Re: Caloric Restriction Does not Slow Aging in Humans

Michael M. Butler (butler@comp*
Tue, 24 Feb 1998 23:34:59 -0800

The data and hypotheses as you state them only say that CR qua CR doesn't
No reputable CRAN proponent leaves out the AN (adequate/optimum nutrition)
Show me human work that controls for the presence or absence of AN throughout
the life of the subject, and I may be willing to concede the study has some
applicability. As it stands, all you're saying is that starvation doesn't

Well, duh.

FWIW, my BMI is way higher than I want it to be. I'll chance the
possibility that
CRAN may make my life (including exercise) more fun, even if it doesn't
extend it.


At 12:14 AM 2/24/98 -0800, you wrote:
> There has been some speculation that caloric restriction might be able
> to retard the rate of aging, and extend maximum human life span beyond
> 120 years of age. (For example see the book "The 120 Year Diet" by Roy
> Walford)
> Recent evidence indicates that the anti-aging effect of caloric
> restriction, which has been documented in rodents, is not operative in
> humans.
> A low body-mass index does have a positive association with reduced
> mortality rates in humans. However recent research indicates that this is
> due to a negative association between BMI and physical fitness. After
> physical fitness is accounted for, there exists no further effect of BMI
> on mortality. See the following table from (International Journal of
> Obesity 19 Suppl: S41-S44 1995.
> All Cause Death Rates
> BMI Fitness
> Low Moderate High
> <27 52.1 28.6 20.0
> 27-30 49.1 29.8 19.7
> >30 62.1 18.0 (moderate & high together)
> While the above data indicate that the body mass index itself is not
> a primary driving factor for mortality in humans, the case it makes
> against caloric restriction exerting an anti-aging effect is not
> air-tight. What is needed is a false prediction from a postulated
> anti-aging effect of caloric restriction that could then be used in turn
> to falsify that hypothesis. I believe there exists one such prediction.
> Lower BMI is associated with reduced mortality in young and
> middle-aged humans. If caloric restriction retards the rate of aging and
> extends maximum life span in humans one must expect that a lower BMI
> would be significantly associated with reduced mortality in aged humans.
> If such an significant association is not found then caloric intake is
> not operative in modifying the rate of aging in humans and life spans
> beyond 120 will not be possible by reducing caloric intake.
> In humans over 84 years of age BMI has not been found to exert any
> significant effect on mortality. (New England Journal of Medicine 338:
> 1-7 1998 & Arch Intern Med 157: 2249-2258 1997) Therefore since no
> association has been found between BMI and mortality in aged humans, then
> caloric restriction is not operative in modifying the rate of aging in
> humans.
> The fact that caloric restriction dramatically extends life span in
> mice, but not apparently in humans requires some explanation. Here is
> one. In mice caloric restriction is associated with torpor, which can act
> to reduce tumor growth. In C57BL/6J mice blocking torpor, by increasing
> housing temperature to 30 C reduced the increase in average life span
> associated with caloric restriction from 47% to just 4%. Since humans
> neither experience torpor, nor suffer from cancer to the degree that mice
> do the effect of caloric restriction in mice can not be generalized to
> include humans. For example in human centenarians only 4% die from
> cancer. By comparison cardiovascular disease accounts for 63% of deaths
> in those aged 95 and over. (Epidemiology 8: 501-504 1997) Thus it is
> cardiovascular disease and not cancer that is the major longevity
> limiting factor in humans.
> It is possible that potassium intake may be a major dietary modulator
> of human longevity. A high potassium intake has been found to reduce
> stroke associated mortality to zero. (New England Journal of Medicine
> 316: 235-240 1987)
"The highest love [is] uniquely human,
the product of compassion and liberty;
not one at the expense of the other."
-- L. A. Chu and M. M. Butler

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