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Daily Vitamin: Is It Really Necessary?

We're told the multivitamin is a prudent backup to the American diet. Here's how to decide for yourself.

December 04, 2006|Susan Brink and Sara Solovitch | Special to The Times

A multivitamin with the morning's calcium-fortified orange juice. A couple of vitamin C tablets to fend off that cold that's going around. A power bar for the commute into work, a sandwich with vitamin-fortified bread, a chewy caramel chock-full of calcium.

Before you know it, you've dosed yourself with five, six, maybe 10 times the recommended allowance for the day's nutrients.

"For years, dietitians have been saying, take a vitamin pill for insurance," says Chris Rosenbloom, professor of nutrition in the college of health and human sciences at Georgia State University. "But people are eating so many fortified foods now, I'm not sure it's still necessary."

She's not sure, because nobody is sure. Nearly 40% of Americans take supplements regularly, half of them taking a vitamin and mineral product, according to the Centers for Disease Control and Prevention, making supplements a $1.3-billion to $1.7-billion a year industry.

Yet despite an ever-proliferating array of supplements on store shelves, along with nutritionists' almost motherly urging to take them just to be on the safe side, there's little science to support America's love affair with vitamins.

Studies showing how well the body absorbs all those compounds sprinkled into Americans' cornucopia of fortified foods simply don't exist. And when a panel of experts with the National Institutes of Health examined studies of multivitamins last spring, they concluded that any evidence of their health benefit was thin, and that clinical trials were too short to determine any long-term effects.

"Essentially, if you don't take multivitamins, there's no reason to start," says Dr. J. Michael McGinnis, senior scholar at the Institute of Medicine and chair of the NIH state-of-the-science panel on the role of multivitamins. "If you do, there's no evidence to stop."

Adds Dr. Charles Halsted, editor of the American Journal of Clinical Nutrition: "You're deluding yourself if you think you're preventing a heart attack or cancer with a multivitamin. It's a waste of money if you're perfectly healthy and have a proper diet."

Those are fighting words for many believers -- and, indeed, the discussion can turn into a war of dueling studies, with defenders dragging out ones suggesting heart benefits or cancer prevention properties and skeptics citing others in which bright vitamin hopes have been dashed. "People sort of cherry-pick studies that they like," says Alice Lichtenstein, professor of nutrition science and policy at Tufts University. "You can find a study that supports almost anything."

Such conflicting studies fuel debates over high doses of specific vitamins, but few experts get rankled over the lowly multivitamin. After all, those who believe in vitamins point out that no one is at risk of overdosing by taking such a pill, even on top of fortified foods.

And, in fact, most nutrition experts -- and probably primary care doctors -- continue to say that taking a daily multivitamin pill is a sensible backup plan for the days people don't get all their fruits and vegetables, milk, cheese or yogurt, whole grain breads and cereals or meat, chicken, fish and legumes.

"I think all Americans -- adults, teenagers and children -- should be taking a multivitamin. Period," says Jeffrey Blumberg, professor of nutrition and director of the Antioxidants Research Laboratory at Tufts University.

Still, many in public health worry that a recommendation for a pill might signal to people that actual food isn't important.

"Does it suggest that, with a vitamin pill, you've got an insurance policy, and you don't need to be concerned about your diet?" asks Lichtenstein. Without convincing evidence to suggest benefit from a daily multivitamin, that's the wrong message.

Both camps agree, however, that significant problems come not with a basic multivitamin, which typically covers 100% of the recommended intake of the 13 compounds classified as vitamins and an assortment of minerals, but when people start thinking that if a little is good, a lot is better -- and ramp up their intake of a vitamin far past recommended levels.

"We're seeing a dose creep in the population," says McGinnis. "And in some cases, many, many-fold above the RDA."

Mixed messages

You can't blame people for being confused. Every week, it seems, some study appears in the literature raising a new vitamin hope or dashing an old one.

A sampling of the ping-ponging: A July 2005, study of almost 40,000 women that found that vitamin E supplements did not prevent heart disease and stroke in most women -- though they might provide some protection after age 65. The study also threw cold water on hopes that E could ward off cancer.

On the plus side, a 2005 study reported that vitamin E, along with vitamin C, beta carotene and zinc, helped ward off macular degeneration, the leading cause of vision loss in the elderly.

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