In research scheduled for presentation at the 11th International Symposium on Amino Acids, to be held in August, 2009 in Vienna, Austria, scientists at Texas A & M University have shown that the amino acid arginine helps reduce fat gain in obese rats, a finding that may prove to be useful against human obesity. The study, which was funded by the American Heart Association, was published in the February, 2009 issue of the Journal of Nutrition.

Texas A & M department of animal science Senior Faculty Fellow Guoyao Wu and associates fed 24 rats a high fat diet and gave 24 a low fat diet starting at 4 weeks of age. After 15 weeks, 8 rats from each group were examined. Animals who received the high fat diet, which provided 40 percent of its calories in the form of fat, experienced 18 percent greater weight gain and 74 percent higher white fat pad weight compared to rats that received the low fat diet, which provided only 10 percent of its calories from fat. (White adipose tissue is the most common form of fat storage in humans, as opposed to brown fat.) The remaining animals in each group were subsequently divided to receive drinking water supplemented with 1.5 percent L-arginine or 2.55 percent L-alanine (as a control) while otherwise maintaining their previous diets.

After twelve-weeks of supplementation, body weight gain in the rats receiving the high fat diet was 40 percent lower among those that received arginine compared with the control group. For rats on the low fat diet, weight gain was 60 percent lower in the arginine group compared with those that received alanine. White fat pad weight increased by 98 percent in animals that received alanine; while in animals that received L-arginine the increase averaged only 35 percent. Arginine supplementation was also associated with lower serum leptin, glucose, triglycerides, urea, glutamine, and branched chain amino acids, as well as improved glucose tolerance.

The researchers concluded that arginine promotes lean tissue growth over fat gain, a finding that was observed in earlier research using pigs. Dr Wu stated that future investigations will involve obese children and adults.

"Given the current epidemic of obesity in the U.S. and worldwide, our finding is very important,” stated Dr Wu. “This finding could be directly translated into fighting human obesity. At this time, arginine has not been incorporated into our food (but could in the future).”