With More and More Supplements, It’s Easy to Succumb to ‘Vitamania’
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.
Taking a daily multivitamin is “cheap insurance,” Liebman says. “It can’t hurt, and in some cases, it may fill in some deficiency that may occur.”
Some population groups, however, may benefit from selected supplements. Those older than 50, for example, might need an assist to boost absorption of vitamin B12, which is needed to prevent a certain type of anemia. Beginning at age 50, stomach-acid production starts to decline, making it more difficult to absorb this vitamin when it is bound to food--but not when it is ingested by supplement or when it is added to foods. By age 70, up to 30% of adults may be affected by this reduced absorption. Many also take drugs that can further suppress stomach-acid production, according to Irwin Rosenberg, director of the U.S. Drug Administration’s Nutrition Center at Tufts.
To combat that problem, the National Academy of Sciences recommended in 1998 that people 50 and older meet the dietary intake by eating B12-enriched foods or by taking a supplement with B12. Since red meat is one of the best sources of B12, vegetarians may also benefit from taking a vitamin B12 supplement regularly.
Women of childbearing age may also benefit from certain supplements, especially folic acid, which significantly reduces the risk of neural tube birth defects, including spina bifida, when given before conception. The academy recommends that all women of childbearing age take 400 micrograms per day of folic acid from fortified foods or supplements.
Seniors who spend little time outdoors often lack sufficient vitamin D, which is manufactured in the skin using ultraviolet light from the sun’s rays and is important for maintaining strong bones. Men and women age 51 and older need 1,200 milligrams per day of calcium, according to the academy. That works out to about four servings per day of dairy products--more than many older people consume.
Women and teens may also not get enough calcium in their diets to build strong bones and support a host of other body functions. National nutrition surveys show that many women and most teenagers also fall short on calcium consumption. Adolescent girls average 800 of the recommended 1,300 milligrams daily, according to the latest federal survey. Teenage boys come much closer, averaging nearly 1,200 milligrams per day.
experts caution against buying into “vitamania.” Swallow the latest vitamin claims about “miracle products” with a healthy dose of skepticism, they say. “We have a history of thinking about vitamins as magic bullets that can keep us healthy,” Liebman says. “They just have this aura of potency that isn’t always based in reality.”
Ultimately, it’s a risky proposition to fool with the body’s chemistry set without expert guidance. Vitamins and minerals can interact with each other, with foods and with drugs. In some cases, these interactions enhance absorption. In others, they block it.
Here are some guidelines to keep you safe and help you get what you need.
* Forget megadoses. There is no scientific proof that they help, and growing scientific evidence that they may cause harm, especially those containing large amounts of vitamin C or beta carotene. Megadoses of vitamins A, D, E and K are also among the most likely to interact with medications.
* Keep it simple. Many supplements now come in timed-release or sustained-release forms that often cost more than standard vitamins. A panel convened by the National Academy of Sciences found no benefit from their use.
* Consider your stomach. Take vitamins and minerals with food, unless otherwise indicated. For some supplements, like iron and calcium, this may mean reducing absorption, but taking them on a full stomach will reduce your risk of nausea or stomach irritation.
* Fat-soluble vitamins--A, D, E and K--are best absorbed with food containing some fat.
* Avoid the exotic. Some vitamin products now include herbs such as echinacea and other botanicals that promise to deliver a wide range of health benefits but have little scientific evidence to back their claims. The more varied the ingredients, the greater the risk of harm, says Benjamin Cabellero, director of the Center for Human Nutrition at Johns Hopkins University’s School of Public Health and Medicine in Baltimore.
* Avoid taking calcium at the same time as multivitamins or with supplements containing either iron or zinc. Calcium can bind to these substances and block their absorption. Better to cultivate the habit of taking the multivitamin every morning, for example, and calcium every night. This not only helps assure a more even dosage, but also may reduce interactions between vitamins, minerals and other drugs.
* Choose foods for enjoyment, not for their purported medicinal value. Go for balance and enjoyment because scientists still don’t know understand all the interactions in food that are beneficial.
