Why use Mass Leucine Powder? Mass Leucine Powder contains pure leucine, a branched-chain amino acid that cannot be synthesised by the body and is therefore recommended as a supplement. Who can benefit from a leucine amino acid sports supplement? A leucine amino acid supplement typically contains more leucine per serving than a sstandard scoop of whey protein. A leucine supplement, then, could be particularly beneficial for people looking to increase their leucine intake without supplementing with whey powder. Learn more about the uses of amino acids in sports supplementation with the Mass Guide to Amino Acid Supplements on our blog.