L-glutamine is the most abundant free amino acid in the body. It is involved in protein synthesis, cell renewal and energy production in fast-renewing cells such as enterocytes (intestinal lining cells) and lymphocytes (immune cells). During intense physical effort, prolonged stress or dietary imbalance, glutamine reserves can drop significantly — a decline that directly affects gut lining permeability, muscle recovery capacity and immune response. Supplementation helps maintain optimal levels and support the body through periods of increased demand, which is of particular interest to athletes, people focused on digestive comfort, and those going through periods of fatigue.

A number of scientific publications highlight L-glutamine’s role in maintaining the integrity of the intestinal barrier: as the preferred energy substrate of enterocytes, it supports the tight junctions between cells lining the gut wall, helping limit the passage of unwanted molecules through the mucosa — sometimes referred to as intestinal permeability. For sports recovery, glutamine takes part in muscle glycogen resynthesis and helps reduce protein breakdown after exercise. It is also a precursor to glutathione, one of the body’s main internal antioxidants, and to GABA, a neurotransmitter involved in relaxation and stress management — making it a versatile amino acid, useful well beyond sport.

The Kyowa Quality certification is an internationally recognised mark of excellence. Kyowa Hakko, the Japanese manufacturer behind this standard, has produced L-glutamine through plant-based biofermentation for decades, using natural micro-organisms grown on a plant substrate, without chemical solvents or animal extraction, to achieve a purity above 99%. Every batch is tested to ISO 9001 standards and international pharmacopoeias (USP, EP), with HPLC analysis confirming the absence of contaminants, heavy metals and solvent residues — a level of rigour well above synthetic glutamine or less controlled processes commonly found on the market.

Immune cells, particularly lymphocytes and macrophages, use glutamine as their primary energy source, and demand for it rises considerably during periods of physical or psychological stress; when reserves run low, the body’s ability to mount an effective immune response can be reduced, so supplementation can help support this function, especially in athletes undergoing intensive training. L-glutamine is also a direct precursor to glutathione, considered the body’s major intracellular antioxidant, which neutralises free radicals, protects cell membranes and supports liver detoxification — by supplying the substrate needed for its synthesis, glutamine indirectly helps the body’s daily defence against oxidative stress.

Take 1 to 4 capsules a day with a large glass of water, ideally with meals; for digestive support, taking it on an empty stomach in the morning can also be considered. A course of 4 to 8 weeks is recommended, repeatable after a 2-week break. For regular athletes, dosage can be adjusted to training intensity and individual needs.

For adults only. Do not exceed the recommended daily dose. Not recommended for pregnant or breastfeeding women without medical advice. If taking medication, consult a healthcare professional before use. Food supplements should not replace a varied, balanced diet and a healthy lifestyle. Store in a cool, dry place away from light. Keep out of reach of young children.

What is L-Glutamine used for?

L-Glutamine is an amino acid involved in protein synthesis, maintaining the intestinal barrier, producing glutathione (a major antioxidant) and supporting immune cells. It is particularly called upon during intense physical exertion or periods of stress.

What is the difference between L-Glutamine and glutamine?

L-Glutamine refers to the levorotatory form, the form naturally present and biologically active in the body — the form used in quality food supplements. The Kyowa Quality mark confirms it is genuinely pure, plant-fermented L-Glutamine.

Can L-Glutamine be taken every day?

Yes — it can be taken daily as part of a 4 to 8 week course. Follow the recommended dose and check with a healthcare professional if in doubt, particularly if taking other medication.

How should I choose an L-Glutamine supplement?

Look for one made through plant-based biofermentation, free from excipients and additives, with a recognised certification such as Kyowa Quality. Capsules made from pullulan (a plant material) suit those wanting a fully plant-based, clean-label product.

Herba Barona is an independent specialist supplement shop in the heart of Paris — established in 2006. What you order is genuinely on our shelves: we ship from our own stock, with no dropshipping and no long waits.

Visit us at 10 rue Théophile Roussel, Paris 12 — or use Click & Collect and pick up your order in-store. We also deliver across France and Europe. Friendly, expert advice in English from our team.

Where is the shop?

Herba Barona is at 10 rue Théophile Roussel, 75012 Paris — a two-minute walk from Ledru-Rollin (line 8), close to Bastille. Open Tuesday to Saturday, 9:30 am–6:30 pm.

Can I order online or collect in store?

Yes. We ship across France and Europe under the same conditions as our French store, or choose Click & Collect to pick up your order for free at our Paris shop.