Vitamins a good insurance policy

It's estimated that half of all American adults take a daily vitamin supplement. Yet, in spite of the popularity of the pills, many wonder whether they're good for our health.

CNN learned more about vitamins from Dr. George Blackburn, director of the Center for Study of Nutrition and Medicine at Beth Israel Deaconess Medical Center in Boston, Massachusetts.

CNN: What do you say when asked by patients whether they should take vitamins?

Blackburn: I say take a simple, once daily vitamin or mineral that costs about 7 or 8 cents as insurance, not to help their health or treat a disease but to ensure that they don't have a vitamin/mineral deficiency. (Health Minute: Watch to learn more about the benefits of vitamins and supplements Video )

CNN: Is that general advice for a healthy person?

Blackburn: I think it's important to realize that most people taking vitamins and minerals are healthy. Very few Americans are sick other than for a short time and therefore they should be concentrating on a healthy diet: fruits, vegetables and whole grains. Unfortunately, only 25 percent of Americans do that, so it's for them that we want the once daily vitamin/mineral.

CNN: What about taking calcium and folic acid supplements?

Blackburn: We've built some of it into the food supply. Now the flour we get has folic acid in it that takes care of most of the folic acid problem. We're now facing a shortage of calcium and vitamin D. We prefer three servings [daily] of low-fat dairy, yogurt, and cheese. We're learning that we may need more vitamin D. If we see a person isn't getting a good supply of dairy and dark green vegetables we definitely are urging that they take a calcium supplement and a vitamin D supplement.

CNN: Are we at risk of getting too many vitamins because of fortified foods?

Blackburn: I don't think the fortification, the intake of vitamin and mineral fortification of food, has been other than good so far. It's not likely that a person is going to overdose in a food fortification. You would have to be taking a high dose, single supplement to worry about overdose.

CNN: Are natural vitamins better than synthetic?

Blackburn: They are the same. It doesn't matter when they are absorbed into the body whether they were synthetic or natural sources; most supplements are synthetic.

CNN: Is there any scientific proof that vitamin supplements are a magic bullet?

Blackburn: Any claim to preventing disease or extending life with vitamin/mineral supplements is unproved.

CNN: So what's your advice to patients who can't decide whether to take a vitamin supplement?

Blackburn: Concentrate on eating a healthy diet with dark green vegetables, whole grains and fruits. Start your day with a healthy breakfast and watch your portion control. If you're physically fit and eating a healthy diet you'll get things that are not in any supplement. The good news for people looking at supplements, if they just stay with one multivitamin a day they'll be safe.

by:Judy Fortin is a correspondent with CNN Medical News. Accent Health reporter Linda Ciampa contributed to this report.