X-Message-Number: 8629
Date: Fri, 26 Sep 1997 11:43:49 -0700 (PDT)
From: Doug Skrecky <>
Subject: Glycemic Index & longevity 

    From a health standpoint low GI foods win the day, because of their
 beneficial effect on insulin sensitivity. In Wistar rats for example
 insulin resistance develops after just 8 weeks of glucose feeding, at 16
 weeks of amylopectin starch feeding and after 26 weeks with a diet of 60%
 amylose/40% amylopectin. (Journal of Nutrition 126: 596-602 1996) The
 only factor that I am aware of that could account for these results, is
 differences in GI of glucose, and the glucose polymers amylopectin, and
 amylose starch. Even more interesting is the fact that increaseing GI by
 adding 20% glucose to chow shortens both mean and maximum life span of
 mice. (Mechanisms of Ageing and Development 92: 43-51 1996) This effect
 of insulin sensitivity on life span is further born out with the dramatic
 effect of high dose chromium picolinate on the life span of Long Evans
 rats. This increased to 44 months with chromium picolinate
 supplementation, which is record for this strain. This significantly
 exceeds the 36 months that is obtained for Long Evans rats that have been
 severely calorically restricted. Control rats live 29 months. (Medical
 Hypotheses 43: 253-265 1994 & J. Appl. Physiol. 70(4): 1529-1535 1991) I
 am in the process of developing a longevity database for this strain of
 rat.
    It is also interesting that Fisher 344 rats fed a low fat high complex
 carbohydrate diet do not develop the insulin resistance that rats fed a
 high fat, sucrose diet suffer from. (Gerontology 41: 205-211 1995) Also a
 low fat sucrose diet accelerates the rate of aging and decreases both
 mean, and maximum life span in Fisher rats. (Journal of Gerontology
 50A(3): B148-154) However I should mention that it might be the fructose,
 rather the GI that was the driving force here.
   It would be very interesting to test the effect of the same isocaloric
 diet provided in both a low and high GI form, on the rate of aging of
 rodents. The chow could contain either whole grains, for the low GI diet,
 or the same grains ground to a flour for the high GI diet. To my
 knowledge this experiment has never been performed. It would be an
 elegant and conclusive test for the effect of GI on life span, since
 there would exist no other explanation for any differences in life span.

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