Supplementing the diet of lab mice with leucine was associated with improvements in liver levels of fat and glucose. The study, published in the journal PloS One, may have implications for people at risk of diabetes or with metabolic syndrome.
"We found that adding just this one amino acid to the diet changed the metabolism in a lot of different pathways," said C. Ronald Kahn, MD, from Harvard Medical School and study leader.
"It had effects that improved insulin sensitivity, improved their ability to metabolize sugar and fats and their overall metabolism improved."
Dr Kahn stressed that the data is preliminary and it is therefore too early to make recommendations that people with pre-diabetes or metabolic syndrome add leucine to their diets. The next step should be a study in humans, he added.
Diabetes and MetS
Metabolic syndrome (MetS) is a condition characterized by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type-2 diabetes and cardiovascular disease (CVD).
Diabetes affects an estimated 24 million Americans, equal to 8 percent of the population. The total costs are thought to be as much as $174 billion, with $116 billion being direct costs from medication, according to 2005-2007 American Diabetes Association figures.
The new study, a collaboration between scientists from Harvard and Metabolon, Inc. (North Carolina), tested the effects of supplemental leucine (1.5 percent) on various metabolic markers in mice fed a high-fat diet.
"The impact on the animals on the high-fat diet, even though it didn't change how fat they got, was that their bodies were able to handle glucose better [after leucine addition to the diet]," said Kahn
"Their glucose tolerance tests improved," he said. "Their bodies responded to insulin better than they would have before they got the leucine. It improved their ability to metabolize sugar and fats. It markedly improved their pre-diabetic condition. Their metabolic syndrome also improved."
The researchers concluded that the data showed the importance of understanding the effects of individual nutrients, and not just the effects of macronutrients like protein, on the development of diseases like diabetes.
Source: PLoS ONE
Published online ahead of print, doi: 10.1371/journal.pone.0021187
“Dietary Leucine - An Environmental Modifier of Insulin Resistance Acting on Multiple Levels of Metabolism”
Authors: Y. Macotela, B. Emanuelli, A.M. Bang, D.O. Espinoza, J. Boucher, K. Beebe, W. Gall, C.R. Kahn