Multivitamins, Multi Questions

· The panel also said that one federally funded study of 3,600 people has shown benefits of taking high levels of the antioxidants vitamins A, C and E and also the mineral zinc to prevent some age-related vision loss , such as macular degeneration in people who already have early signs of the condition. In the study, participants took 500 milligrams of vitamin C, 400 IU of vitamin E, 15 milligrams of beta carotene and 80 milligrams of zinc daily. The vitamins reduced the risk of developed advanced macular degeneration by 25 percent. There was no effect in preventing cataracts.

· Calcium and vitamin D were also recommended for post-menopausal women . Both nutrients have been shown to help reduce the risk of bone fractures that often occur with osteoporosis. Current recommendations are for men and women 51 and older to consume 1,200 milligrams daily of calcium -- about the amount found in a quart of skim milk -- and 400 IU of vitamin D. Those 70 and older need 600 IU of vitamin D daily.

So if I eat fortified food and take a multivitamin, could I get too much of a good thing?

"We're concerned that some people may be getting too much of certain nutrients," said the panel's chair, J. Michael McGinnis. That's because a growing number of foods and drinks are fortified with vitamins and minerals. In 2005, the majority of Americans consumed fortified foods or beverages, which include bread, crackers, cereals, milk, eggs, juices and even fortified water. Among the nutrients whose consumption could easily exceed upper limits are vitamin A, high doses of which have been linked to an increased risk of osteoporosis. That's why experts say if you take a multivitamin, pick one whose ingredients don't exceed 100 percent of the daily value.

I read that as people age, some vitamins are not as well absorbed. What about that?

You're thinking of vitamin B12. After age 50, the stomach produces less acid; this reduces absorption of B12found naturally in food. But the crystalline form found in fortified food and in dietary supplements can be absorbed well at all ages. This is why the National Academy of Sciences recommends that people over 50either eat fortified food or take supplements. Many multivitamins contain 100 percent of the recommended daily intake, but the latest federal panel did not address vitamin B12in its report.

My multivitamin has lots of ingredients for which there is no daily value given, such as boron, lutein, lycopene and zeaxanthin. Are these useful or safe?

These ingredients are increasingly showing up in dietary supplements. They may have benefits (or hazards) that are suggested but not proven in the scientific literature. They may be there for marketing purposes, to set one multivitamin apart from the others on the shelf. In any case, the Institute of Medicine's Food and Nutrition Board has not set recommended dietary intakes for these substances.

Can multivitamins interact with drugs?

Adverse effects and drug or food interactions are enough of a concern that the panel recommended developing ways to understand and track them. These and other safety concern also prompted the panel to advise Congress to expand the Food and Drug Administration's "authority and resources to require manufacturers to disclose adverse events, ensure quality production and facilitate" consumers' reporting of adverse events. One suggestion: include information, including a toll-free telephone number to the FDA's Medwatch center, on dietary supplement labels.

So what's the bottom line?

Healthy eating. Food remains the best source of essential vitamins and minerals. Plus, scientists have found that something called food synergy--interaction that occurs between nutrients in food--that has yet to be duplicated by simply taking multivitamins. This may in part be due to the fact that food has lots of other nutrients that are still being identified and whose purpose is not yet known.

"I've always told my patients that [multivitamin] pills are not a substitute for food and healthy lifestyles," said Boston ophthalmologist Johanna Seddon, a co-author of the study that showed vision health benefits of taking antioxidants. "That hasn't changed." ·

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