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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 national average.
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 summer.
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.
Please visit the CALERIE web site for more information.
The Pennington Biomedical Research Center is at the forefront of medical discovery as it relates to understanding the causes of obesity, diabetes, cardiovascular disease, cancer and dementia. Itis a campus of the Louisiana State University System and conducts basic, clinical and population research. The research enterprise at the Center includes approximately 80 faculty and more than 25 post-doctoral fellows who comprise a network of 50 laboratories supported by lab technicians, nurses, dieticians, and support personnel, and 19 highly specialized core service facilities. The Center's more than 500 employees perform research activities in state-of-the-art facilities on the 234-acre campus located in Baton Rouge, Louisiana.