Consumer Reports recently identified hazards that might surprise the large swath of American adults - more than 50 percent - who take vitamins, herbs or other nutritional supplements.
The list of hazards was distilled from interviews with experts, published research and CR's own analysis of reports of serious adverse events submitted to the Food and Drug Administration, obtained through a Freedom of Information Act request.
The hazards CR found include:
. Supplements are not risk-free. More than 6,300 reports describing an excess of 10,300 serious outcomes - including 115 deaths, more than 2,100 hospitalizations, 1,000 serious injuries or illnesses, 900 emergency-room visits and some 4,000 other important medical events - streamed into the FDA from supplement companies, consumers, health care providers and others between 2007 and mid-April 2012. The reports by themselves don't prove that supplements caused the problems, but the raw numbers are cause for concern. Current laws make it difficult for the FDA to order a problem product off the market.
To protect yourself, search the FDA's website at www.fda.gov for warnings, alerts or voluntary recalls involving a supplement you are thinking of taking. If you suspect you're having a bad reaction to a supplement, tell your doctor.
. Some supplements are really prescription drugs. According to Daniel Fabricant, Ph.D., director of the FDA's Division of Dietary Supplement Programs, dietary supplements spiked with prescription drugs are the "largest threat" to consumer safety. Many recalled products have the same or similar active ingredients as prescription drugs such as sildenafil (Viagra), tadalafil (Cialis) and sibutramine (Meridia, a weight-loss drug that was removed from the market in 2010 because of evidence that it increased the risk of heart attacks and strokes). Others contained synthetic steroids. To protect yourself, consult your doctor if you are having trouble in the bedroom (it could indicate an underlying health problem).
. You can overdose on vitamins and minerals. Unless your health care provider tells you that you need more than 100 percent of the recommended daily intake of a particular nutrient, you probably don't. Mega-doses of the fat-soluble vitamins A, D, E and K can cause problems, and even some standard doses may interfere with certain prescription medicines.
. You can't depend on warning labels. For one thing, the FDA doesn't require them on supplements with one important exception: iron. In a market-basket study of 233 products purchased online and in the New York City metropolitan area, CR found wide variations and inconsistencies in labeling. To protect yourself, make sure your doctor or pharmacist knows what supplements and prescription drugs you are taking or thinking of taking.
. Heart and cancer protection: not proven. Omega-3 pills and antioxidants are widely thought to reduce the risk of heart disease and cancer, respectively, and millions of women take calcium to protect their bones. But recent evidence casts doubt on whether those supplements are as safe or effective as assumed. The report notes that the widely held view that fish-oil pills help prevent cardiovascular disease hit a snag when a study of 12,500 people with diabetes or pre-diabetes and a high risk of heart attack or stroke found no difference in the death rate from cardiovascular disease or other outcomes between those given a one-gram fish-oil pill every day and those given a placebo. These findings were published in a June 11 online report from the New England Journal of Medicine.
. CR also notes a recent blow against calcium supplements by German and Swiss researchers who followed almost 24,000 adults for an average of 11 years. They found that regular users of calcium supplements had an 86 percent increased heart attack risk compared with those who didn't use supplements, the June issue of the journal Heart reported.
Vitamins and supplements are not risk-free and can be dangerous.