From: Alex Schauss [mailto:alex@
Sent: Wednesday, February 28, 2007 4:26 PM
I was asked to send you some information on the
I have been informed by a physician in Europe that the senior author, Dr. Goran Bjelakovic is working at the Copenhagen Trial Unit in
Aliment Pharmacol Ther. 2006
Conclusion: We found no convincing evidence that antioxidant supplements have
significant beneficial effect on primary or secondary prevention of
Cochrane Database Syst Rev. 2004 Oct 18;(4):CD004183
REVIEWERS' CONCLUSIONS: We could not find evidence that antioxidant
supplements prevent gastrointestinal cancers. On the contrary, they
seem to increase overall mortality. The potential cancer preventive
effect of selenium should be studied in adequately conducted
Lancet. 2004 Oct 2-8;364(9441)
INTERPRETATION: We could not find evidence that antioxidant
supplements can prevent gastrointestinal cancers; on the contrary,
they seem to increase overall mortality. The potential preventive
effect of selenium should be studied in adequate randomised trials.
The range of doses in the different trials they selected for the meta-analysis is dramatic. For example, vitamin A ranged from 1333 IU to 200,000 IU, and vitamin E from 10 IU to 1000 IU. The duration of the studies range from 28 days to 12 years. Nevertheless they were all lumped together.
The most serious violation of this study is the endpoint – mortality. In none of the studies they selected for the meta-analysis was mortality the endpoint.
I have to question their blood data. The authors decided that a vitamin C level of >46 µmol/L was high and >32 µmol/L low. This doesn’t agree with data that shows blood levels above 80 µmol/L occurring in individuals eating a diet rich in fruits and vegetables. Vitamin C supplementation can easily increase blood levels several fold above this amount before bowel toleration might occur. This has to raise questions about compliance.
The issue of compliance is of concern. Information is lacking in the study on subject compliance. Without information on blood levels and pill counts for each subject one can not have confidence that the subject’s consumed the supplements in question. We don’t even have data from this
Because the authors decided to mix studies of different duration, dose, and route of administration, I think it is fair to agree with several colleagues who have concluded that by mixing all various studies together, They are not comparing apples and organ
Alexander Schauss, Phd, FACN
Dr. Schauss followed up his comments with a note to me that said, "By the way, the JAMA authors excluded two major large studies that showed antioxidants lower mortality and have health benefits. Had they included those in their meta-analysis the results would have shown they extended lifespan. I wonder why those studies were not included? Would JAMA have published those results?"