Leucine has a very unpleasant taste and poor solubility, making it difficult to consume at higher doses.

“because that's the leucine's horrible right oh yeah you know I used to I might have even told you I used to spike five grams of leucine into my water during a workout I mean it's the most awful tasting is do any other is there any other amino acid that tastes as bad as leucine probably some of the sulfur-based ones yeah you know cysteine or uh methionine yeah um no it's pretty bad and the fact it's also nonpolar so it doesn't dissolve yeah it doesn't dissolve well you're shaking it constantly yeah”