A recent study by several researchers at Harvard Medical School and Brigham and Women's Hospital found that long-term multivitamin use may decrease colon cancer rates in women by up to 75 percent.

"We assessed folate intake over a number of years," said co-author Meir J. Stampfer, associate professor of medicine and of epidemiology and nutrition at the School of Public Health (SPH). "We found that people who had high levels of folate [intake], particularly over long durations, had lower risks of colon cancer."

The article, published in the Oct. 1 issue of the Annals of Internal Medicine, details the results of a 15-year study of 121,700 registered nurses. The researchers, headed by SPH Assistant Professor of Medicine in the Department of Nutrition Edward L. Giovannucci, found that of the 88,756 nurses eligible for the study, those who had taken multivitamin substitutes containing folic acid, otherwise known as folate, for more than 15 years had a markedly lower chance of getting colon cancer.

The study suggested that a lack of folic acid could increase the chances of abnormalities in either "DNA synthesis or repair," thereby increasing the chances of colon cancer.

The study found that those women whose daily folate intake exceeded 400 micrograms due to continued use of multivitamin supplements for more than 15 years reduced their risk of getting colon cancer by 75 percent.

Interestingly, the correlation was much stronger among women who took supplements than among those with high intakes through natural sources.

Researchers theorize that this difference may be due to the fact that the body can utilize folate from supplements more efficiently than folate from food.

Those who had taken folate supplements for less than 15 years were also significantly less likely to have reduced colon cancer rates.

The study focused exclusively on women. The article does note another study that found that "men who used supplements for more than 10 years had a moderately reduced risk for colon cancer."

Some Harvard students interviewed yesterday said that vitamin supplements are already a part of their diet.

Jill Macquarrie '00 of Lowell House said she takes the multivitamin Centrum because "it sort of guarantees that you get everything."

Alex E. Washington, a student at the Harvard Business School, also takes Centrum "to make sure that I'm getting everything-especially eating around here."

But Teresa Fung, nutrition consultant for Harvard Dining Services, said that the food in Harvard's dining halls provide enough folate to protect students from the dangers of colon cancer.

"A balanced, healthy selection of foods from what is offered in the dining halls would have no problems in providing what a person needs nutritionally," Fung wrote in an e-mail. "The important point is what one chooses to eat. Under normal circumstances, supplementation is not necessary.

"The best sources of folate are green leafy vegetables, beans, and now anything that is made with flour is [fortified] with folate," Fung added. "The level of fortification is aimed to provide about 400 micrograms of folic acid in the diet if one eats about 6-11 servings of grains a day."