In my recent NutritionFacts.org video Multivitamin Supplements and Breast Cancer I profiled a study of 35,000 women published last year that suggested that those who take multivitamins are placing themselves at increased risk for breast cancer. A recent review has cast doubt on this finding, but if it's true, American women are in effect paying $4 billion dollars a year to increase their breast cancer risk. And a study released yesterday suggests women may also be purchasing shorter lives.
The Iowa Women's Health Study followed 39,000 women for about 20 years and "found that several commonly used dietary vitamin and mineral supplements, including multivitamins, vitamins B6, and folic acid, as well as minerals iron, magnesium, zinc, and copper, were associated with a higher risk of total mortality. Of particular concern, supplemental iron was strongly and dose dependently associated with increased total mortality risk." This should not come as a shock to those who have been following the science with me over the years. For example, see my videos on copper, folic acid, iron, lutein, vitamin E, Herbalife®, Juice Plus+®, blue-green algae, and spirulina supplements.
The supplement industry likes to wave around studies showing that people with high levels of nutrients such as beta carotene in their bloodstream have lower disease risk. But where is beta carotene found in abundance? Carrots, sweet potatoes, and dark green leafy vegetables. High beta carotene blood levels are just a surrogate for a healthy diet. When people are given beta carotene in pill form, their cancer risk may actually go up. The editor-in-chief of the Archives of Internal Medicine wrote a commentary on the new study, concluding: “Because commonly used vitamin and mineral supplements have no known benefit on mortality rate and have been shown to confer risk….A better investment in health would be eating more fruits and vegetables….” With a few exceptions, we should try to get our nutrition from plants, not pills.
The leading trade association for the multi-billion dollar dietary supplement industry decried the study as a conspiratorial "hunt for harm," insinuating allopathic bias for being published in a journal of the American Medical Association. But last year an editorial published in the Journal of Alternative and Complementary Medicine also condemned the marketing of dietary supplements in North America as misleading, deceptive—even predatory. After examining hundreds of supplement manufacturers' claims, the review concluded: “Dishonesty or wild exaggerations are frequent occurrences in the marketing of supplements….The marketers of supplements like to use scientific evidence the way a drunk uses a lamp-post: more for support than illumination.”
In this morning's NutritionFacts.org video-of-the-day I share the story of my grandmother, illustrating that we don't need pills to live a long healthy life. It was her miraculous recovery—through diet—from terminal heart disease that inspired me to pursue a career in lifestyle medicine.
-Michael Greger, M.D.