More On Vitamins

by Gina Kolata

But is more better?

(Ed. Note: After they were first identified and a name was sought for the group of compounds, "vita" ((for life)) and "min" ((small amount)) made an excellent choice for vital substances needed in small quantities.)

(From The New York Times)

A growing number of medical experts are concerned that Americans are overdoing their vitamin consumption. Up to 70 percent of the population is taking supplements, mostly vitamins, convinced that the pills will make them healthier.

But researchers say that vitamin supplements cannot correct for a poor diet, that multivitamins have not been shown to prevent any disease and that it is easy to reach high enough doses of certain vitamins and minerals to actually increase the risk of disease.

No longer, the experts say, are they concerned about vitamin deficits. Those are almost unheard of today, even with the population eating less than ideal diets and skimping on fruits and vegetables. Instead, the concern is with the dangers of vitamin excess.

"There has been a transition from focusing on minimum needs to the reality that today our problem is excess - excess calories and, yes, excesses of vitamins and minerals as well," said Dr. Benjamin Caballero, a member of the Food and Nutrition Board at the National Academy of Sciences and the director of the Center for Human Nutrition at Johns Hopkins University.

Caballero said that for some supplements, including vitamin A, the difference between the recommended dose and a dose that could lead to bad outcomes like osteoporosis was not large. Popular multivitamins, he added, often contain what could be risky doses. "Certainly," he said, "by consuming supplements, people can reach that level."

Doctors who once told patients that multivitamins were, at worst, a waste of money now say they are questioning that idea.

"All of a sudden, scientists are rearing back and saying, 'Wait a minute, do we really know that we need this and do we really know that we need that?"' said Dr. Ruth Kava, nutrition director at the American Council on Science and Health, a consumer foundation in New York that is in part financed by industry.

With vitamin A in particular, it is easy to step over the edge into a danger zone, said Dr. Joan McGowan, chief of the musculoskeletal diseases branch at the National Institute of Arthritis and Musculoskeletal and Skin Diseases.

"You can be eating Total cereal, drinking fortified milk, taking a multivitamin," McGowan said. "You can get into a situation where you're getting more than you need. Until recently, there was little concern about vitamin A and bone health." Now, she added, "we may have to rethink the issues."

Similar questions are being raised about other vitamins and minerals, notably iron and vitamins E and C. Researchers say the questions involve multivitamins taken by healthy people, not specific vitamins or minerals taken by groups with specific needs.

Some elderly people, for example, may be deficient in vitamin B12 because they lose their ability to absorb it from foods. People who spend little time outdoors may require vitamin D, which the skin makes when it is exposed to sunlight. Even when older people are in the sun, aging skin loses much of its ability to synthesize the vitamin.

Pregnant women who do not receive enough folic acid, a vitamin in fruits and vegetables that is added to enriched flour, are at increased risk of having babies with neural tube defects. Because the vitamin is needed at the very start of pregnancy, some advocate folic acid supplements for all who might become pregnant, just to be sure they are protected.

The most popular individual supplements are vitamins C and E, said Dr. Robert M. Russell, the director of the Human Nutrition Research Center of the Agriculture Department at Tufts University, and head of the Food and Nutrition Board. Scientists once thought those vitamins could help prevent ailments like cancer and heart disease, but rigorous studies found no such effects.

Vitamin E supplements can increase the risk of heart attacks and strokes, and studies of vitamin C supplements consistently failed to show any beneficial effects.

"The two vitamins that are the least needed are the ones most often taken," Russell said.

Excess vitamin C is excreted in the urine, but excesses of some other vitamins are stored in fat, where they can build up.

While readily noting that the proof of a benefit is not in, some researchers said they took multivitamins. They agree with Dr. Joann E. Manson, chief of preventive medicine at Brigham and Women's Hospital in Boston, who takes a multivitamin and recommends it to patients whose diets seem unbalanced.

"I think it's a good form of insurance," Manson said. "I don't think there's a significant downside."

Others decided against taking the pills. Kava, of the American Council on Science and Health, said she abstained.
"People ask me what vitamins I take," she said. "I say I don't take any. They look at me askance. They can't believe I'm a nutritionist."

Caballero also does not take vitamins. "There is no disease I know of that is prevented by multivitamins," he said. In fact, Caballero said, typical pills, which contain a variety of minerals as well as vitamins, have ingredients that actually cancel out one another.

"Minerals antagonize each other for absorption," he said. "Zinc competes with iron, which competes with calcium." Caballero also notes that large, rigorous studies that were supposed to show that individual vitamins prevented disease ended up showing the opposite. Those who took the vitamins actually had more of the disease they were meant to prevent.

Two large randomized trials of vitamin A and beta carotene that researchers hoped would show a protective value against cancer found no benefit, and one found that participants who took the supplements had more cancer. A large study of vitamin E and heart disease found that it did not prevent heart attacks and that people taking it had more strokes.

Another study, of women with heart disease, found that antioxidant vitamins might actually increase the rate of atherosclerosis.

Caballero said people were deluding themselves if they thought multivitamins could make up for poor diets. "If you eat junk food every day, vitamins are the least of your problems," he said.

"We don't know what ingredient in a healthy diet is responsible for which condition. We do know that people who consume five servings or more of fruits and vegetables have less disease. But we don't know which ingredient. We tried beta carotene, vitamin E and antioxidants, and they didn't work. People are looking for the magic bullet. It does not exist."