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Study finds expanding waistline may bring fatty liver disease
By LOIS BAKER
Contributing Editor
A new UB study has found that excessive fat around one's middle—the familiar "potbelly"—is a strong predictor of potential liver damage.
The study, published in Hepatology, showed that abdominal height, a measure of central fat accumulation, was more closely related to elevated levels of two markers of liver function—ALT and GGT—than body-mass index (BMI), a measure of relative weight.
It is the first population-based study to show that the way body fat is distributed is more important than overall adiposity in the development of potential liver damage.
Moreover, abdominal height followed by BMI were the most powerful independent predictors of increased levels of ALT in both men and women, and of both ALT and GGT in women—factors more important even than alcohol consumption.
The findings have implications for how physicians monitor their patients, said Saverio Stranges, research scientist in the Department of Social and Preventive Medicine in the School of Public Health and Health Professions.
"Physicians have to be careful not to limit their assessment to weight and BMI when determining their patients' health status," said Stranges. "It is important to assess where fat is located, not just overall pounds." Central adiposity (an "apple" shape rather than a "pear" shape) also has been linked to impaired lung function, diabetes and cardiovascular disease.
The current study involved 2,704 people between the ages of 35 and 80 selected randomly from the population of two Western New York counties. All participants were free of known liver disease and heart disease. Researchers collected measurements of height, weight, body-mass index, waist circumference, waist-to-hip ratio and abdominal height from all participants, as well as data on age, race, education, smoking and drinking habits. Abdominal height was measured with a special caliper while each participant lay flat on the back.
Fasting blood samples were collected and analyzed for the liver enzymes ALT, AST and GGT, the most widely used markers of liver function. An increase in any of these enzymes indicates stress on the liver, even when there are no physical symptoms of disease.
Results showed that abdominal height consistently was more closely associated with ALT and GGT levels than BMI in both sexes. When all the variables, including alcohol consumption, were included in the analysis, abdominal height and BMI remained the most closely associated with increased enzyme levels and potential liver damage. Among women, the relationship tended to be stronger in younger versus postmenopausal women, findings showed.
"The tendency toward developing an apple shape or a pear shape when we put on pounds is determined by both genetic and environmental factors," said Stranges. "The message, however, is to not put on the pounds in the first place if people want to keep their liver healthy."
Additional researchers on the study from the School of Public Health and Health Professions are Joan Dorn, Paola Muti, Jo Freudenheim and Maurizio Trevisan. Eduardo Farinaro from the University of Naples Medical School, Italy; Marcia Russell from the Prevention Research Center, Berkeley, Calif., and Thomas Nochajski from the UB School of Social Work also contributed to the study.
The research was supported in part by a grant from the National Institute on Alcohol Abuse and Alcoholism.