Vitamin E study simply bad science
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To "E" or not to "E"?
The problem with the study on vitamin E is that it is simply not good science.
The study was a meta-analysis -- a statistical technique where researchers combine data from all the available clinical trials on a single issue, to give us an overview of whether something is helpful or harmful.
A good meta-analysis is a useful tool. It can help put apparently contradictory studies into perspective, and allow doctors to provide their patients with an overview of the effectiveness or ineffectiveness of treatments. In an era of information overload, where thousands of new medical papers are published every day, such summary papers reduce the amount of reading necessary to keep abreast of new developments.
But a major problem with this approach is that a good meta-analysis of badly designed studies still results in bad statistics. Statisticians have a saying for this: "Garbage in equals garbage out." In the case of this study, the "garbage" involved failure to make sure that all the clinical trials analyzed in the same meta-analysis used the same form of vitamin E.
There are two forms of vitamin E: the natural form found in food, and synthetic vitamin E, manufactured in the laboratory. Some synthetic vitamins are identical to their natural counterparts; but this is not true of vitamin E. In nature, vitamin E occurs as eight related chemical compounds � the tocopherols (alpha, beta, delta and gamma) and the tocotrienols (alpha, beta, delta and gamma). All of these are present in food or natural supplements. However, synthetic vitamin E contains only alpha-tocopherol.
Although there is not complete agreement between researchers, many studies now suggest that gamma-tocopherol, not alpha-tocopherol, provides superior protection against cancer and heart disease.
Moreover, experiments in humans and animals have shown that giving alpha-tocopherol alone, as happens when synthetic vitamin E supplements are given, can block absorption of gamma-tocopherol. There are therefore good theoretical reasons to be wary of taking synthetic vitamin E.
It is interesting to note that natural vitamin E is the only form available in health food stores. Drug stores do carry the synthetic form, but even there, most bottles of vitamin E on the shelves are natural. Natural vitamin E is therefore the form that the public generally uses. Only in some of the large-scale clinical trials do we see synthetic vitamin E regularly used.
Over half a century ago the Shute brothers � medical doctors in Ontario � pioneered the use of vitamin E for the treatment of heart disease-related conditions, such as intermittent claudication, angina, thrombophlebitis and the prevention of and recovery from heart attacks. Suspecting that synthetic vitamin E, first synthesized in 1938, might not have the same benefits as natural or food form, they used vitamin E prepared from wheat germ oil.
You might ask why synthetic vitamin E is still used in clinical trials, when there have been questions raised about its efficacy and safety for several decades? It's hard to say. Maybe it is because it's cheaper. Or perhaps because most of the studies using it were piggy-backed onto drug trials � one in a trial of statin drugs in heart patients, and the other of Hormone Replacement Therapy (HRT) in post-menopausal women � and the drug companies who make the synthetic form may have donated it.
You might also ask why the researchers who produced these latest meta-analyses failed to separate out studies using the different forms of vitamin E before doing their analysis. After all, the first rule of science is to eliminate all possible sources of bias. If a detrimental effect was seen only with synthetic vitamin E, then lumping together studies using synthetic and natural vitamin E introduces a source of error.
The challenge to the researchers now is recognize that the form of vitamin E used in different clinical trials is a confounding variable, and to repeat their analyses, this time, clearly distinguishing between the different forms.
The only way we will know for sure if there are risks attached to taking vitamin E supplements is to evaluate the safety of natural and synthetic supplements separately. After all, if synthetic vitamin E has a detrimental effect, as has been suspected for some time, we need to know.
Aileen Burford-Mason is an immunologist and nutritional consultant in Toronto
J Watkin
Biomedica Laboratories Inc.
The Nutraceutical Medicine Company Inc. (NMC)
250-746-9397
