Are antioxidants as effective against cancer as believed?
antioxidants, marketed as cancer fighting agents, are not as effective as claimed by the pharmaceutical giants. As per an analysis, the companies are making profits by capitalising on a blind belief -- that antioxidants can counter cellular damage and cancerous gene mutation induced by the oxidation of cells.
Goran Bjelakovic and his colleagues from the Copenhagen University Hospital, Denmark, compared the efficacy of antioxidants -- b-carotene, vitamins a, c, e and selenium -- with that of placebos in preventing gastrointestinal cancers. Gastrointestinal tract is the key site of the antioxidant action.
The researchers analysed results of 14 worldwide clinical trials during which the effects of placebos and antioxidant supplements were assessed among healthy people and those with high risk of cancer (such as smokers and patients of oesophageal dysplasia {pre-cancerous stage}). The antioxidant supplements had been given to the subjects either separately or in combination for 1-12 years.
The result of the analysis was startling: consumption of b-carotene, vitamin a, c and e separately or in combination did not prevent the occurrence of gastrointestinal cancer. Rather, consumption of b-carotene in combination with vitamin a or e significantly increased mortality (when compared to placebos). Selenium was the only supplement that showed beneficial effects.
The findings should not be taken with a pinch of salt, for carotene is a widely consumed antioxidant. The researchers, however, warn their findings are only applicable to antioxidant supplements; the results could be contrary in case of antioxidant intake via fruits and vegetables. These foodstuffs contain safe levels of antioxidants. Most of the subjects of the trials had substantially higher antioxidant doses than what is found in balanced food. According to Bjelakovic, for every one million people exposed to 'toxic' amounts of antioxidant supplements, about 9,000 premature deaths occur.
The researchers hope their findings will serve as an eye-opener and doctors will no longer promote antioxidant pills to prevent or combat cancer.
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