英语语法分析

It has leucine to help you keep muscle.

它有亮氨酸，以帮助你保持肌肉。

Protein also contains leucine, an amino acid that prevents muscle loss when you're dieting.

蛋白质中含有亮氨酸，这是一种氨基酸能在你节食的时候阻止肌肉消失。

In short the term refers to three essential amino acids - leucine, isoleucine and valine.

总之这个词是指三个必需氨基酸-亮氨酸，异亮氨酸和缬氨酸。