L-Glutamine
The most abundant amino acid in the body and a key fuel for the gut lining and immune cells. Genuine evidence in niches (gut barrier, immunity under extreme load) — but overrated as a muscle-building supplement in healthy people.
How it works
L-glutamine is the most abundant free amino acid in blood and the preferred fuel for fast-dividing cells, especially the gut lining and immune cells. On a normal diet the body is well supplied; extra intake matters mainly under extreme stress, severe injury or gut problems. The popular muscle and performance benefits in healthy people are thinly supported.
Dosage
Typically 5 g/day. Gut/immune studies sometimes use higher doses (10–30 g/day, clinically supervised).
Considerations
An honest take: in healthy, well-fed athletes the benefit for muscle growth and recovery is weakly supported — oral glutamine is largely consumed by the gut and liver before it reaches muscle. Meaningful benefit is mostly in gut issues (barrier function) and catabolic/clinical states. Important: many tumors are glutamine-dependent — if you have cancer, only take it after consulting your treating physician.
