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From att!K.ERGO.CS.CMU.EDU!Timothy.Freeman Sun Oct 7 17:50:45 1990
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Subject: CRYONICS - Notes on dietary restriction
Date: Sun, 07 Oct 90 17:41:14 EDT
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Recently I read _The Retardation of Aging and Disease by Dietary
Restriction_ by Weindruch and Walford [Weindruch88]. This is a more
scholarly followup to Walford's books _The 120 Year Diet_ [no
reference] and _Maximum Life Span_ [Walford83].
The vast majority of the book discusses evidence that dietary
restriction increases both the average and the maximum life span for
animals. He presents evidence that it works with insects, various
microorganisms, and fish. Then he discusses the work that has been
done on rats and mice, which is much more detailed than the work that
has been done on other animals. His last chapter is about application
of dietary restriction to humans.
The data for humans (and other primates) is skimpy compared to the
data for other animals. There are studies of the population in
Okinawa as compared to the population of Japan as a whole, and
there was a study of people in an old-age home in Madrid in 1957.
The average Okinawan calorie intake is only 80% of the average
Japanese calorie intake. Other aspects of their diet seem to be
better than the diet in Japan. They also get more exercise. The
Okinawans seem to be healthier than the Japenese; for instance, the
death rate of people aged in the range 60-64 years is 1280 per 100,000
in Okinawa and 2181 per 100,000 in Japan.
The study in the old-age home in Madrid was carried out by Vallejo
[Vallejo57]. The control group ate ordinary institutional food with
2300 calories per day. The study group ate the ordinary food on
alternate days, and on the remaining days they were limited to one
liter of milk plus 500 g of fresh fruit. There was a significant
decrease in number of days spent in the infirmary for the restricted
group. Six people in the restricted group and 13 in the control
group died, but this difference wasn't statistically significant.
There is also some evidence concerning adult-onset anorexia. During
the early stages of anorexia, the immune systems of the patients are
at least as effective as those of people without anorexia.
The authors recommend in the last chapter to begin restriction in
early adulthood, since restricting the diets of children stunts their
growth. They also recommend losing weight slowly, since too-rapid
weight reduction by dietary restriction doesn't extend lifespan in
laboratory animals. In Walford's earlier book [Walford83], by scaling
up the rate of weight loss that seems to work best for rats to a
human-length life time and body weight, he recommends losing weight at
roughly 1/2 pound per month, until you weigh somewhere between 10 and
25% below your setpoint. He considers the setpoint to be the weight one
kept stably in the 20's-30's.
Older people can still benefit from dietary restriction, but they need
to lose weight more slowly.
Tim
References:
@book ( WEINDRUCH88,
key = "Weindruch88" ,
author = "Richard Weindruch and Roy L. Walford" ,
title = "The Retardation of Aging and Disease by Dietary
Restriction" ,
publisher= "Charles Thomas" ,
address = "Springfield, Illinois" ,
year = "1988" ,
keywords= "diet, tsf" ,
annote = "Falk library has it, call number Qp86 W423 1988" ,
)
@book ( WALFORD83,
key = "Walford83" ,
author = "Roy L. Walford" ,
title = "Maximum Life Span" ,
publisher= "W. W. Norton and Company" ,
address = "New York" ,
year = "1983" ,
keywords= "longevity, tsf" ,
annote = "Falk library has it, QP85 W17 1983" ,
)
@article ( VALLEJO57,
key = "Vallejo57" ,
author = "E. A. Vallejo" ,
title = "La dieta de hambre a dias alternos in la
alimentacion de los viejos" ,
journal = "Rev Clin Exp" ,
volume = "63" ,
number = "25" ,
year = "1957" ,
keywords= "diet, longevity, tsf" ,
note = "As referenced in Weindruch88." ,
)
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