L-Glutamine

What is L-glutamine?

L-glutamine is an amino acid, one of the building blocks of protein. It's classed as non-essential because your body can make it, and it's also present in the protein you eat.

"L-glutamine" and "glutamine" mean the same thing on a supplement label; the L refers to the form found in food and in the body. Glutamine peptides, also stocked here, are glutamine bound to other amino acids.

Foods that contain protein, such as meat, fish, eggs, dairy, beans and lentils, all provide some glutamine. A glutamine supplement simply supplies it on its own, without the other amino acids in a protein food.

What does glutamine do?

In the body, glutamine is used to make protein and has many other roles. As a supplement for healthy people who train, a 2019 review found that glutamine supplementation seems to have limited effects on physical performance.

The same review reported changes in some blood markers linked with fatigue and muscle damage, but many of those findings came from animal studies, and the authors said more research is needed.

What are the benefits of L-glutamine?

There are no authorised health claims for glutamine in Great Britain, so we can't say it has any specific benefit. The authorised claims list has no entry for glutamine, including for muscles, recovery, immunity or gut health.

The 2019 review notes that the International Society of Sports Nutrition and the International Olympic Committee rate glutamine as having little or no proven efficacy for athletes. "Where evidence is limited or inconclusive, we should say so openly," says Andy Arshad, who runs SupplementHQ.

Is L-glutamine good for gut health?

We can't say that it is. People do search for glutamine for gut health, but no gut-health claim for glutamine is authorised in Great Britain, and the sports-nutrition research we've looked at doesn't cover it.

If you have digestive symptoms or a bowel condition, speak to your GP or pharmacist rather than choosing a supplement yourself.

Do you need glutamine if you eat enough protein?

Probably not. Glutamine is part of the protein in your diet, and the British Dietetic Association says a varied, well-balanced diet should provide the nutrients and energy required for sport.

A 2026 review of amino acid supplements says supplementing an amino acid may be relevant to correct a shortfall in specific situations, and warns against taking excessive amounts. Compare glutamine with protein powder and EAA supplements if you're unsure.

Glutamine powder or tablets?

Powder usually costs less per gram of glutamine than capsules, and it's often unflavoured so you can add it to a drink. Capsules and tablets are convenient but contain much less per unit.

How to compare value

How to compare value (example figures, not real products): a £15 tub of 500g glutamine powder at 5g a serving gives 100 servings, 15p a serving. A £12 pot of 120 capsules with 750mg each gives 90g in total; at 5g a day that's 18 servings, about 67p a serving, more than four times as much for the same amount.

"We think customers should compare the actual amount of active ingredients they're getting, rather than just the format or marketing," says Andy. Our guide to reading a supplement label shows where to find the amounts.

Which is the best glutamine supplement?

If you've decided to try one, the best for you states the grams of glutamine per serving clearly and has a sensible cost per serving. A blend with BCAAs or EAAs may contain less glutamine than a plain powder.

If you have a medical condition, take medication, or are pregnant or breastfeeding, speak to your GP or pharmacist first. Browse the rest of our amino acids & recovery range.

We sell the products on this page. That's our commercial interest, and it's why we show the evidence alongside them. This page is general information for adults, not personalised medical advice. Food supplements should not replace a varied, balanced diet.

Written by Andy Arshad, SupplementHQ. Last reviewed 11 October 2026.