Do athletes need glutamine?

Glutamine, taken either in the diet or as a supplement, preserves muscle function and improves nitrogen balance. In addition, it crosses the blood-brain barrier and acts as a precursor to neurotransmitters. In theory, this makes it beneficial in athletes who subject their bodies to high levels of physical and mental stress and whose requirement for glutamine far exceeds that of a non-training person. Glutamine deficiencies can contribute to sub-optimal performance and slow recovery times.

The "Glutamine Hypothesis" based on research conducted by Parry-Billings et al, provides a mechanism to explain the increased susceptibility to infection and immune system impairment common among endurance athletes.

What research supports extra glutamine?

The "Glutamine Hypothesis" based on research conducted by Parry-Billings et al, provides a mechanism to explain the increased susceptibility to infection and immune system impairment common among endurance athletes.

However, re-evaluation of this work showed that the functioning of immune system cells was only severely impaired when glutamine concentrations dropped below 100 μmol/L. Realistically, even the most over-trained athlete would never reach this value since even with severe burns, glutamine concentrations rarely drop below 200 μmol/L.

In addition, most athletes typically already consume foods high in protein as well as protein supplements, all-natural sources of glutamine. Generally, well-controlled trials have failed to show any benefit of glutamine supplementation in healthy, well-nourished people.

Trials investigating glutamine supplementation for other conditions (such as young people with cancer undergoing chemotherapy) have shown similar results - no significant difference between glutamine supplementation and no supplementation.

The bottom line is if your diet contains your recommended daily intake of protein from ANY source (plant or animal), supplementation with extra glutamine is of no benefit.

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What is glutamine?

Protein makes up 20% of the human body and consists of smaller building blocks, called amino acids. These join together in chains to make different types of protein. There are 20 different amino acids, and glutamine is the most abundant.

Glutamine helps regulate fluid levels, body temperature, and heart rate; and keeps our pH in balance. Glutamine directly influences how much protein is made, and how much is degraded. It helps our immune system to function as well as our gut.

Under normal conditions, our body makes enough glutamine to satisfy our daily needs. However, certain circumstances, such as strenuous exercise, critical illness, stress, burns, and trauma result in an increased requirement for glutamine.

If glutamine requirements exceed what the body can make, extra glutamine must be provided by the diet. Otherwise, our immune system, digestive tract, and several other vital cellular processes may suffer.

Glutamine naturally occurs in most animal and plant protein sources; meat, seafood, dairy, eggs, beans, and nuts are all high in glutamine. Glutamine is also available as a supplement, L-Glutamine.