SAGE KE Bulletin Board
8 July 2002
You make a good point. One problem with all of these types of studies is that there are tons of confounding factors that make interpretation of any results (particularly negative results) difficult. How well did the subjects really keep to the regimen? What about dosage? What about other things present in the particular food/juice/extract that may interfere with any beneficial effects? Were the patients monitored for a long enough period of time? Was the sample size large enough? In the case where data is collected based on a subject's memory, how accurate is their recollection? Of course, these are just a few of the potential problems.
There are a couple of papers just out in JAMA that suggest a possible link between dietary intake of vitamins E and C and reduced risk of Alzheimer disease. These studies suffer from many of the problems I outlined above, but in my opinion, are still of interest. One particularly interesting feature of these articles is that they claim the benefits of vitamins E and C are only obtained from dietary sources and not from supplements.
In any case, I would say the jury is still out on the benefits of high doses of antioxidants in combating aging and diseases of old age. My guess is that some antioxidants (vitamin E in particular) will have very beneficial effects when taken in the right dosage and with the right combination of other vitamins and nutrients. Of course, there will likely be genotype specific effects as well that will need to be considered. For now, we obviously don't know enough about how these antioxidants work and interact with other molecules inside the human body to design effective antioxidant regimens with any degree of certainty.
One point that I don't think receives enough attention in these types of discussions is the potential negative effects of some antioxidants. For example, a reduction in CoQ apparently results in a longer life span in C. elegans. Yet, many people take CoQ supplements and CoQ has been marketed as an anti-aging compound. Is it possible that people are really shortening their lives by taking extra CoQ? Another example are the EUK drugs that extend life span in C. elegans but shorten life span in Drosophila. Which effect would they have if given to humans? The answer is that we really don't know. Until accurate measures for aging and rates of aging are developed, we will really never know whether "anti-aging" compounds are having their desired effect.
Engelhart, M. J., Geerlings, M. I., Ruitenberg, A., van Swieten, J. C., Hofman, A., Witteman, J. C., and Breteler, M. M.(2002). Dietary intake of antioxidants and risk of Alzheimer disease. Jama 287, 3223-9.
Morris, M. C., Evans, D. A., Bienias, J. L., Tangney, C. C., Bennett, D. A., Aggarwal, N., Wilson, R. S., and Scherr, P. A.(2002). Dietary intake of antioxidant nutrients and the risk of incident Alzheimer disease in a biracial community study.JAMA 287, 3230-7.
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