Meta-analysis: does glutamine reduce intestinal permeability?

Glutamine: a key amino acid for intestinal health

An abundant and versatile amino acid

Glutamine is one of the most abundant amino acids in the body, both in the blood and in the muscles.

It is naturally synthesised by the body, but is also supplied through the diet, particularly via meat products, eggs and legumes.

This amino acid plays a fundamental role in numerous physiological functions, including protein synthesis, acid-base balance and immune response (1).

But it is particularly in the intestinal tract that its functions are attracting the attention of researchers (2).

Essential fuel for the intestinal barrier

In the digestive system, glutamine is considered to be the main fuel for enterocytes, the cells that make up the intestinal mucosa.

These cells ensure the integrity of the intestinal wall, which plays a crucial role: it forms a selective barrier between the contents of the intestine and the rest of the body, contributing to the normal functioning of the digestive system.

This barrier function is based on the close cohesion of intestinal cells, maintained by tight junctions, protein complexes that 'seal' the cells together.

When these junctions are altered, intestinal permeability increases: this is known as the 'leaky gut' phenomenon.

This dysfunction is suspected of being involved in a number of chronic inflammatory or digestive disorders, such as irritable bowel syndrome, certain food allergies and autoimmune diseases (3-4).

Why is intestinal permeability a problem?

The intestinal wall acts as a selective filter: it helps essential nutrients to pass through, while also helping to limit contact with certain substances in the food we eat.

When its function is altered, the permeability of the intestinal epithelium can change. This has drawn the attention of researchers to its role in maintaining a balanced digestive system.

The resulting permeability issue is now suspected of being involved in a number of diseases:

• irritable bowel syndrome (IBS)
• chronic inflammatory bowel disease (IBD), such as Crohn's disease
• certain mood or cognitive disorders, via the intestine-brain axis
• chronic fatigue or 'mental fog', linked to low-grade inflammation

While the exact link between intestinal permeability and these pathologies remains under debate, research is converging on the importance of diet, lifestyle and intestinal microbiota in maintaining an effective barrier (5).

In this context, glutamine is of increasing interest to researchers, particularly for its role in preserving tight junctions and repairing damaged intestinal mucosa.

Results of the meta-analysis: promising effects of glutamine on permeable intestine

A recent meta-analysis published in 2024 compiled the results of several clinical studies evaluating the effect of glutamine on intestinal permeability (6).

A significant reduction in intestinal permeability

The meta-analysis included the results of 10 studies conducted between 1998 and 2014, in people with digestive disorders (inflammatory bowel disease, irritable bowel syndrome, etc.) and in healthy subjects.

The main conclusions? Glutamine supplementation is associated with a reduction in intestinal permeability when the dose administered exceeds 30 mg/day.

Glutamine may act by restoring the integrity of tight junctions, stimulating intestinal cell proliferation and limiting inflammatory processes (7-8).

More marked effects in people suffering from digestive disorders

The meta-analysis also highlights that the beneficial effects of glutamine are particularly noticeable in individuals with an already impaired intestinal barrier, such as patients suffering from inflammatory diseases or chronic gastrointestinal disorders.

In healthy subjects, the effect is more modest, but remains favourable overall.

Taken together, these results suggest that glutamine could play an interesting supporting role in strategies for managing intestinal hyperpermeability.

However, the researchers stress the need for further research to confirm these long-term effects and to clarify the mechanisms involved.

Glutamine and supplementation: options for intestinal support?

These promising results mean that glutamine is now one of the most widely used amino acids in digestive support formulas.

Supplements based on pure L-glutamine

Food supplements are no substitute for medical treatment. But in certain cases – and under the supervision of a health professional – targeted supplementation can be used to support intestinal well-being.

Some formulas offer glutamine in its natural form.

L-glutamine is generally available as a powder, to be taken diluted in water or a neutral drink (outside mealtimes for better assimilation).

Discover L-Glutamine, a pure, additive-free glutamine supplement that guarantees an excellent intake of 3g of glutamine a day.

Synergistic formulas for leaky gut

Other formulas combine glutamine with other active ingredients that support the integrity of the intestinal barrier.

These complexes may include plant extracts, vitamins and trace elements, or prebiotics and probiotics.

Discover PermeaGut Formula, a complete food complex recommended for leaky gut, containing the best nutrients tested to support the integrity of the intestinal barrier (L-glutamine, L-carnosine zinc, butyrate, vitamin A, vitamin D3 and quercetin).

In the context of an overall approach (diet, stress management, medical support), glutamine supplementation is part of a strategy to maintain digestive comfort and immune balance, and could provide useful support for the intestinal barrier.