What are amino acids?
Amino acids are the small building blocks that link together in chains to form proteins, the molecular machines and structures of your body.
Think of amino acids as LEGO bricks. There are about 20 kinds, and by snapping them together in different orders, your cells build thousands of different proteins, from muscle fibers to enzymes.
Why it matters for aging
Of the roughly 20 amino acids used to build proteins, nine are "essential": your body can't make them, so they must come from food. Animal proteins, soy and combinations of plant proteins provide all of them.
Amino acids also act as signals. Leucine, for example, switches on mTOR, the cell's growth switch, which is useful for building muscle. Some molecules called amino acids, like taurine, aren't used to build proteins at all but have other jobs.
A common myth
You need special amino acid supplements to build muscle.
Most people get all the amino acids they need from enough protein in a normal diet. Leucine, one amino acid, is a strong signal for muscle building, which is why protein-rich meals after strength training help.
Go deeper
Deep dives
- mTOR and aging: the growth switch you want on, and off
- Taurine and aging: the breakthrough, and the plot twist
Related terms
Updated Nov 9, 2026 · All terms