There's been a lot of excitement about antioxidants - nutrients that protect the body from damage due to "free radicals," which are compounds produced by environmental toxins and normal body processes. Free radicals can damage cells throughout the body. There have been many claims about what antioxidants can do for our health, including protecting us from heart disease, cancer, and Alzheimer's disease. Vitamins C and E, beta-carotene (vitamin A), and the mineral selenium are well-researched antioxidants.
Early studies showed that people who ate lots of fruits and vegetables - foods rich in antioxidants - were less likely to develop such diseases than those who shunned these foods. Next, people already taking antioxidant pills were compared to others who weren't taking such supplements. Again, the antioxidants seemed to be protective. But were they really? Taking a closer look at these studies, it's likely that people who choose to eat lots of fruits and vegetables or take supplements are more health-conscious than those who don't; this may explain these impressive results. Also, fruits and vegetables offer many more nutrients than the few antioxidants we know about.
The best studies are "clinical trials," where people are randomly assigned either antioxidants or a placebo (a dummy tablet). That way, the only difference between the two groups is whether they're getting the antioxidant or not - participants (and usually researchers as well) don't know which group they're in. As it turns out, the latest clinical trials on vitamins C and E and beta-carotene supplements didn't find that they protected against heart disease and cancer. In several studies, smokers in the group taking beta-carotene pills had a higher risk of lung cancer than smokers taking a placebo. Researchers at Johns Hopkins University conducted a meta-analysis (a research study that pools the results of the best-quality studies) to examine the effects of vitamin E supplements on the risk of death. The meta-analysis showed that people taking high doses of vitamin E (400 IU per day or more) had an increased risk of death (approximately 4 extra deaths for every 1000 people taking vitamin E at these doses). The researchers noted that most of the studies of high-dose vitamin E were done in people with chronic diseases, so it's unknown whether these results apply to healthy people.
There's still so much research going on to settle this question. Meanwhile, Mom was right - eat your fruits and veggies, because they're good for you!
