As science finds exciting new roles for a growing number of vitamins and minerals, many consumers mistakenly ask not whether they need extra doses of these nutrients but how much of these popular dietary supplements they should take.
Mistakenly, because most research links the beneficial effects of vitamins and minerals to food--not pills. In fact, several recent large, well-designed scientific trials have found some vitamin supplements pose real danger, especially to particular groups of people.
"Dietary supplements are just what they say they are," says Jeffrey Blumberg, associate director of the U.S. Department of Agriculture's Human Nutrition Research Center on Aging at Tufts University in Boston. "They are supplements to, not substitutes for, a healthy diet."
Tantalized by supplement makers' promises of everything from stronger bones to reduced stress, an estimated 40% of Americans have taken a vitamin or mineral supplement during the last month, according to the latest federal National Health and Nutrition Examination Survey. Sales of supplements totaled nearly $5 billion annually in 1998, according to the San Diego-based Nutrition Business Journal, and were rising at about 18% per year, according to the journal. At that time, about 23 million regular supplement users spent more than $20 a month on vitamins, minerals and herbs, the journal reported.
But the research on vitamins and minerals is simply too extensive to pare down to a small guide. Check with your doctor before taking any dietary supplements.
Not long ago, dietary supplements were commonly viewed as an either/or proposition: Either consume a healthful diet or take vitamins and minerals, nutritionists advised. Today, most experts concede that you can't eat unwisely and then expect a vitamin or mineral pill to make up for missing nutrients.
"Americans have been misled by a long-standing marketing scam that leads us to believe that if you take a vitamin, you can eat junk food and make up for it," says Bonnie Liebman, director of nutrition for the Center for Science in the Public Interest, a Washington-based consumer group. "Vitamins and minerals can't make up for a lousy diet."
This federal survey and other nutrition surveys suggest that many Americans don't eat five servings a day of fruits and vegetables as advised by the National Cancer Institute, and many don't meet the recommended dietary guidelines for sound nutritional intake. Some experts, such as Liebman, hedge their dietary bets: They try to eat good foods and then add a daily multivitamin--one that provides no more than the recommended allowances for vitamins and minerals.
