"Should I take vitamin pills every day? I'm in good health and want to stay healthy."
Just try to find an answer based on the kind of scientific study used to see if new drugs are safe and effective.
Clinical trials comparing the health of people who take vitamins and people who don't often give clear answers.
Some have found that vitamin supplements protect against diseases. Some have found no benefit. Still others found hints of harmful effects. A landmark 1996 study of beta-carotene in cigarette smokers, for instance, found that the nutrient supplement actually increased the risk of lung cancer.
On one hand, scientists report that vitamin pills can reduce the risk of heart disease, cancer and other conditions. On the other, guidelines from government agencies and health organizations often recommend that healthy people get vitamins from a good diet.
People are left to decide for themselves.
About three out of every 10 Americans take vitamin pills regularly. The cost can range from a few dollars a month for inexpensive generic vitamins to hundreds for boutique "natural" vitamin supplements taken in mega-doses.
A wise investment in health? A waste of hard-earned money? Or risky business that may actually increase the risk of some diseases?
The New England Journal of Medicine asked two world authorities on nutrition what they would advise patients about taking vitamin pills. Dr. Walter C. Willett and Dr. Meir J. Stampfer of Harvard University weighed the scientific pros and cons about vitamin pills in a report published last November.
They concluded that many people do not consume ample amounts of vitamins in their diet.
Women who could become pregnant, for instance, may not get enough folic acid to reduce the risk of certain birth defects. More folic acid may help adult men and women reduce their risk of heart attacks, colon cancer, and breast cancer.
Older people often don't get enough vitamin D in their diets. Some studies show that half of older adults are deficient in vitamin D. Older people also don't absorb vitamin B12 as easily as younger people.
Vegetarians may need more vitamin B6; cigarette smokers more vitamin C; people who drink alcoholic beverages daily need more folic acid; and few adults get enough vitamin E.
Willett and Stampfer suggested a simple solution. Take one multi-vitamin tablet daily, and get 100 percent of the Recommended Daily Allowance (RDA) of 11 vitamins needed for good health. Multi-vitamins often contain minerals, as well, although the levels of some - especially calcium - may be below recommended levels.
The single-pill-a-day approach can have a big impact on health for pennies a day, they said.
Older people who took a multi-vitamin supplement, for instance, had 50 percent fewer days of illness due to infections. In other studies, adults who took a multivitamin had a lower risk of heart disease, colon cancer and breast cancer.
Typical cost: Less than $50 a year for store-brand multi-vitamins.
In addition, Willett and Stampfer recommended that middle-aged and older adults take 400 International Units (IUs) of vitamin E each day. Multi-vitamins may contain only the RDA of vitamin E, which is 30 IUs. They cited strong evidence that higher levels can reduce the risk of heart attacks by 20 to 40 percent.
The experts emphasized that vitamin pills are no substitute for a healthy diet and won't erase the risks of cigarette smoking, obesity and lack of exercise.
Fresh fruits and vegetables and other foods contain other important nutrients, aside from vitamins. Those include fiber and natural chemicals that protect the body from diseases.