GRIM
05-09-2008, 10:36 AM
http://www.ucsf.edu/synapse/articles/2008/May/8/antioxidants.html
By Darya Pino
Science Editor
For the past several years, antioxidants have been considered by many to be a veritable cure-all for health ailments from the common cold to cancer. The idea was that these chemicals can protect cells in the body from damaging particles known as free radicals, so a huge movement began to pack antioxidants into as many products as possible.
Today supplements with mega doses of antioxidants are readily available over the counter, but a recent review of scientific literature warns us that loading up on vitamins and oxidants does not protect against overall mortality and may actually be harmful when taken in high doses.
The review was published in the Cochrane database on April 16.
Researchers performed a systematic review of 67 randomized clinical trials (232,550 participants) where antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) were compared to placebo or no intervention. Participants were either healthy individuals or diagnosed with a specific disease.
Antioxidant supplementation did not reduce mortality risk overall, but beta-carotene, vitamin A and vitamin E significantly increased the risk when taken at high doses. The authors recommend more research be conducted on the effects of vitamin C and selenium, though currently no harm or benefit was shown.
Importantly, this study only analyzed the effects of antioxidant supplements, not antioxidants obtained from fruit and vegetables. In fact, a major reason antioxidants were thought to be beneficial in the first place is because of observational studies showing reduced risk of chronic diseases with a higher intake of fruits and vegetables. Since these foods are high in antioxidants, these compounds were suspected to be the key component for disease prevention. However, it appears that antioxidants alone are not able to reduce mortality and may actually be harmful in higher doses.
Despite this it may still be true that antioxidants are involved in disease prevention, but only in the context of the whole food or some combination of elements in the food. So far, attempts to isolate a single ingredient from food has not been able to replicate the beneficial effects of an overall healthy diet.
By Darya Pino
Science Editor
For the past several years, antioxidants have been considered by many to be a veritable cure-all for health ailments from the common cold to cancer. The idea was that these chemicals can protect cells in the body from damaging particles known as free radicals, so a huge movement began to pack antioxidants into as many products as possible.
Today supplements with mega doses of antioxidants are readily available over the counter, but a recent review of scientific literature warns us that loading up on vitamins and oxidants does not protect against overall mortality and may actually be harmful when taken in high doses.
The review was published in the Cochrane database on April 16.
Researchers performed a systematic review of 67 randomized clinical trials (232,550 participants) where antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) were compared to placebo or no intervention. Participants were either healthy individuals or diagnosed with a specific disease.
Antioxidant supplementation did not reduce mortality risk overall, but beta-carotene, vitamin A and vitamin E significantly increased the risk when taken at high doses. The authors recommend more research be conducted on the effects of vitamin C and selenium, though currently no harm or benefit was shown.
Importantly, this study only analyzed the effects of antioxidant supplements, not antioxidants obtained from fruit and vegetables. In fact, a major reason antioxidants were thought to be beneficial in the first place is because of observational studies showing reduced risk of chronic diseases with a higher intake of fruits and vegetables. Since these foods are high in antioxidants, these compounds were suspected to be the key component for disease prevention. However, it appears that antioxidants alone are not able to reduce mortality and may actually be harmful in higher doses.
Despite this it may still be true that antioxidants are involved in disease prevention, but only in the context of the whole food or some combination of elements in the food. So far, attempts to isolate a single ingredient from food has not been able to replicate the beneficial effects of an overall healthy diet.