Wednesday, June 15, 2011

Not getting older but wearing thin: the death of the anti-oxidant theory of aging

For 30 or 40 years we've been fed on a steady diet of claims that anti-oxidants were vital for reversing the oxidative damage to tissues that was widely taken to be the most important aspect of biological aging.  Eat your veggies and live forever (unless of course they are infected with E coli)!  Take your vitamin E and vitamin C!

There have been other theories of aging, but proponents have convinced NIH and other agencies that huge and expensive studies of anti-oxident dietary components and longevity, in humans and other animals.  How much disease and earlier-than-necessary death such lifestyle changes would occasion was never quite clear.  Advocates of the theory naturally wanted to say it was huge, or even most or all of what goes wrong in aging.  Anti-oxidants even protected against mutations, and hence cancer.

Well, a new paper in BioEssays by John Speakman and Colin Selman shows that the various kinds of evidence we now have suggests that antioxidants have little if any measurable effect on aging, and likewise the genes whose antioxidant (or equivalent) functions.

Given the statistical, institutionalized, miracle-promising funding and research landscape we have developed, this is actually not a surprising set of findings.  Debunking established ideas is rather commonplace (yet we still eat up the headlines proclaiming the next miracle).

Of course, we still age and die.  There are many reasons, and oxidative damage may be one of them.  Mutations are another.  Wear and tear is another.  Even telomere loss may be one!  For some reasons, most species have typical lifespans related to their body size or position in the phylogentetic tree of species.  Such findings fueled the belief, obviously correct in major ways, that genomic factors were responsible for aging patterns.  Many theories of how selection for lifespans--for 'death' would have operated.

Yet there have always been exceptions: species with lifespans far too long or short for their phylogenetic position.  And dietary reduction, telomeric experiments, and so on, have produced laboratory results that fueled these theories in one way or another.

But in real life, out here on the streets, things are somewhat different.  We know that moderation in all things (Hippocrates' recommendation around 400 BC) will lead to longer healthier life.  We also know of risk factors that affect only some causes of death or disease (smoking and lung cancer, for example), and that most people die of a disease, not of old age (the latter as a meaningful cause of death was pretty much given up decades ago).  Death, in real life, is timed by the assemblage of these various system-failures in the population, with particulars different for each individual.  Longevity and its net selective effects have probably always pertained, with no one cause evolving, or being necessary for the march of evolution.

Sorry, no miracle pills.

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