Do Vitamin Supplements Make Sense?
WebMD News Archive
The body turns beta-carotene into the antioxidant vitamin A.
Foods rich in beta-carotene, such as leafy greens and orange and yellow vegetables, lower the risks for cancer and heart disease. But studies show beta-carotene supplements don’t lessen cancer or heart disease risks in healthy adults and may raise the risk of lung cancer in smokers and people exposed to asbestos.
Vitamin B12 helps the body make red blood cells. It also aids nerve and brain function.
B12 is bound to the protein in animal products. Younger adults usually get plenty of this key nutrient by eating meat, poultry, fish, eggs, milk, and fortified cereals.
Older adults lose the ability to separate B12 from protein, which can cause a deficiency. The Institute of Medicine recommends that adults over age 50 take B12 supplements, which are easier to absorb. Vegetarians who don’t eat breakfast cereals may also need supplements.
Studies have found that eating fish rich in omega-3 fatty acids lowers the risk of heart attacks and strokes, but the evidence supporting the use of fish oil supplements is mixed.
A large research review published last year in the Journal of the American Medical Association found that people taking fish oil pills didn’t have lower rates of heart attacks, strokes, or deaths compared to those who took placebo pills. According to the researchers, while many of these large studies have limitations, the results did not seem to justify the use of omega-3 supplements as an intervention for heart disease prevention in some people.
Why might eating fish be better than taking fish oil? Experts say that like all whole foods, fish are complex mixtures of vital nutrients. It could be that all those nutrients work together to provide the benefit. Or it may be that fish replaces less healthy sources of protein in the diet, like red meat.
Until more is known, experts say there doesn’t seem to be any harm in taking fish oil, as long as you don’t mind spending the money.
Doctors had high hopes that vitamin E might prevent cancer and heart disease, but the best studies of vitamin E have failed to show benefits from taking supplements. Instead, some studies have suggested that taking large doses of vitamin E might be risky.
One large trial randomly assigned more than 35,000 men to take vitamin E, selenium, both supplements, or a placebo pill. After seven years, doctors found that men who took vitamin E were about 17% more likely to develop prostate cancer compared to those taking the placebo.
Another study that randomly assigned 10,000 men and women at high risk for heart disease to take either vitamin E or a placebo daily for almost five years found no differences in the numbers of deaths, heart attacks, or strokes between the groups.