Cautious Studies Tend to Disprove Dietary Longevity Claims
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A research group is presently working through a grand tour of replicating longevity claims in mice, using careful and cautious study designs that eliminate calorie restriction effects as much as is possible. This sort of approach shows that many past claims of dietary additions that modestly extend life in mice were probably the result of inadvertent calorie restriction - which is why you have to look carefully at every study to make sure that researchers controlled for this issue. Calorie restriction has a comparatively large effect on life span in smaller animals, such that even mild restriction can swamp all other contributions to life span that occur in a study:

Phytonutrients reportedly extend the lifespan of C. elegans, Drosophila, and mice. We tested extracts of blueberry, pomegranate, green and black tea, cinnamon, sesame, and French maritime pine bark (Pycnogenol and taxifolin), as well as curcumin, morin, and quercetin for their effects on the lifespan of mice. While many of these phytonutrients reportedly extend the lifespan of model organisms, we found no significant effect on the lifespan of male, F1 hybrid mice, even though the dosages used reportedly produce defined therapeutic endpoints in mice.

The compounds were fed beginning at 12 months of age. The control and treatment groups were isocaloric with respect to one another. A 40% calorically restricted and other groups not reported here did experience lifespan extension. Body weights were unchanged relative to controls for all but two supplemented groups, indicating most supplements did not change energy absorption or utilization.

Published reports of murine lifespan extension using curcumin or tea components may have resulted from induced caloric restriction. Together, our results do not support the idea that phytonutrient-antioxidants and anti-inflammatories are potential longevity therapeutics, even though consumption of whole fruits and vegetables is associated with enhanced health- and lifespan.

Link: http://www.ncbi.nlm.nih.gov/pubmed/23432089

Comments

At first glance a depressing result. On reflection, cause for optimism as there seems to be one and only one way to increase lifespan: calorie restriction. And it doesn't seem to matter how you do it.

Assuming the results are repeatable and turn out to be true.

Posted by: Steve Morris at February 27, 2013 9:24 AM

@Steve Morris: Calorie restriction effect size for lifespan is probably very small in humans. There are both a priori logical and empirical reasons for believing this.

There is in fact one and only one way to meaningfully increase human lifespan, and that is to get over the oral fetish and advance biomedical research into rejuvenation biotechnologies. Anything else will be absolutely unavailing.

Posted by: José at February 27, 2013 3:35 PM
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