In obese people with nonalcoholic fatty liver disease (NAFLD), fat from the diet ends up "stuck" in the liver, where it doesn't belong. It was known that the livers of NAFLD patients accumulated fat, but its origin was unknown. The new work implicates fat from the diet as one cause of NAFLD and shows that fat buildup in the liver results when the liver loses its ability to manage the various influxes of fat that occur during transitions between the fasted and fed states. Identifying the origins of accumulated fat in the livers of NAFLD patients will be important in preventing and reversing this condition, which can lead to more serious liver trouble. The work will be published May 2 in the Journal of Clinical Investigation.

"This is the first scientific proof of dietary fat stored in the liver in humans," said Elizabeth Parks, an associate professor of human nutrition, who led the study. "In health, it's the liver's job to store glycogen--a storage form of carbohydrates--not fat." The clear implication is that too much dietary fat leads the liver to fail in its mission as the body's central shipping and receiving center for fat. No longer does it take in dietary fat, repackage it and send it on its way back out into the blood. In obesity, fat builds up in the liver. The fat comes both straight from the diet and also from sugars that the liver turns into fat. As a result, the liver functions poorly.

In healthy people, about half the fat from a meal is burned for energy, and the rest is shunted to adipose tissue, where it is stored until needed during fasting. Very little fat is normally stored in the liver.

Working with obese subjects who had NAFLD, Parks and her colleagues fed the subjects food containing fats labeled with deuterium, a rare but stable form of hydrogen that can
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Contact: Deane Morrison
morri029@umn.edu
612-624-2346
University of Minnesota
2-May-2005