Glutamine

Limited nutritional benefit

L-glutamine powder, the most abundant amino acid in the body; not essential.

Glutamine is the most plentiful amino acid in blood and muscle, and the body makes as much as it needs; a normal diet adds 5-10 g a day on top. Large doses matter in hospital medicine — burns, critical illness, some gut conditions — but in healthy people who train, studies have not found that 5-10 g a day builds muscle, speeds recovery or protects immunity. It is a protein amino acid and is counted as protein here, but it is not an essential one, so it does nothing for the day's amino-acid score.

As a supplement

Supplement page: dosing, interactions, lab tests →

Typical dose

5–10 g

1× a day

Times

Any time

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

Immune support
Digestion

What to know while taking it

It dissolves in water and its absorption does not depend on meals, so it can be taken with food or without. In the body it is broken down to glutamate and ammonia, which the liver has to clear; that is why the liver enzymes ALT and AST are the values worth following on a routine blood panel, especially where liver function is already impaired. Glutamine standing in solution slowly degrades, so the powder is mixed shortly before it is used rather than prepared in advance.

When to see a doctor

Yellowing of the skin or eyes, persistent nausea, dark urine or unexplained confusion point to the liver rather than the gut and mean it is time to see a doctor. A rise in ALT or AST that holds on a repeat test is the same signal in numbers.