One of the most robust interventions for life-extension known to us is dietary restriction (DR), usually defined as a 20-40% reduction of ingested calories compared to the ad-libitum fed scenario. DR has been shown to work in organisms ranging from yeast to rodents and is central to longevity research.
However, DR studies performed on non-human primates were rather disappointing, casting doubt whether this finding would be ever translatable to humans. Prof. Thomas Kirkwood, a well known gerontologist, pointed this out at the recently held FENS 2015 Nutrition Conference in Berlin. He argued that DR likely redistributes our body's ressources by shutting down reproductive functions in favour of somatic maintenance. If this is true, then certainly, DR would loose its attractiveness to most of its present proponents.
In addition, Prof. Kirkwood highlighted findings from a 2009 paper published by Liao et al. in the journal Aging Cell that the life-extending property of DR is not even universal within one species, namely that of laboratory inbred mice. Of the 41 strains (of both sexes) tested, only 5% of male mice strains and 21% of female mice strains showed a significant lifespan extension. Contrarily, DR shortened lifespan in approximately one fourth of all male and female strains! Their findings render DR's applicability to humans questionable, to say the least. On a more positive note, the comparison of different strains of a species upon the same treatment or intervention is a very interesting tool to delineate the genetic drivers between responsiveness and biological inertia. In fact, longevity related genes were identified as a result of this approach, advancing longevity research further, albeit unexpectedly.
However, DR studies performed on non-human primates were rather disappointing, casting doubt whether this finding would be ever translatable to humans. Prof. Thomas Kirkwood, a well known gerontologist, pointed this out at the recently held FENS 2015 Nutrition Conference in Berlin. He argued that DR likely redistributes our body's ressources by shutting down reproductive functions in favour of somatic maintenance. If this is true, then certainly, DR would loose its attractiveness to most of its present proponents.
In addition, Prof. Kirkwood highlighted findings from a 2009 paper published by Liao et al. in the journal Aging Cell that the life-extending property of DR is not even universal within one species, namely that of laboratory inbred mice. Of the 41 strains (of both sexes) tested, only 5% of male mice strains and 21% of female mice strains showed a significant lifespan extension. Contrarily, DR shortened lifespan in approximately one fourth of all male and female strains! Their findings render DR's applicability to humans questionable, to say the least. On a more positive note, the comparison of different strains of a species upon the same treatment or intervention is a very interesting tool to delineate the genetic drivers between responsiveness and biological inertia. In fact, longevity related genes were identified as a result of this approach, advancing longevity research further, albeit unexpectedly.
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| Strain variation in mean lifespan of ILSXISS recombinant inbred (RI) mice under ad libitum
(AL) and dietary restriction (DR) diets. Lifespans were typically
obtained from 10 AL and 10 DR mice from each strain (5 males & 5
females per treatment group).The mean lifespans in the upper two panels are shown for each strain
[AL (□) and DR (■)], ranked in ascending order according to the AL means
(A: males, 41 strains; B: females, 39 strains). The lower two panels
illustrate the deviation (positive and negative) of the mean DR lifespan
from the mean AL for the same strains, ranked from the strain with the
greatest increase in lifespan under DR to the strain with the greatest
decrease (C: males; D: females). Error bars represent SEM. * p < 0.05, ** p < 0.01, *** p < 0.001 by t-test (no experiment-wise Bonferroni correction). [from publication] |
Liao, C.-Y., Rikke, B. A., Johnson, T. E., Diaz, V. and Nelson, J. F. (2010), Genetic variation in the murine lifespan response to dietary restriction: from life extension to life shortening. Aging Cell, 9: 92–95. doi: 10.1111/j.1474-9726.2009.00533.x
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