Amino acids are the building blocks your body uses to make proteins, which do nearly everything—from building muscle and bone to making enzymes and hormones. Your body can produce some amino acids on its own, but nine of them must come from food; these are called essential amino acids. Understanding which foods contain them, how your body uses them, and whether you need supplements helps you make informed choices about your diet.

The articles here explore what amino acids actually do in your body, which foods provide them, and what the research shows about claims made around amino acid supplements, protein timing, and specific health goals. You'll find information about how amino acid needs vary by age and activity level, and what questions remain open in the science.