risk for gastric cancer, while a Western diet (high amounts of meat and fat with minimal amounts of fruits and vegetables) doubles the risk.

Note: Some components in soybeans, green tea, turmeric, grapes, tomatoes, and other plant foods have the ability to regulate apoptosis (a natural process for destroying unhealthy cells), an important pathway for cancer prevention.

six dietary guidelines for cancer prevention
Dietary Guidelines for Cancer Prevention (PDF)

“There’s considerable benefit–and no harm—in loading up with plant-based foods,” notes study author Susan Levin, M.S., R.D., C.S.S.D., director of nutrition education for the Physicians Committee. “Large bodies of research show fruits, vegetables, and legumes offer a variety of protective properties, so why not move these foods to the center of our plates?”

The World Health Organization states that a significant percentage of cancers can be prevented by following a healthful diet, avoiding tobacco, leading an active lifestyle, and limiting alcohol intake.