leucine

February 1, 2001 by  
Filed under Amino acids

Leucine

Amino acid

Leucine is one of the branched chain amino acids. It cannot be made by the human body, and is particularly involved in stress, energy and muscle metabolism. Leucine is a purely ‘ketogenic’ amino acid – that is to say it is metabolized through fat pathways.

This amino acid is particularly good at stimulating protein synthesis. It also inhibits protein breakdown, and can substitute for glucose, providing an alternative, and perhaps superior, energy source for the body. Because of its ability to maintain blood sugar levels, some doctors believe that leucine, with other nutrients, may be a more ideal energy source than glucose in intravenous feeding solutions, particularly as branched chain amino acids (BCAAs) decrease the rate of breakdown and utilization of other amino acids.

A high intake of leucine can decrease brain serotonin and dopamine concentrations and, by increasing the excretion of vitamin B3 in the urine, can worsen the psychotic symptoms of pellagra, the vitamin B3 deficiency disease which has been likened to schizophrenia. Leucine is more highly concentrated in foods than other amino acids. Milk and pork are particularly good sources.

Vegetarian sources: Weight for weight, soya protein concentrate, soya flour, peanuts, tofu, almonds and pumpkin seeds are as rich in leucine as animal proteins.

Availability of supplements: Usually available only in combined BCAA products.

Linda Lazarides is Course Director of the School of Modern Naturopathy and author of eight books on health, nutrition and naturopathy.

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