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Can Cutting Calories Increase Longevity?
Check the latest research |
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On caloric restriction and various disease
prevention strategies? |
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Research into the possible use of caloric restriction to prevent or delay
age-related diseases is focusing on several areas:
 Immune
function
Atherosclerosis
Cancer
Other
disease prevention in humans
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Immune function |
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The ability to resist infection declines with age, in animals and in
humans. In mammals, at least some of this impairment of immunity is
believed to be due to a decline in the function of specialized white
blood cells called T cells. In a Japanese study of calorie-restricted
mice32, T-cell function was dramatically better than in the
freely fed mice. Whether this will translate to better infection fighting
ability remains to be determined.
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Atherosclerosis |
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Atherosclerosis or hardening of the arteries leads to heart disease and
stroke. Many factors, such as high blood pressure, smoking, diabetes and
aging itself, accelerate atherosclerosis. To study the effects of caloric
restriction on the risk factors and the development of atherosclerosis
in primates33, researchers placed 33 cynomolgus monkeys on
a diet restricted to 70% of the norm. The scientists evaluated these animals
regularly over four years and found they have less visceral body fat accumulation
and better insulin sensitivity. There was no difference in the calorie-restricted
animals' blood cholesterol levels as compared to freely fed monkeys. Although
the restricted monkeys' risks for atherosclerosis would appear to be less
than their normal counterparts, in fact, there was no difference in the
amount of atherosclerosis found in the aortas of the two groups. The next
phase of the study will look at the equally as important coronary and
carotid arteries.
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Cancer |
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The incidence of many cancers increases with age. Certain long-lived strains
of mice are noted for their high risk of developing lymphoma (cancer of
the lymph nodes) and hepatoma (liver cancer). In a University of Wisconsin
study, that strain subject to caloric restriction had a cancer incidence
of 38% compared to the freely fed control mice, whose tumor incidence
was 78%34. Another study in mice documented that caloric restriction
reduced the rate of all cancers by about half35.
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Other disease prevention in humans |
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Most studies of caloric restriction in humans have been preliminary, observational
and involving few subjects. One famous (and inadvertent) study took place
in Biosphere II, intended to be a self-contained, self-sustaining greenhouse
and colony in the desert of Arizona. Unanticipated problems with food
production led to a reduction in the participants' daily calorie intake
to about 1,500 calories per day, largely in the form of grains, vegetables,
beans and fruits. Gerontologist Roy Walford of UCLA, a participant himself
and one who has followed a calorie restricted diet voluntarily for years,
studied his fellow calorie-restricted subjects. He found improvements
in their total blood cholesterol levels36, blood pressure and
glucose levels. The study was too short and the participants too young,
so extrapolations to aging adults are premature, but the results are provocative
nevertheless.
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