Why Calorie Restriction Diets Won't Increase Longevity in Humans

  •   #1  
    kiramira's Avatarkiramira , 07-22-2009 03:04 PM
    From http://www.ncbi.nlm.nih.gov/pubmed/16046282

    Caloric restriction (CR) extends maximum longevity and slows aging in mice, rats, and numerous non-mammalian taxa. The apparent generality of the longevity-increasing effects of CR has prompted speculation that similar results could be obtained in humans. Longevity, however, is not a trait that exists in a vacuum; it evolves as part of a life history and the physiological mechanisms that determine longevity are undoubtedly complex. Longevity is intertwined with reproduction and there is a cost to reproduction. The impact of this cost on longevity can be age-independent or age-dependent. Given the complexity of the physiology underlying reproductive costs and other mechanisms affecting life history, it is difficult to construct a simple model for the relationship between the particulars of the physiology involved and patterns of mortality. Consequently, we develop a hypothesis-neutral model describing the relationship between diet and longevity. Applying this general model to the special case of human longevity and diet indicates that the benefits of caloric restriction in humans would be quantitatively small.
    PMID: 16046282 [PubMed - indexed for MEDLINE

    Ageing Res Rev. 2005 Aug;4(3):339-50.


    Kira
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  •   #2  
    BoBoGuy's AvatarBoBoGuy , 07-22-2009 04:03 PM
    I agree.

    Many researchers however do believe the evidence to date shows the practice of CR will extend the human life span, but consensus has not yet been reached on this topic.

    Simply put, caloric restriction has not yet been proven to extend human lifespan!

    Bo
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  •   #3  
    mayness's Avatarmayness , 07-22-2009 05:06 PM
    Interesting. I read the whole paper out of curiosity. I may have skimmed some of the equations and graphs but I wasn't convinced that decreased reproduction (and, therefore, decreased cost of reproduction on lifespan) explained THAT MUCH of the longevity increase in the model organisms they talk about.

    I liked the below paragraph (bolding mine) -- I know they're not implying directly that CR would have an effect on cancer, but... well, now I want to go see what research has been done on that topic.
    Quote:
    By any accounting, rodent life histories clearly are characterized by greater reproductive effort. Laboratory caloric restriction studies, however, are comparisons of non-reproducing animals and yet the restricted animals still live longer than the controls. This suggests the complexity of the physiology involved and may be due to the fact that an important component of the cost of sustaining reproductive readiness in mammals is increased carcinogenesis associated with circulating reproductive hormones, particularly estrogen (see, e.g. Key and Pike, 1988 T.J.A. Key and M.C. Pike, The dose–effect relationship between “unopposed” oestrogens and endometrial mitotic rate: its central role in explaining and predicting endometrial cancer risk, Br. J. Cancer 57 (1988), pp. 205–212. View Record in Scopus | Cited By in Scopus (156)Key and Pike, 1988), progesterone (see, e.g. Pike et al., 1993), and testosterone (see, e.g. Guy and Auslander, 1973).
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