Antioxidants: useful supplements or should we refrain?

On June 16, LRG Science Team member, Omer Mercier passed away. We could think of no better tribute to him than reprinting an article he wrote for the LRG website.

Under different forms, antioxidants are in wide use among health-conscious people and even more so among cancer patients. They take the form of such dietary supplements as Vitamin C, E and A, beta-carotene, lycopene, selenium, ginger (Zingiber officinale), cucurmin (turmeric), or pomegranate juice.
Occasional controversies have been raised concerning their use, on grounds of serious or sometimes questionable arguments. Another controversy was raised lately, whereby the authors warned that several antioxidants could block therapeutic actions of some anti-cancer drugs, among them Gleevec (imatinib), thus suggesting they should not be used.
Today, we are facing total confusion on this topic; should we refrain from taking antioxidants? All of them or just some of them?
Our objective is to present a review of pertinent publications on biological actions of antioxidants, with particular emphasis on cancer patients. It does not focus on novel research results but rather attempts to sort out favorable and unfavorable arguments buried in existing publications, making it easier for GIST patients, and other cancer patients as well, to make decisions while understanding the issues at stake.

Antioxidants: many names and many sources

"An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by being oxidized themselves. Although oxidation reactions are crucial for life [e.g. respiration], they can also be damaging; hence, plants and animal maintain complex systems of multiple types of antioxidants as well as enzymes.

You can read the full article here.