Two important studies published today showed that the supplements taken by millions of Americans as vitamins don’t reduce the risk for many important diseases. The vitamins that people think it could help them fight the diseases don’t reduce the risk of heart attacks, strokes or breast cancer.

In one of the studies, 14,641 male physicians in their middle-age took vitamins E and C for eight years, but this didn’t show any improvement in their cardiovascular system. In the other study, 36,282 postmenopausal women were tracked during seven years when they took vitamin D and calcium. But this didn’t help to stop the risk for breast cancer.

Howard Sesso, who led the cardiovascular disease study that appeared in the Journal of the American Medical Assn., stated that half of the American adults take vitamin supplements every day but they should reconsider this treatment. Sesso, also an epidemiologist at Brigham and Women's Hospital in Boston and a professor at Harvard Medical School, added that "you don't know whether something is really true until you test it in one of these large-scale, long-term clinical trials."

In addition, Dr. David Heber, director of the UCLA Center for Human Nutrition, stated that the studies didn’t prove that the vitamins don’t work, but that they don’t work for certain diseases. Heber was not involved in the studies.

The team led by Sesso investigated the effect of 400 international units of vitamin E taken every day and 500 milligrams of vitamin C taken daily. From 7,315 people who had taken vitamin E, 620 had heart attacks and strokes, in comparison to the 620 people who had heart attacks when only took a placebo.

Dr. Rowan Chlebowski, a medical oncologist at the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, decided to make a study on vitamin D, which was said to reduce the risk of breast cancer.