Does glutamine build muscle?

Not meaningfully in healthy, well-fed people, despite its reputation. Total protein and training drive muscle far more.

Will it heal a 'leaky gut'?

It fuels the gut lining and has a role in gut-barrier health, but strong evidence in healthy people is limited. It's more established in clinical stress situations.

Generally well tolerated. People with liver or kidney disease should check with a provider before using it.

L-Glutamine: Benefits, Dosing & Evidence

What it is

Glutamine is the most abundant amino acid in the body and a primary fuel for the cells lining the gut and for immune cells. The body usually makes enough, but demand can rise during major physical stress.

How it works

Glutamine is the most abundant amino acid in the body and the primary fuel for the fast-dividing cells that line the gut and for many immune cells. Under ordinary conditions your body makes plenty, but during major physical stress — serious illness, injury, or intense prolonged training — demand can outstrip supply, which is the rationale for supplementing in those specific situations.

What it's been studied for

Taken to support gut-barrier health and, in athletes, recovery.

What the evidence shows

Glutamine has a clear role in gut and immune-cell metabolism, but evidence that supplementing benefits healthy, well-nourished people is limited. It's more established in specific clinical settings than for general use.

Who should consider it

It's used mainly for gut-barrier support and, among athletes, recovery. The strongest rationale is in clinical settings of high physiological stress; in healthy, well-nourished people the everyday benefit of supplementing is limited, since the body usually makes enough. People with liver or kidney disease should get individualized advice.

Amounts commonly studied

Studies use a wide range, often around 5 g per day for general use.

How to take it

Studies use a wide range, often around 5 g per day for general use, taken with water; larger amounts are used in specific clinical contexts. It's flavorless and mixes easily. For gut support it's typically taken consistently over weeks.

Forms & absorption

L-glutamine powder or capsules; also present in protein-rich foods.

Food sources

Abundant in protein-rich foods — meat, fish, eggs, dairy, and to a lesser extent beans, tofu, cabbage, and spinach. A protein-adequate diet supplies substantial glutamine.

Safety & interactions

Generally well tolerated. People with liver or kidney disease should get individualized advice.

Myths & what it won't do

Myth: glutamine dramatically boosts muscle growth. Reality: despite its popularity in fitness circles, it hasn't been shown to meaningfully increase muscle or strength in well-fed people. Myth: everyone needs extra glutamine for gut health. Reality: the clearest benefits are in high-stress or clinical situations; for most healthy people the body already makes enough.

Common questions

Does glutamine build muscle?: Not meaningfully in healthy, well-fed people, despite its reputation. Total protein and training drive muscle far more.
Will it heal a 'leaky gut'?: It fuels the gut lining and has a role in gut-barrier health, but strong evidence in healthy people is limited. It's more established in clinical stress situations.
Is it safe?: Generally well tolerated. People with liver or kidney disease should check with a provider before using it.

The amounts listed here are what published research has used — not a prescription or a recommended dose for you. Confirm anything you plan to take with your own healthcare provider, especially if you take medications, are pregnant or nursing, or have a health condition.

L-Glutamine