The other issue concerning supplements is there’s ambiguity about the correct dosage. Some doctors, for example, have suggested that cancer patients on a treatment designed to increase their free radicals may want to avoid antioxidants. "Correct dosage can be a problem with supplements because it's easy to exceed healthy amounts and set the normal balance off," Collins says . "On the other hand, supplements might turn out to be helpful if it is found that larger amounts of particular phytochemicals do produce benefits. For now, consuming the large amounts possible with some supplements is a risky gamble."
According to National Institutes of Health's National Center for Complementary and Alternative Medicine, "Large, long-term studies (randomized, controlled trials) funded primarily by NIH have generally found that antioxidant supplements have no beneficial effects."
Can taking supplements ever be harmful?
Janet Brill, Ph.D., R.D., a Florida-based nutrition expert, thousands of studies have examined the effects of antioxidant supplements such as vitamin E, beta carotene and vitamin C on chronic diseases.
"While most have shown either beneficial or neutral effects, there is some concern over research demonstrating that higher doses can actually increase myocardial events and promote cancer cell proliferation." For example, The Beta-Carotene and Retinol Efficacy Trial, which looked at more than 18,000 men and women who were smokers, former smokers or workers exposed to asbestos, found that after four years lung cancer incidence was 28 percent higher in those taking beta carotene supplements compared with those taking a placebo.
The Cochrane Library, a well-known scientific research collaboration, reviewed 67 trials with a combined 232,550 subjects to assess the effects of antioxidant supplements on mortality and concluded that there is "no evidence to support antioxidant supplements for primary or secondary prevention" of mortality. And, in fact, vitamin A, beta carotene and vitamin E may increase mortality. This review was controversial and disputed by supplement manufacturers and food manufacturers that add supplements to foods.
I've seen the term ORAC associated with antioxidants - what does that stand for?
Oxygen radical absorbance capacity. It is one method used to measure the amounts of antioxidants in foods. Here is the United States Department of Agriculture's ORAC
for selected foods.
Where to you get the most antioxidant bang for your buck?
While we know that many vegetables and fruits are high in antioxidants, we don’t have as much evidence to determine specific amounts in each food. Collins points out that we need to think about foods differently from the way we have in the past — not in terms of rank but of synergistic combinations. "In the old days we seemed to consider certain foods high in particular vitamins ‘better’ than others; today we know that even when a fruit or vegetable is not a major source of vitamin C or A or antioxidants, for example, it can supply important phytochemicals that improve your overall health." And while fruits and vegetables are good sources, antioxidants are also found in nuts, seeds, legumes, coffee, tea and chocolate.