Leucine reduces appetite in lab rats

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More on Leucine:

" . . . .researchers found that injection of the amino acid L-leucine

into the hypothalamus of rats, the animals ate less. In fact, the

researchers found that L-leucine. . . .caused a decrease in food

intake four hours after administration, and lasted for 24 hours. "

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Could micronutrients be the future of diet design?

5/30/2006- Planning diets around key micronutrients like amino acids

could be the future of diet design and a way to help the fight against

obesity, says research published in Science.

Over 300m adults are obese worldwide, according to latest statistics

from the WHO and the International Obesity Task Force. About

one-quarter of the US adult population is said to be obese, with rates

in Western Europe on the rise although not yet at similar levels.

While macronutrients like fats and carbohydrates have traditionally

been the focus of diet design, the new research suggests that

micronutrients like specific amino acids could be used in the future.

" Rather than basing our diets only on macronutrients like fat and

carbohydrates, we might one day be designing diets based on

micronutrients like amino acids, " said lead researcher Randy Seeley in

a statement.

Scientists from the University of Cincinnati's Genome Research

Institute have reported that a signaling pathway of the protein,

mammalian Target of Rapamycin (mTOR), previously linked to the

development of diabetes and cancer, could play a key role in food intake.

" We take in calories to maintain levels of stored fuel (energy) and

adequate available fuel, " explained Seeley. " The signals that tell our

brain about both the stored and the available energy in our body can

activate the mTOR pathway in key parts of the brain that control

appetite. "

The researchers found that injection of the amino acid L-leucine into

the hypothalamus of rats, the animals ate less. In fact, the

researchers found that L-leucine (1.1 micrograms in 2 microlitres of a

phosphate-buffered saline solution) caused a decrease in food intake

four hours after administration, and lasted for 24 hours.

Interestingly, similar results were not observed when similar branched

chain amino acids like L-valine were used.

" The ability of L-leucine to activate mTOR in the hypothalamus and to

inhibit food intake may be an example of central nervous system

circuits using an evolutionary conserved signalling mechanism as a

fuel sensor rather than as an amino acid sensor, " wrote Seeley and

colleagues in the 12 May issue of Science (Vol. 312, pp. 927-930).

This fuel-sensitive pathway, said the researchers, could eventually

lead to a better understanding of obesity and type 2 diabetes.

In an accompanying editorial, Flier from Harvard Medical

School and Beth Israel Deaconess Medical Center, said that the

research asks several important questions, including how leucine

selectively regulates mTOR. Flier also said it was critical to

determine " whether normal physiological changes in amino acid

concentration act in the hypothalamus to influence energy balance and

metabolism. "

Seeley agreed, stressing that adding more leucine to the diet was not

a recommendation: " We still have a lot to learn about how these

nutrients would act if simply ingested with other nutrients, in what

form they could be most effective, and even if they are effective at

all when not administered directly to the brain, " he said.

Flier finished his editorial by saying: " The next challenge will be to

determine whether novel therapies for metabolic disease will emerge

from nutritional exploitation of these insights. "

The link between leucine and weight loss has already been reported in

the literature. Indeed, Brazilian researchers recently reported that a

0.6 per cent L-leucine supplement led to a 23 per cent reduction in

body fat for rats (Nutrition, Vol. 22, pp. 520-527).