Do supplements really help?

In an ideal world, no one would need dietary supplements. Our balanced diets would provide all the vitamins, minerals and other nutrients our bodies need.

Alas, the world of American eating is far from ideal. And that, some nutrition experts and supplement advocates argue, is why we need dietary supplements.

The latest federal data show that more than half of U.S. adults use dietary supplements, mostly multivitamins. But do we really need all those pills?

Depends on whom you ask. The latest version of the federal Dietary Guidelines for Americans urges us to get our nutrients primarily from food:

"A fundamental premise of the Dietary Guidelines is that nutrients should come primarily from foods. Foods in nutrient-dense, mostly intact forms contain not only the essential vitamins and minerals that are often contained in nutrient supplements, but also dietary fiber and other naturally occurring substances that may have positive health effects."

This "food first" approach is based on the emerging understanding that our bodies may process nutrients in food differently from those supplied by supplements and that foods contain scores of compounds whose synergy may be what makes them good for us.

But meeting your daily dietary needs without using supplements is a challenge, even when you're choosing ultra-healthful foods under a professional dietitian's guidance.

Robert Post, deputy director of the U.S. Department of Agriculture's Center for Nutrition Policy and Promotion, says too few Americans are meeting all their nutritional requirements and that dietary supplements, used sensibly, can help fill gaps in our diets.

But Post, like the guidelines, calls for people to get their fill of those four nutrients from food and to consider supplements only for a handful of dietary deficiencies related to our stage of life and dietary preferences. Those include:

Iron: Women who are able to become pregnant need more iron, especially heme iron, which the body absorbs more readily than non-heme iron. Heme iron is found in lean meat and poultry; non-heme iron is in white beans, lentils, spinach, enriched breads and cereals. Foods rich in Vitamin C can aid iron absorption. Adult males need just 8 mg of iron per day; women need 18 mg, and pregnant women need 27 mg.

Folate : Women who can bear children also should eat more foods containing folate, such as beans, peas, oranges, orange juice and dark-green leafy vegetables such as spinach, kale and mustard greens. Because folate and folic acid (the nutrient's synthetic form) help prevent neural-tube defects in infants, women who can become pregnant should consume 400 micrograms of folic acid (from fortified foods or supplements); pregnant women should consume 600 mcg of folic acid daily.

Vitamin B12: Some people age 50 and older have trouble absorbing Vitamin B12 from food. To compensate, people 50 or older should increase consumption of cereals fortified with this vitamin or take supplements of it. Because B12 occurs naturally only in animal-based protein, vegetarians and vegans also should eat fortified cereals or take supplements. Most adults need 2.4 mcg per day.