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advertisement On November 10, 2004 CNN and other news agencies released reports on the potential risks of taking Vitamin E. These reports stemmed from a recently released report (pre publication) from the Annals of Internal Medicine, a peer review medical journal. The article (to come out in a January 2005 issue) was a meta-analysis of high dose vitamin E supplementation that may increase mortality. The investigators were Drs. Miller, Pastor-Barriuso, Dalal, et. al. Dr. Edgar Miller of Johns Hopkins University in Baltimore, who led the study, stated “It's about a 5-percent increased risk at 45 years in the trials pooled together for increased death by all causes.” Problems with this study are many. As a consequence of such problems it would be illogical and irresponsible for me to recommend discontinuation of vitamin E supplementation to my patients based on this single study. Let’s take a look at the study design and what was actually examined. Firstly, a meta-analysis is not a double-blinded-placebo-controlled study designed for the sole purpose of determining the answer to the question “Does Vitamin E supplementation cause increased risk of death?”; rather it analyses a mix of previously published studies investigating different questions or problems. It is not the best method to examine a cause and effect relationship between vitamin E supplementation and increased risk of death. Secondly, the authors of this meta-analysis sampled published studies from 1993 until 2004 in which vitamin E was supplemented with varying doses from as low as 16.5 International Units (IU) to as high as 2000 IU per day. Only nine of the 19 studies analyzed used vitamin E alone, with the majority using other dietary supplements in combination with vitamin E. Also of paramount importance was the type of vitamin E used. It appears that the only vitamin E used was the single isomer alpha-tocopherol and none contained other tocopherol or tocotrienol isomers found in the vitamin E family and found in natural (mixed) vitamin E. It is the recommendation of this doctor that only natural (preferably mixed) tocopherols (d-alpha-tocopherol, etc.) be used for supplementation. The synthetics while less expensive and more prevalent in the market place have never been shown to be equal to that occurring in nature. Since the biochemistry of alpha and non-alpha isomers is significant, one can only guess what the importance this may play on study outcomes. This is a true confounding factor not to be underestimated. Thirdly, if we look at the population of subjects picked for those 19 studies we see that the subjects were generally not healthy, or had significant risk for developing diseases being studied in the respective studies. This is not a good sampling of the “general population”. It may not be appropriate to make generalizations from these subjects to the population at large. Fourthly, if we look at the numerous clinical studies thus far that studied vitamin E supplementation we can be comforted to know that it appears quite a safe supplement to take. Levels as high as 1600 IU per day are deemed safe by the Institute of Medicine. And the Linus Pauling Institute at Oregon State University, they are comfortable in recommending a dose of 400 IU/day with the statement that “there is no convincing evidence that vitamin E supplementation up to 800 IU/day increases the risk of death from cardiovascular disease or other causes.” In conclusion, this single meta-analysis cannot support a movement to change the current value of vitamin E supplementation or further recommend its discontinuation. I will continue to recommend between 200 and 400 IU per day of natural vitamin E supplementation. At least until such time as convincing well-designed analysis of the questions of risk dictates otherwise. JP Saleeby, MD is assistant medical director of the Emergency Department at LRMC in Hinesville, GA. He also has an interest in nutritional and preventive medicine. Dr. Saleeby can be reached for comment at jpsaleeby @ aol.com |
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