Glutamine
The most abundant amino acid in the body, the preferred fuel of gut and immune cells, and conditionally essential during intense stress or illness.
Glutamine is the most abundant amino acid in the blood and muscles. Normally, the body makes enough of it (non-essential), but in situations of intense stress (serious illness, surgery, burns, very intensive training), needs exceed production and it becomes conditionally essential.
The original angle (the fuel of the gut and of immunity): a key particularity: glutamine is the preferred fuel of fast-turnover cells
- The enterocytes (cells of the gut lining) use it heavily as an energy source and to maintain the integrity of the gut barrier. It is studied for repairing leaky gut and for digestive health
- Immune cells (lymphocytes) depend on it to multiply during an infection
This is why, under major stress, the body “raids” muscle glutamine to feed the gut and immunity. Hence the muscle wasting of serious illness and the link between overtraining, weakened immunity and digestive problems in extreme athletes.
Therapeutic and sports use: glutamine supplementation is used in medical settings (nutrition for the critically ill, gut repair). In the “normal” athlete, the evidence of a benefit for performance or recovery is modest: a sufficient protein intake supplies enough glutamine for most people. Sports marketing oversells it.
Gut health: its role in the integrity of the gut barrier makes it a supplement under study for leaky gut syndrome, inflammatory bowel disease (IBD) and recovery after gut injury, but within a supervised setting, not as routine self-medication.
Sources: meat, fish, eggs, dairy products, pulses, spinach, cabbage. A varied high-protein diet supplies it naturally.