L-glutamine is one of the 20 amino acids that build the body's proteins - a component of muscle, a neurotransmitter and a factor regulating the homeostasis of every cell in the body. The role of L-glutamine in serious diseases is crucial. Athletes are also likely to benefit from its supplementation. How does L-Glutamine work? Who should take L-glutamine and how should it be supplemented?
What is L-Glutamine?
L-glutamine is one of the 20 protein amino acids. The letter "L" before its name refers to the optical activity and optical isomerism of the amino acid. With no further structural details, it should be enough to say that the "L" form of the amino acid is biologically active, while the "D" form is the one that has no biological significance for the human and other mammalian organisms. The terms "L-glutamine" and "glutamine" are synonymous with each other.
L-glutamine is one of the conditionally essential amino acids. It means that when the amount of L-glutamine produced by the body through precursors is insufficient, it becomes a vital amino acid that must be supplied with food. The main precursor of L-glutamine is glutamic acid, which is an endogenous amino acid. Therefore, L-glutamine deficiency is associated with states of highly increased demand, e.g. during severe illness or high physical activity..
L-glutamine - role in the human body
L-glutamine is the amino acid most commonly found in the body and has very versatile functions. The roles of L-glutamine include:
- mediating the exchange of nitrogen in the form of ammonia between tissues,
- maintaining the pH balance in the body,
- synthesising nucleotides,
- participation in the synthesis of NADPH, which is the source of energy for body cells,
- participation in the synthesis of antioxidants,
- strengthening immune mechanisms, production of lymphocytes and macrophages,
- providing energy for enterocytes of the intestinal mucosa,
- prevention of intestinal mucosal atrophy and so-called leaky gut syndrome.
L-glutamine is a critical amino acid for cell homeostasis and proliferation. Without its appropriate concentration, the formation of new cells is impossible. Moreover, about 80% of the total L-glutamine content in the organism is present in skeletal muscle, while this amino acid represents between 50-60% of free amino acids in muscle tissue. The increased demand for L-glutamine is related to the fact that, under catabolic conditions, it becomes the main source of energy for many body cells instead of glucose. L-glutamine is particularly important as an energy source for immune system cells. Catabolic conditions include states of malnutrition, sepsis, recovery from burns, surgery, and physical activity with high intensity or training volume. Low levels of L-glutamine in the body can impair the function of immune cells and increase the risk of death. Currently, L-glutamine is routinely supplied to patients before or after surgical operations and to competitive athletes.
Health promoting properties of L-glutamine
L-glutamine in digestive tract diseases
L-glutamine reduces inflammation in the digestive tract, particularly in the intestines. It is recommended as an aid in the treatment of diseases such as irritable bowel syndrome, inflammatory bowel disease, Crohn's disease, ulcerative colitis, diverticulosis, diverticulitis, leaky gut or any of the problems associated with it, such as joint pain, rosacea, atopy as well as any type of autoimmune response, including the very common Hashimoto's disease nowadays. The role of L-glutamine for intestinal disease is huge, as this amino acid provides an energy source for epithelial cells and is essential for rebuilding and repairing damage to intestinal tissues. Some studies involving humans show that taking L-glutamine for leaky (leaky) gut strengthens the tight junctions between intestinal epithelial cells and prevents the symptoms associated with an autoimmune response.
L-glutamine for mental health
Conditions that increase the need for L-glutamine are not only serious physical diseases but also mental trauma and illnesses. L-glutamine is a neurotransmitter, so its deficiencies in the brain are associated with diseases such as epilepsy, bipolar disorder, schizophrenia, anxiety, depression and alcohol dependence. L-glutamine also slows down the brain's ageing process, so the need for it increases among the elderly.
L-Glutamine for athletes
Physically active people who train regularly can be very beneficial with L-glutamine supplementation. Intense, high-volume physical activity is a stressor for the body, which increases the catabolism of muscles and tendons, resulting in an increased demand for L-glutamine. Furthermore, L-Glutamine protects muscle proteins from breakdown and its use as an energy source, increases the strength of muscles during a short, intensive effort, and accelerates post-workout muscle regeneration, by increasing the hydration of muscle tissue.
By accelerating the body's detoxification from nitrogenous compounds and supporting the immune system, L-Glutamine lowers the risk of overtraining syndrome and reduces the production of stress factors associated with it.
L-glutamine - food sources
L-glutamine is widespread in both high-protein animal and plant products. It is one of the amino acids supplied in the largest amounts with food, and the average intake of L-glutamine in a protein-rich diet is 6.85 ± 2.19 g per day. Most L-glutamine is found in meat, fish, eggs, dairy, pulses, tofu, white rice, spirulina, red and or white cabbage, asparagus, or broccoli. For example, 100g of beef contains 1.2g of L-glutamine, 100g of egg or tofu contains 0.6g, and 100g of skim milk or white rice contains 0.3g.
L-glutamine supplementation is not for everyone. Experts emphasise that with normal levels of L-glutamine in the body, adequate intake with food, the absence of catabolic and disease states, taking increased portions of L-glutamine will not bring additional benefits to the immune system and muscle mass growth. However, supplementation is necessary during disease states, especially in inflammatory bowel diseases and leaky gut (autoimmune diseases can indicate this!), before and after surgery, in trauma or mental illness and for very physically active people. The intake of L-glutamine is also recommended in vegetarian and protein-restricted diets. In such cases, there is an increased risk of not getting the right amount of amino acids from food.
The doses of L-glutamine given to research participants are different depending on the condition of the patient, but the most common is 20 g per day. In sickle cell anaemia 5 to 15 g of L-glutamine is given twice a day, in weight loss due to AIDS 14-40 g a day, and in burns 25 g in equal portions every 4 hours.
Physically active people are usually recommended to take 5-10 g of L-glutamine daily. There are various ways of supplementation - in the morning, around training, only after training, in combination with BCAA or creatine. It all depends on the needs of the body, and the best way to choose a supplementation technique is to observe the body's response after its intake.