March 21, 2017


Other name(s):

a-amino-isocaproic acid

Unsubstantiated claims

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

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

Recommended intake

Amino acids (AAs) are available as individual AAs or in AA combinations. They also come as part of multi-vitamins, proteins, and food supplements. The forms include tablets, fluids, and powders.

Note that by eating enough protein in your diet, you get all of the amino acids you need.

You should take leucine supplements with valine and isoleucine.

There are no conditions that increase how much leucine you need.

Side effects, toxicity, and interactions

Using a single amino acid supplement may lead to negative nitrogen balance. This can decrease how efficient your metabolism is. It can also make your kidneys work harder. In children, taking single amino acid supplements may also cause growth problems.

You should not take high doses of individual amino acids for long periods of time.

Very high doses of leucine may cause low blood sugar (hypoglycemia). It may also cause pellagra. Symptoms of this condition can include skin lesions, hair loss, and gastrointestinal problems.

Women who are pregnant or breastfeeding shouldn’t use leucine supplements. People who have maple syrup urine disease (MSUD), a rare inherited issue, shouldn’t take either. They also shouldn’t take the other branched-chain amino acids. These include isoleucine and valine.


March 21, 2017

Reviewed By:  

Poulson, Brittany, RD, CDE,Wilkins, Joanna, R.D., C.D.