Splanchnic lipolysis in human obesity
There is a close relationship between abdominal fat and metabolic disease. The theory is that excess visceral fat leads to increased free fatty acids (FFA) being released into the portal vein, thus exposing the liver to higher FFA concentrations. Increased liver exposure to FFAs could effect production of triglycerides, such as VLDL, and have an impact on hepatic insulin resistance. It has been difficult, however, to gain a solid assessment of the effect of visceral fat on hepatic FFA concentration in humans. Now Michael Jensen and colleagues, of the Mayo Clinic, have used isotope dilution/hepatic vein catheterization techniques to directly assess the contribution abdominal fat plays in distribution of FFAs to the liver. The researchers showed that abdominal fat contributed between 10%–50% to the delivery of FFAs to the liver and that this contribution was directly proportional to the amount of abdominal fat. Of greater interest, this study also showed that the correlation was greater in women than in men. These observations are consistent with previous studies that have indicated that there is a much better correlation between abdominal fat amounts and serum triglyceride levels in women than in men, and between abdominal fat amounts and hepatic insulin resistance index. This study, therefore provides the first detailed understanding of how abdominal fat, by increasing FFA concentration in the liver, correlates with the presence of increased risk for metabolic diseases in obese individuals.
An accompanying commentary from Samuel Klein provides an overview concerning the various placement of fat deposition in the body, and details how FFAs are derived from each of these areas. This commentary describes, using the work from this study and previous studies, how each of these areas of fat deposition contribute to systemic arterial circulation and portal circulation FFA levels and how each therefore may have varying impact on an individual's health.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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