Living the WELL Life

A Look Back at a Year of Research - by Neal Barnard, M.D.

Sunday, January 23, 2011

Back when Christina and other experts first started advocating plant-based diets, the concept was new to so many people, including most doctors and researchers. But things are changing. Study after study has shown the benefits of plant-based diets and confirmed the risk of meaty diets. Here’s a look back at some of the research highlights from this past year.

A study in February’s American Journal of Cardiology confirmed the benefits of a low-fat vegetarian diet for the heart. A 12-week study, including 43 participants in Dr. Dean Ornish’s Multisite Cardiac Lifestyle Intervention Program showed that individuals who followed a low-fat vegetarian diet, along with a moderate exercise plan and stress management, measurably improved the function of their endothelium - the inner lining of arteries that is key to preventing heart attacks (Dod 2010).

An Italian study in Cancer Causes and Control showed that diets rich in fruits and vegetables reduce the risk of pancreatic cancer. Those who consumed the most fruits and vegetables had an estimated 40 percent decreased risk, compared with those who ate the least. The study found that frequent meat consumption doubles risk, and that table sugar and white potatoes also increase risk (Polesel 2010).

Last year, researchers also found new evidence that plant foods can help fight breast cancer. In a study published in the American Journal of Epidemiology, researchers followed the diets of 51,928 participants in the Black Women’s Health Study. Participants who ate two or more servings of vegetables per day had a 43 percent decreased breast cancer risk, compared with those who ate less than four servings per week. Cruciferous vegetables like broccoli, cauliflower, and kale and carrots had the largest impact on breast cancer risk (Boggs 2010).

Kidney patients got a real benefit from vegetarian diets, according to a study in the Clinical Journal of the American Society of Nephrology. Those who followed vegetarian diets had lower serum phosphorous levels, compared with those who consumed meat. Maintaining normal phosphorous levels is critical for patients with chronic kidney disease and is typically controlled by restricting intake (Moe 2010).

Researchers also found more evidence that animal protein is harmful to bone health. In Beijing, China, 757 girls were studied; results showed that animal protein, especially from meat and eggs, was negatively associated with bone mineral density and content (Zhang 2010).

For all those who worry that soy is somehow linked to cancer, yet another study confirms that soy products actually have an anticancer effect. The Canadian Medical Association Journal reported that women consuming the most soy products had a lower risk of breast cancer recurrence, compared with women who neglect soy. Postmenopausal women who ate more than 42.3 milligrams of soy isoflavones daily had a 33 percent decreased risk of recurrence, compared with women who ate less than 15.2 milligrams per day. Eight ounces of soymilk contains roughly 20 milligrams of soy isoflavones (Kang 2010).

And for all those people who thought we needed fish oil, it appears that the advantages of fish oil have been overblown, according to reports in the New England Journal of Medicine and the Journal of the American Medical Association. As part of the Alpha Omega Trial, Dutch researchers followed 4,837 patients between the ages of 60 and 80 who had suffered from heart damage up to ten years prior to the study. Participants were given one of four margarines to consume over a 40-month period. Three of the margarines contained omega-3 fatty acids in the forms ALA, EPA-DHA, and EPA-DHA and ALA, and the fourth was a placebo. No significant benefit was seen among the groups (Kromhout 2010).

Researchers in England found that fish oil did not benefit the cognitive function of elderly adults after two years of daily supplementation (Dangour 2010).  And pregnant women who consumed 800 mg of a DHA-rich fish oil supplement each day during pregnancy showed no benefits for depression, and their babies did not differ cognitively from children born from women who consumed a vegetable oil (rapeseed, sunflower, and palm) supplement (Makrides 2010).

Meanwhile, researchers with the European Prospective Investigation into Cancer and Nutrition (EPIC) Study found, surprisingly enough, that women following vegan diets had significantly more omega-3 “good fats” in their blood, compared with fish-eaters, meat-eaters, and ovo-lacto vegetarians. Levels in vegan men were not quite as high as in vegan women. Vegan participants converted robust amounts of shorter-chain fatty acids into these long-chain fatty acids. The study included 14,422 men and women aged 39 to 78 (Welch 2010).

It’s clear that the diet Christina began advocating decades ago is still the best for our health. I look forward to even more exciting research about vegan diets in this New Year. 
Neal Barnard, M.D., is the president of the Physicians Committee for Responsible Medicine.

Dod HS, Bhardwaj R, Sajja V, et al. Effect of intensive lifestyle changes on endothelia function on inflammatory markers of atherosclerosis. Am J Cardiol. 2010;105:362-367.

Polesel J, Talamini R, Negri E, et al. Dietary habits and risk of pancreatic cancer: an Italian case-control study. Cancer Causes Control. 2010;21:493-500.

Boggs DA, Palmer JR, Wise LA, et al. Fruit and Vegetable Intake in Relation to Risk of Breast Cancer in the Black Women's Health Study. Am J Epidemiol. Published ahead of print October 11, 2010. doi: 10.1093/aje/kwq293.

Moe SM, Zidehsarai MP, Chambers MA, et al. Vegetarian compared with meat dietary protein source and phosphorus homeostasis in chronic kidney disease. Clin J Am Soc Nephrol. Published ahead of print December 23, 2010. doi:10.2215/CJN.05040610.

Zhang Q, Ma G, Greenfield H, et al. The association between dietary protein intake and bone mass accretion in pubertal girls with low calcium intakes. Br J Nutr. 2010;103:714-723.

Kang X, Zhang Q, Wang S, Huang X, Jin S. Effect of soy isoflavones on breast cancer recurrence and death for patients receiving adjuvant endocrine therapy. CMAJ. Published ahead of print October 18, 2010: doi:10.1503/cmaj.091298.

Kromhout D, Giltay EJ, Geleijnse JM. n-3 fatty acids and cardiovascular events after myocardial infarction. N Engl J Med. Published ahead of print August 29, 2010: doi: 10.1056/NEJMoa1003603.

Dangour AD, Allen E, Elbourne D, et al. Effect of 2-y n23 long-chain polyunsaturated fatty acid supplementation on cognitive function in older people: a randomized, double-blind, controlled trial. Am J Clin Nutr. Published ahead of print April 21, 2010. doi: 10.3945/ajcn.2009. 29121.

Makrides M, Gibson RA, McPhee AJ, et al. Effect of DHA Supplementation During Pregnancy on Maternal Depression and Neurodevelopment of Young Children. JAMA. 2010;304:1675-1683.

Welch AA, Shakya-Shrestha S, Lentjes MAH, Wareham NJ, Khaw KT. Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of a-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. Am J Clin Nutr. 2010;92:1040-1051.


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