Jul 01 (Reuters Health) - There is insufficient scientific evidence to support the notion that taking certain vitamins will prevent heart disease or cancer, the US Preventive Services Task Force announced Monday.

"This is not to say that we think people should not take vitamins," said Dr. Janet D. Allan, vice chair of the panel. "But the current evidence suggests -- for the vitamins that we studied -- that there is insufficient evidence to recommend that individuals take vitamin supplements for the prevention of cardiovascular disease or cancer."

Even so, Allan stressed that vitamin supplements may be an important part of nutritional health for pregnant women, those taking medications that may block nutrient absorption and the elderly, who may absorb inadequate amount of vitamins from food.

"People should strive to eat the healthiest diet possible," she said, while pointing out that nutrients from supplements may not offer the same benefits that they do when consumed as part of a healthy diet.

Before reaching their decision, the task force conducted an exhaustive review of studies that aimed to identify a risk reduction for heart disease or cancer among individuals who took vitamins A, C, E, multivitamins with folic acid or antioxidant combinations, Allan explained during an interview with Reuters Health.

The findings are published in the July 1st issue of the Annals of Internal Medicine.

The only negative recommendation concerned beta-carotene and the risk it may pose to people who smoke, according to the report. Previously, it was widely reported that smokers who take beta-carotene supplements may increase their risk for lung cancer. However, the risk was not seen among smokers who ate foods that contained the nutrient, such as carrots.

As such, the task force gave beta-carotene a grade of "D," or "recommends against," according to the report.

Vitamins A, C, E, multivitamins with folic acid and antioxidant combinations all received a grade of "I," signifying that there is "insufficient" evidence to make a recommendation for or against the use of these supplements for the prevention of cancer or heart disease.

Still, this report is unlikely to be the last word on the subject, according to Allan. She said that there are several ongoing clinical trials that are investigating if vitamin supplements can keep certain diseases at bay.

"In a few years, there will be more studies ... and they may provide new evidence," she said.

SOURCE: Annals of Internal Medicine 2003;139:51-70.