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But a controversial new review of data from 68 studies shows that some of the antioxidant supplements that people take to prevent or treat disease might actually increase their risk of all-cause mortality (death).
The study, published in the February 28 issue of the Journal of the American Medical Association, assessed the effects of these supplements in the general adult population as well as in patients with conditions such as heart, neurological, skin, renal, gastrointestinal and inflammatory disease.
The researchers came to the following conclusions:
- Better and urgent understanding of the mechanisms and actions of antioxidants in relation to disease and disease progression is needed.
- Singly, or in combination with other supplements, supplementation with beta-carotene increased mortality significantly.
- Vitamin A supplementation, in combination with other supplements, increased mortality significantly.
- Vitamin E, given on its own or in combination, significantly increased mortality.
- Vitamin C supplementation was not found to increase mortality or longevity.
- Selenium, given in combination or as a single supplement, was found to have no significant effect on mortality. It tended to have a protective effect, but more research is needed to confirm this effect.
- Beta-carotene, vitamin A and vitamin E, in single preparations or in different combinations, significantly increased mortality.
- This data is not relevant in populations with specific needs as well as confirmed deficiencies of antioxidants or other nutrients.
To supplement or not to supplement
These results will no doubt cause confusion among consumers, particularly among those who have been using vitamin/antioxidant supplementation.
Consumers who believe they need to take supplements should take the following advice from Prof Demetre Labadarios, director of the Nutrition Information Centre of the University of Stellenbosch (NICUS), to heart:
- Make sure you are consuming an adequate diet, which includes a variety of foods.
- Consult an expert on the adequacy of your diet.
- Avoid supplements with glamorous multi-claims, which cannot be substantiated when scrutinised.
- Avoid single-nutrient supplements.
- Check the composition of the supplement you plan to take or are taking.
- Choose a multi-vitamin, multi-mineral supplement that contains up to 2-3 times the recommended intake.
- Reassess your need to take such supplements regularly and for prolonged periods.
- Report to your doctor any adverse effects you think may be linked to the supplements.
For more information, visit www.sun.ac.za/nicus.
- (NICUS, Health24, March 2007)
