Related Resources • Antioxidants - bad for the heart?

By DrRich

In the June 14, 2003 issue of Lancet, a new analysis of previous large, randomized clinical trials conducted with beta-carotine and vitamin E show that the risk of total mortality, cardiovascular death, or stroke are not improved by these two antioxidant vitamins.  Indeed, while vitamin E merely failed to show a benefit, the incidence of total mortality and cardiovascular death was actually increased with beta-carotene.

The new analysis was a meta-analysis - a technique for summarizing the overall results of several clinical trials.  In the case of vitamin E, seven randomized clinical trials were included in the meta-analysis, each of which had enrolled over 1000 patients, for a total of over 81,000 patients studied.  Eight beta-carotene trials were analyzed, totaling more than 138,000 patients.

The researchers who conducted this meta-analysis point out that these results do not necessarily mean that the antioxidant theory (in which sufficient antioxidants might help prevent the progression of atherosclerotic heart disease) is false.  Instead, these results more likely reflect the fact that both vitamin E and beta-carotene, while described and sold as antioxidants, are in fact very weak antioxidants.

This is not the first time that studies with commonly-used antioxidants failed to show a benefit for preventing cardiac disease. (Click here for previously reported information on antioxidant vitamins.)   However, this is the first time the potential of beta-carotene to increase the risk of cardiovascular death has been identified in a large study.

Should people take antioxidant vitamins?

There seems to be little reason to do so, at least for the prevention of heart disease.  Future trials looking at new drugs that have a stronger antioxidant effect may show that true antioxidants are helpful - but right now we just don't have good evidence that available antioxidants offer much benefit.

In the case if vitamin E, at least the drug does not appear to be detrimental.  Further, studies are ongoing with vitamin E to examine suggestions that this vitamin may be helpful in preventing cancer.

However, the results with beta-carotene are disturbing, and unless one has specific instructions from a doctor to take this substance, supplements of beta-carotene should probably be avoided.