Mittwoch, 18. März 2015

Don't judge the primate studies of Calorie Restriction if you haven't read them!

I despair when non-expert scientists and intelligent lay people unknowingly spread misinformation about calorie restriction (CR). Not long ago I had to read again that the primate studies somehow refute CR. The reality, however, is more nuanced than that. Do not forget: misinformation can jeopardize public understanding and acceptance of research.

I will echo Ingram and Roth on this topic and use this post as a future reference. Both were involved (principal investigators, I believe) with the CR primate studies. (emphasis mine)
The long-term study of rhesus monkeys at the University of Wisconsin reported significantly reduced morbidity and mortality in those monkeys maintained on 30% CR from adult ages (7–14 years of age) compared to controls (Colman et al., 2009 and Colman et al., 2014). In contrast, a report from the long-term study of rhesus monkeys from the NIA that we initiated in 1987 found no evidence of improved survival in monkeys initiated on 30% CR from young ages (2–6 years) or older ages (14–21 years) (Mattison et al., 2012). Differences in the design of these studies, particularly the dietary composition, are now being investigated to uncover reasons for the different outcomes. Even if the conclusion is ultimately that CR does not significantly extend lifespan in rhesus monkeys, there is ample evidence from these studies to demonstrate improved health and function at older ages in monkeys on CR. 
Better yet not judge any of data, if your understanding comes only from popular science articles. I welcome comments by everyone, including lay people, as long as they are informed. I'll briefly mention another controversy for the sake of completeness:

Addendum: Does CR work in wild-derived or heterogenous mice?
This is important since these mice are more representative of healthy animals than, say, gluttonous black 6 mice. As in primates, I think the preponderance of evidence says "yes". A recent paper on the "yes"-side of the equation includes a review of other studies as well (2). This includes the negative study by Liao, Rikke et al. and Harper et al. with wild-derived mice.

1. Ageing Res Rev. 2015 Mar;20C:46-62. doi: 10.1016/j.arr.2014.11.005. Epub 2014 Dec 19.
Calorie restriction mimetics: Can you have your cake and eat it, too?
Ingram DK, Roth GS.

2. J Gerontol A Biol Sci Med Sci. 2010 Dec;65(12):1275-84. doi: 10.1093/gerona/glq155. Epub 2010 Sep 5.
Life extension by diet restriction and N-acetyl-L-cysteine in genetically heterogeneous mice.
Flurkey K1, Astle CM, Harrison DE.

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