Saturday, October 20, 2012

Another Reason to Exercise!

I have not blogged before on health and fitness issues, but the subject does interest me.

Some interesting news this year on why exercise has positive health effects:
“Exercise and Longevity,” The Economist, 21 January, 2012.

Gretchen Reynolds, “Exercise as Housecleaning for the Body,” New York Times Blogs, 1 February, 2012.
These news stories report the findings of the following paper:
Congcong He, Michael C. Bassik, Viviana Moresi, Kai Sun, et al. 2012. “Exercise-induced BCL2-regulated autophagy is required for muscle glucose homeostasis,” Nature 481: 511–515 (26 January).
The upshot of this research is that exercise promotes autophagy (which comes in three kinds: macroautophagy, microautophagy and chaperon-mediated autophagy), the intracellular process by which bad proteins and other cellular waste are broken down and removed from the cells.

Vigorous up-regulated autophagy appears to help you ward off diseases like cancer, neurodegenerative disorders, infections, inflammatory diseases, and insulin resistance. So now the mechanism by which exercise increases human health – autophagy – seems to be better understood.

But the most interesting aspect of this research relates to autophagy and the way that human beings age: there is some evidence that increased autophagy not only increases one’s health but also one’s life expectancy. It is claimed by some that increased (or up-regulated) autophagy might slow aging in humans, and one can read further about this subject here:
Eric Drexler, “Autophagy: Why you should eat yourself,” Eric Drexler's Blog: MetaModern, 24 July, 2010.

Eric Drexler, “Trehalose, autophagy, and brain repair: Sweet,” Eric Drexler’s Blog: MetaModern, 15 September.
I suspect skepticism is in order. For one thing, a lot of the discussion of this issue seems to mix up human life span with life expectancy. They are not the same thing. Life span is the maximum extent to which an organism can live. The age of 120 seems to be about the upper limit of human life span,* and people very rarely ever live that long. But life expectancy is how long on average the organisms of a species actually live, or how long any one organism might be expected to live. Life expectancy in the US is 78.2 years.

Whatever benefits one can get from up-regulated autophagy (assuming one has a healthy diet and life style too!) would appear to increase one’s life expectancy, not human life span. And drugs that slow down or reverse aging are still the stuff of science fiction.

Another interesting theory emerging in current research is that antioxidants block autophagy, as reported here:
Eric Drexler, “Antioxidants block cell repair —New information and what it may mean,” Eric Drexler’s Blog: MetaModern, 26 September, 2010.
Amongst health conscious people there appears to have arisen a fad in recent years that one should take antioxidant supplements such as vitamin C, vitamin E, grape seed extract, etc.

But now it seems that the alleged health benefits of such supplementation are overrated – and perhaps even harmful, in that mega-dosing with antioxidants might block the health benefits that people normally get from exercise-induced autophagy.

Caloric restriction (cutting down one’s amount of food consumed while maintaining optimum nutrition) is also supposed to up-regulate autophagy. Some reasonably credible research has found that certain supplements like resveratrol increase the lifespan (or should that be life expectancy?) of organisms like yeast, fruitflies and nematode worms, but as far I can see there is no convincing scientific evidence for the same effect in humans (needless to say: what works in nematode worms or flies does not necessarily work in humans!).

* The oldest documented human being was apparently Jeanne Louise Calment (1875–1997) who died at the age of 122 years and 164 days!

N.B.: I don’t offer people health advice on this blog, nor are my comments above meant to be actual health advice for readers!

Update: Another supplement that supposedly induces autophagy is pterostilbene, but I have not seen enough good sources on this yet.