Americans want to believe in vitamin and mineral pills. We spent an estimated $10 billion on them in 2008, according to the Nutrition Business Journal.
But Consumer Reports on Health notes that recent studies undertaken to assess their benefits have delivered a flurry of disappointing results. The supplements failed to prevent Alzheimer's disease, cancer, heart attacks, strokes, type 2 diabetes and premature death.
While some people may need supplements at certain stages of their lives, nutritional deficiencies are uncommon in the U.S. Major health organizations for cancer, diabetes and heart disease all advise against supplements in favor of a healthful diet rich in fruits, vegetables, whole grains and legumes.
Another concern is that some vitamin pills can be toxic if taken in high doses for a long time. Studies show that beta-carotene pills, for example, can increase the risk of lung cancer in smokers, and a 2008 review suggests that the pills, plus supplemental doses of the vitamins A and E, may increase the risk of premature death.
Yet despite the unfavorable results, vitamin and mineral pills are widely used to fend off diseases. Consumer Reports on Health reviews the latest evidence on their effects.
SUPPLEMENTS STRIKE OUT
There is insufficient evidence to support the use of supplements to prevent the following conditions:
-- Cancer. In a large trial sponsored by the National Cancer Institute and published in 2009, researchers reported that vitamin E and the mineral selenium failed to prevent prostate cancer. In fact, researchers noted possible increased risks of prostate cancer from vitamin E, and of type 2 diabetes from selenium.
-- Heart disease. Folic acid and other B vitamins failed to prevent heart attacks, strokes, and death from cardiovascular disease in women at risk for heart disease in a 2008 trial by the Harvard Medical School. And neither vitamin C nor E prevented those events in men in the Physicians' Health Study II. Vitamin E, however, was linked to an increased risk of hemorrhagic stroke. Antioxidant supplements were previously thought to prevent fatty buildups in arteries, but research now suggests that they may worsen cholesterol levels and blunt the effects of cholesterol-lowering drugs.