Amino acid
HMB
HMB (beta-hydroxy-beta-methylbutyrate) is a substance the body makes from the amino acid leucine. It is mostly studied for muscle preservation.
Also listed as Hydroxy-MethylButyrate, beta-hydroxy-beta-methylbutyrate
Calcium salt or free acid?
HMB is sold as a calcium salt and a free acid. The free acid reaches the blood faster, but better absorption has not established better training outcomes. A 3 g dose of the calcium form also supplies roughly 400 mg calcium. 1