Q & A Library
What do you think of the new study showing that antioxidants don't cut the risk of heart disease and that beta-carotene may even increase the risk? I understand that the researchers recommended discontinuing clinical trials using beta-carotene supplements.
Answer (Published 7/14/2003)
In this report from the Cleveland Clinic Foundation, researchers analyzed data from 15 different studies of vitamin E and beta-carotene. Their conclusions and recommendations were published in the June 14th issue of The Lancet. The researchers concluded that use of beta-carotene and vitamin A supplements (a beta-carotene metabolite) should be discouraged, that clinical studies using these antioxidants should be discontinued, and that vitamin E should be excluded from trials of patients at high risk of coronary artery disease. These recommendations might appear alarming until you consider that the 15 studies analyzed took place among people already suffering from serious diseases or considered at high risk and that the results of the studies reviewed already were known.
Among the eight beta-carotene studies analyzed were two showing that the supplements didn't help prevent lung cancer among smokers. In fact, the harmful effects attributed to beta-carotene in the Cleveland Clinic analysis largely stemmed from these two studies, conducted among more than 43,000 smokers. In the seven vitamin E studies reviewed, the supplement reportedly didn't reduce the risk of stroke or of dying of heart disease among people who already were at high risk or ill.
Not surprisingly, the recommendations are controversial considering indications that vitamin E may still prove to help prevent heart disease among healthy people, and the lack of evidence showing that beta-carotene supplements are harmful to non-smokers.
The researchers also failed to consider the forms of carotenoids and vitamin E used in the studies they analyzed. I stopped recommending isolated beta-carotene supplements years ago and urge people to get the antioxidants they need from fruits and vegetables. Peaches, melons, mangoes, sweet potatoes, squash, pumpkins, tomatoes and dark leafy greens are good sources of beta-carotene and related carotenoids. If you want to supplement your diet, take a product that provides as many members of this family of protective pigments as possible: alpha-carotene, lutein, zeaxanthin, lycopene, etc. As for vitamin E, most studies use synthetic alpha-tocopherol. I recommend using natural vitamin E supplements that provide all four tocopherols and all four tocotrienols. Take 400 to 800 IUs of natural vitamin E daily, or 80 mg of tocopherols and tocotrienols. People under 40 should take 400 IUs a day; people over 40, 800 IUs.
Andrew Weil, M.D.
Dosage Update, October, 2004
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