X-Message-Number: 12292
Date: Fri, 20 Aug 1999 08:43:21 -0700 (PDT)
From: Doug Skrecky <>
Subject: null effect of caloric restriction in aged rats

  Lipman RD.  Smith DE.  Blumberg JB.  Bronson RT.
  Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University,
  Boston, Massachusetts 02111, USA.
  Effects of caloric
  restriction or augmentation in adult rats: longevity and
  lesion biomarkers of aging.
  Aging (Milano).  10(6):463-70, 1998 Dec.
  Caloric restriction (CR) initiated in young
  rodents has been thoroughly documented to enhance longevity, but its efficacy
  when introduced at older ages has not been well investigated. Cohorts of 18-
  and 26-month-old male F344 x BN F1 hybrid rats were fed either: 1) NIH-31
  meal (C); 2) vitamin and mineral fortified NIH-31 meal (R); or 3) vitamin and
  mineral fortified NIH-31 meal supplemented with corn oil and sweetened
  condensed milk (S). The C control rats were fed ad libitum, R rats were
  restricted to 32% of the caloric intake of the controls, and
  S rats were allowed to consume not more than 8% more calories than C rats.
  After 6 weeks, the average weights were significantly different between all
  diet and age groups. Although calorie manipulation altered body weight, no
  significant effect of the dietary intervention on longevity was found. The
  average lesion burden, including tumor burden and prevalence of nearly all
  commonly occurring lesions, were comparable between the groups. Thus, the
  manipulation of weight at ages beyond middle age has a much less profound
  impact than similar interventions during growth and maturation in rats.

  Additional note by poster:

     This may have some relevance for humans as well. The scientific 
  evidence does not support any significant direct effect of caloric
  intake on mortality of healthy adult humans.

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