It seems that often when a new study comes out, there are many who like to point their finger and say "see? that proves ---" as if one single study always definitively establishes or disproves the efficacy of a given chemical agent, be it vitamin or drug. Some people also think that the fact it appears in a prestigious journal like JAMA necessarily indicates it is gospel truth. Evidently, this recent study of vitamin E is rather crude. The following paragraphs quoted is from the June issue of Life Extension magazine, the full text of which can be found online at:
http://www.lef.org/magazine/mag2001/june2001_report_vitamine_01.html
The fact that vitamin E by itself failed to demonstrate suppression of lipid peroxidation is not surprising. It has long been known that vitamin E requires other antioxidants in order to recycle itself back into a free radical scavenger.(2-6) The people who participated in this study were screened to make sure that none of them had taken a multi-vitamin supplement in the preceding month. During the course of the study, the subjects were not allowed to take any supplement other than the prescribed vitamin E. This meant that there were no other antioxidants available to recycle vitamin E end-products back into effective suppressors of free radicals.Studies published many years ago showed that for vitamin E to function as a continuous antioxidant, ample levels of vitamin C must be present to regenerate (donate more electrons) to vitamin E in the body. The subjects who participated in the JAMA study were not allowed to take vitamin C or any other supplement that would have enabled the vitamin E to function as an effective antioxidant.
The critical importance of "gamma" tocopherol
In this JAMA study, the dose administered to the test subjects ranged from 400 IU to 2000 IU per day of the "alpha" tocopherol form of vitamin E. It has been established that consuming only alpha-tocopherol can lower blood levels of the more potent form of vitamin E called "gamma" tocopherol.
Scientists have shown that the average American's blood-stream is five times more rich in alpha-tocopherol than gamma-tocopherol and that difference jumps 20-fold among people who take alpha-tocopherol supplements. Since the alpha form of vitamin E displaces the critically important gamma-tocopherol, it is understandable why people given high doses of only alpha-tocopherol would not show a reduction in lipid peroxidation.(7)
The vitamin E capsules were oil-based. This was not disclosed in the JAMA article and Life Extension magazine had to call the researchers to discover this piece of information. The researcher¡¦s were unable to tell us what type of oil was used in the capsules, nor were they able to confirm if an antioxidant like ascorbyl palmitate was added to the capsules to protect the oil from oxidizing. Here is a quote from the description of these vitamin E supplements given to us by one of the scientists who authored the JAMA study:
"To the best of my knowledge it was oil-based. It was a amber colored capsule that contained a liquid preparation."
...unprotected oil-based alpha-tocopherol may turn rancid. While vitamin E functions as an antioxidant in the body, it does not adequately protect oil in capsules. The reason for this is that supplemental alpha-tocopherol is in an ester form and it does not become a good antioxidant until it is de-esterified in your body. Had the superior dry powder alpha-tocopherol been used, the outcome of this study may have been different.
There are a several methods to evaluate free radical activity in the body, yet the researchers who conducted this JAMA study chose to restrict their analysis to only urinary measurements. We would have preferred to see blood tests that would measure thiobarbituric acid-reactive substances, plasma lipid peroxides, malondialdehyde levels and conjugated diene formation. These blood measurements of oxidation are the gold standard by which antioxidant efficacy is measured in the body. Had these blood tests been used instead of urine tests, the results of this study may have shown some degree of protection against oxidation.
Ignoring the positive studies
As of press time, 92 studies that include vitamin E have been published in the year 2001. The vast majority of these studies showed health benefits in those who supplement with vitamin E. Out of all of these studies, the media chose to use this one JAMA report to unfairly attack the use of vitamin E supplements.
(added a couple pertinent paragraphs)