Several recent studies have cast doubt on the effectiveness of high doses of vitamins to help prevent heart disease in men, as well as some cancers in women. VOA's Melinda Smith has details on the findings, published in the Journal of the American Medical Association.
Millions of people around the world buy vitamins, hoping they will provide an extra boost to their health. But do they really help?
Vitamins C and E are two of the most popular.
Both are found in fruits and vegetables. They are believed to protect cells, tissue and organs in the human body.
But a new study discounts the effectiveness of these vitamins in helping prevent cardiovascular disease.
In the study, 14,000 men took high doses of C and E. All of them were doctors and were 50 years of age and older.
Most were at low risk for heart disease and stroke.
Howard Sesso and Dr. J. Michael Gaziano of Brigham and Women's Hospital in Boston, Massachusetts conducted the study.
"In selecting physicians, it also enables us -- with their excellent ability to provide medical information, risk factors, compliance and other relevant information for the trial -- to track their health status over a long period of time," Sesso said.
The physicians participated in the study for almost a decade. The study concluded there was no proof that either C or E made a difference in the prevention of cardiovascular disease.
Dr. Gaziano says the findings demonstrate that taking care of your body involves more than taking a capsule.
"We should stick with the fundamentals, like stopping smoking and eating a good diet and exercising regularly and treating blood pressure and lowering cholesterol levels," he said.
B vitamins are considered essential to a healthy diet. B-6 helps protect the body's immunity. B-12 is good for the brain and nervous system.
But another recent study followed at least 5,000 women over the age of 40.
It showed that B vitamins did nothing to reduce the risk of cancer, specifically cancer of the breast and colon.
"It was surprising that there was no evidence of any cancer benefit," said Dr. JoAnn Manson. She is also with Brigham and Women's Hospital. "Because some previous studies had suggested that at least a diet that is high in folate and B vitamins might be protective against cancer," she added.
Recent studies have also found that many people with low levels of vitamin D are at risk for a number of diseases. Those range from certain cancers to diabetes and heart problems.
Yet one study of 36,000 older women showed no difference in the prevention of breast and colon cancer.
Some researchers say participants in the study should have taken higher doses of vitamin D than the 400 daily international units they were given.
Other researchers warn that some patients may be shortening their lifespan by taking higher than recommended doses of certain vitamins.
Eating a healthy diet full of natural vitamins may be a lot safer, they say, than swallowing supplements.
Some Video Courtesy of : Journal of the American Medical Association