The most abundant amino acid in the body.
Why it’s used: A fuel for the cells that line the gut and for immune cells.
L-glutamine is the most abundant amino acid in the body. The body makes its own, so it is not classed as an essential amino acid, and it is also found in protein-rich foods such as meat, fish, eggs, dairy, beans and lentils.
Glutamine is a fuel for the cells that line the gut and for immune cells, which is why it is popular with people who train hard and in gut-focused formulas. However, the European Food Safety Authority has reviewed proposed claims for glutamine relating to muscle mass, recovery after exercise, gut permeability and immune responses, and concluded that a cause-and-effect relationship had not been established. No health claims are authorised for it in the UK.
On labels it is usually listed as L-glutamine, most often as an unflavoured powder or in capsules. Researchers have studied a wide range of amounts. A 2020 pilot study found that single doses of up to 0.9g per kilogram of fat-free mass were generally tolerated by healthy adults, with mild stomach symptoms becoming more likely at the higher doses.
2 findings behind this ingredient. Hover a card for the detail and the source.
106 adults with post-infectious IBS-D took 5 g glutamine or placebo three times daily for 8 weeks. 79.6% met the primary endpoint versus 5.8% on placebo.
Runners and elite rowers received glutamine or placebo after exhaustive exercise and recorded infections for 7 days. Infection levels appeared lower and T-helper/T-suppressor cell ratios higher with glutamine.
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L-glutamine is a fuel for the cells lining the gut and for immune cells, which is why it appears in sports and gut-focused formulas. EFSA has reviewed claims about muscle, recovery, immunity and gut health and found them not established, so it carries no authorised health claims.
Short-term studies in healthy adults suggest it is generally tolerated, with mild stomach symptoms at high doses. Long-term high intakes have not been well studied. A 2008 risk assessment proposed 14g a day as an observed safe level for supplemental glutamine.
The body makes its own glutamine, and it is also found in protein-rich foods, so it is not an essential nutrient. Some people choose it as part of a training or gut-focused routine, but benefits for healthy people have not been established.
Information only, not medical advice. If you take medication, are pregnant or breastfeeding, speak to your GP or pharmacist first.
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