Leucine is one of the three essential branched-chain amino acids (BCAAs), which together with valine and isoleucine accounts for 15-25% of our protein intake. Leucine’s unique role in promoting metabolic regulation has a number of beneficial effects. By promoting protein synthesis, Leucine helps in the maintenance and development of muscles. In addition, Leucine improves glucose and insulin tolerance by producing the amino acid alanine, which aids blood glucose control by producing glucose in the liver. The impact of Leucine on these metabolic regulatory functions is proportional to dietary intake.
Leucine has a number of positive effects on exercise and diet. It is valued by bodybuilders for its ability to develop muscles and produce energy during exercise. In dieting, Leucine helps burn calories by changing the metabolism of amino acids to increase the amount of energy expended. Notably, while increased Leucine intake may change body composition, it has been shown to spare lean body mass while controlling insulin and glucose levels. With the two other BAAs, isoleucine and valine, Leucine is used to treat chronic liver disease, including hepatic encephalopathy, a form of liver disease found in alcoholics. Although rare, Leucine deficiency can result in hypoglycemic symptoms, including fatigue, headaches, and dizziness. An inability to metabolize leucine, valine and isoleucine is known to cause Maple syrup urine disease (MSUD).
Leucine is found in meat, legumes, soy beans, nuts, brown rice and whole wheat. High leucine content is found in whey isolate and casein (milk). It is recommended that a daily required dosage per kilogram of body weight of 10 – 18 g of Leucine is taken through food and supplementation. For exercisers taking leucine supplements, 20-40 g of whey protein is recommended before and after workouts.
The metabolism of BCAAs may be improved by combining them with other nutrient supplements, such as B12 and biotin.
High amounts of amino acids may disrupt liver and kidney function, cause headaches, skin hypersensitivity, and hallucinations, and increase the amount of ammonia in the body.
References:* “The secret of 'muscular' old age” Electronic source, 2007. http: news.bbc.co.uk-2 hi-health-4502862.stm
* “Leucine: Amino muscle builder- Advanced Nutrition” Electronic source, (http: findarticles.com-p-articles-mi_m0KFY-is_5_2-ai_103376715pg_1)
* Burning extra calories with a futile protein cycle, www.newsrx.com-health-article
