Health Library Content

Leucine

Other name(s):

a-amino-isocaproic acid

Unsubstantiated claims

Please note that this section reports on claims that have NOT yet been substantiated through scientific studies.

Leucine may improve healing of skin and bones, increase muscle development and lean body mass, increase production of human growth hormone (HGH), and help control blood sugar.

Recommended intake

Amino acids (AAs), such as leucine, are available as individual AAs or in proprietary AA combinations, as well as part of multi-vitamin formulas, proteins, and food supplements. The forms include tablets, fluids, and powders. However, adequate protein in the diet should provide a sufficient source of all amino acids.

Leucine supplements should be taken together with valine and isoleucine.

There are no conditions that increase the nutritional requirements for leucine.

Side effects, toxicity, and interactions

The use of a single amino acid supplement may lead to a negative nitrogen balance, decreasing metabolic efficiency and increasing workload in the kidneys. In children, taking single amino acid supplements may also harmfully affect growth parameters.

Very high doses may cause low blood sugar (hypoglycemia) and pellagra (symptoms of which include skin lesions, hair loss, and gastrointestinal distress).

Always avoid taking individual amino acids in high dosage for prolonged periods.

Women who are pregnant or breastfeeding should not use leucine supplements.

Individuals who have maple syrup urine disease (MSUD), a rare inherited disorder, should avoid leucine and the other branched-chain amino acids (isoleucine and valine).

Additional information

Click here for a list of reputable websites with general information on nutrition.

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