Vitamins: Separating Fact From Fiction (cont.)

Why They Matter

Vitamins and minerals are substances your body needs for normal growth and functioning. Some facilitate crucial chemical reactions, while others act as building blocks for the body.

Nutritionists call vitamins and minerals "micronutrients" to distinguish them from the macronutrients such as proteins, carbohydrates, and fats that make up the bulk of our food. While micronutrients are vital for the proper processing of macronutrients, they're needed in smaller quantities. Think of it this way: If macronutrients are the gas in your engine, then micronutrients are like the motor oil, coolant, and battery fluid.

Micronutrient deficiency can lead to acute diseases with exotic names like scurvy, pellagra, and beriberi. Deficiency diseases were common in the U.S. until the 1940s, when the FDA-mandated fortification of common foods like bread and milk. These diseases are still common in many poorer countries.

Maintaining a Healthy Diet

It's easy to get enough micronutrients from your food if you maintain a healthy diet, Audrey Cross, PhD, associate clinical professor of nutrition at Columbia's School of Public Health, tells WebMD. But most people fail that test; they'll eat two or three servings of fruits and veggies per day rather than the recommended five. That's why Cross (and many other nutritionists) suggest a multivitamin as a sort of nutritional safety net for many of their patients.

But it's just a safety net. So-called "whole foods" like veggies and whole grains contain fiber and a host of other important nutrients that can't be adequately delivered through pills. In fact, scientists are still finding new "trace elements" in whole foods that may someday be labeled essential to health -- but aren't found in any pill.

"There are literally thousands of these compounds, and we're just scratching the surface on knowing what their role is," says David Grotto, a registered dietitian and spokesman for the American Dietetic Association. "We're sending the wrong message if people believe they've got everything under control and if they're taking vitamins while eating a horrible diet."

Choosing a Supplement

It's easy to become overwhelmed when looking at the dietary supplement shelves of a health food store or even your local supermarket. While many of the health claims are unproven or downright bogus, some supplements may be useful for some groups.

Major multivitamin makers typically produce different varieties for men, women, children and older folks. Picking a pill that fits your group makes sense, says dietitian Grotto, as the optimal level of various nutrients varies by age and sex. For example, premenopausal women need more iron than children or the elderly, he says.

But the elderly have a harder time obtaining adequate amounts of vitamin B-12 from natural sources, so the need for supplementation may increase with age, says Lynn Bailey, a University of Florida nutritionist who teaches courses on vitamins.