$12.4 million for study of nutrition and aging.
April 23, 2002
The Pennington Biomedical Research
Center has been awarded a seven-year, $12.4 million
grant from the National Institutes of Health to study
the possible benefits of a long-term reduction of calories
on aging. The grant is the largest ever by the NIH
to the Pennington Center in its 14-year history.
The study will look at whether a
two-year calorie deficit reduces the risks of age-related
chronic diseases-such as heart disease, hypertension
and type 2 diabetes-and leads to longer and more productive
The theory is based on studies of animals, which show that restricting
calories-whether from birth, or beginning in adulthood-prolongs life.
Animals that receive a quality diet, but one that is lower in calories,
live longer than those consuming more calories per day.
The mechanisms through which caloric
restriction acts to extend life are unclear. It is
also not known whether this same effect occurs in humans.
"It is important to understand
that we are talking about restricted-calorie diets
that are high-quality and nutrient-dense," says
the study's principal investigator, Dr. Eric Ravussin. "If
the quality of the diet is poor and insufficient in
some vitamins and essential nutrients, we wouldn't
see any benefits, but rather the same problems observed
when poor nutrition is practiced."
This program will expand understanding of the relationship between caloric
restriction and health in humans, since there have been only two previous
studies, both of which were limited in scope.
One, a survey of the Japanese island
of Okinawa found that the incidence of individuals
100 years or older is two to 40 times greater than
the general Japanese population. The total energy,
however, consumed by school children on Okinawa is
only 62 percent of the recommended intake for Japan.
For adults, intake was about 20 percent less than the
Another study compared individuals
receiving 2,300 calories per day with another group
receiving only 1,500 calories over three years. The
results were mixed. Visits to the infirmary were reduced
considerably in the restricted-calorie group, but mortality
rates weren't significantly changed.
A key part of the Pennington Center
study will be to use a variety of techniques for analyzing
the impact of caloric restriction on metabolism, which
is the system the body uses to burn energy and function
day-to-day. "The thinking is that caloric restriction
may change how the body's metabolism handles the food," says
Ravussin, professor and chief of the Pennington Center's
Division of Health and Performance Enhancement. "These
changes may play significant roles in the aging process."
Additionally, the program will observe
whether similar results can be achieved by increasing
activity levels. Genes that may control responses to
caloric reduction and its effects on aging and chronic
diseases will also be examined.
Pennington Center Executive Director
Dr. Claude Bouchard says the NIH grant provides the
resources for the facility's first step into studying
caloric restriction. "This area holds enormous
promise for health and prevention of chronic disease.
But counseling volunteers in this study to eat fewer
calories each day than they need to feel full and satisfied
will be an enormous challenge. "He says the question
of whether quality of life can be improved and perhaps
even prolonged by eating less is a fundamental biological
and behavioral issue that needs answering. "I
am pleased and excited that the Pennington Center was
chosen to play a leadership role in this important
field of research."
Approximately 100 men and women will
be studied for two-years. Enrollment in the program
is not expected to begin, however, until later this
Ravussin's collaborators on the project
include Drs. Bouchard, James Delany, Andy Deutsch,
Paula Geiselman, Frank Greenway, Mike Lefevre, Marlene
Most, Steve Smith, Julia Volaufova, and Don Williamson.