May 20, 2005
Tulane University researchers are the first to demonstrate a biological link between insulin resistance, weight gain and signs of early aging in the blood. Obesity has long been known to result in early death, but researchers don't fully understand the process of aging at the cellular level.
In a study published in this month's Circulation, Tulane University researchers demonstrate that people with insulin resistance and weight gain also have prematurely shortened white blood cell telomeres - a widely recognized sign of aging. Telomeres are part of each chromosome and naturally become shorter over time as cells multiply and reproduce.
"We know that obesity and insulin resistance place a physical burden on the body, leading to inflammation, the production of more blood to feed the body, and oxidative stress, all of which are important factors in the biology of aging," says cardiologist Gerald Berenson, co-author of the study. "It makes sense that we would see other signs of aging, like shortening of the white blood cell telomeres, as well," Berenson says.
Researchers analyzed blood drawn from 49 adults who participated in the Bogalusa Heart Study at least twice between 1988 and 2001. Researchers also analyzed data related to weight, blood pressure and diet and lifestyle factors. The researchers found that as people's weight and insulin resistance increased, they also experienced a shortening of the telomeres of their white blood cells. Insulin resistance is a reduced sensitivity in the tissues of the body to the action of insulin, a hormone that brings blood sugar (glucose) to those tissues to be used as a source of energy.
To compensate, the body works harder to produce more insulin while at the same time failing to lower blood sugar levels. The Bogalusa Heart Study is the longest-running, biracial, community-based study of heart disease risk factors beginning in childhood in the world. Since its inception in 1973, Berenson and his staff have screened over 16,000 adults and children in the Bogalusa, La. area in an effort to understand heart disease risk factors over the lifespan.
Children who began the study in the 1970s while they were in elementary school are now adults who continue to participate in the screening process. Moving from a pediatric study, the investigators now are studying aging. Funding for the research comes from the National Institutes on Aging and Heart, Lung and Blood.
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