Amino acids are the basic building blocks of the body. They provide energy, like fats and carbohydrates, but they are characterized by the fact that they contain nitrogen, whereas fats and carbohydrates do not. Because of this, only amino acids are capable of forming tissues, organs, muscles, skin, and hair. Amino acids regulate almost all of the metabolic processes in the human body and are essential for health.
More than 200 different amino acids exist, but L-glutamine is the most abundant amino acid in the bloodstream and makes up 30-35 percent of the amino acid nitrogen in the blood. Glutamine was also the first to be converted to powder form, where it was used to lose weight, burn fat, and build muscle.
Though it’s still popular in the fitness community, science has shown many other benefits of L-glutamine for overall health and wellness.
1. What is glutamine?
Glutamine is an amino acid that is used as a building block for the body proteins, fuel for cells that line the gut, and fuel for immune cells, as well as to maintain nitrogen balance and prevent the burning of other amino acids for energy[8,38]. It’s also the most abundant amino acid in the body. In addition, glutamine makes up to 60 percent of the free amino acids in the bones, making it an important supplement for fitness enthusiasts.
Glutamine is not an essential amino acid, since the body does produce it. That said, our bodies need so much glutamine that our bodies may not be able to produce enough, and in those cases, it must be obtained from diet[17,27,39]. This makes glutamine a conditionally-essential amino acid. Stress, inflammation, injuries, and some bodily functions can cause the body to need more than it can produce.
2. Immune support
Lymphocytes, macrophages, and neutrophils are immune cells that require glutamine. The presence of glutamine surrounding these cells allow white them to grow. Injuries, infections, cancer treatments, and surgeries tax the immune system and deplete glutamine from the body. This can that compromise other tissues and functions that require glutamine. In addition, supplementation with glutamine can aid recovery from these events.
Studies with systemic inflammatory response syndrome patients, glutamine was shown to increase the levels of B and T lymphocytes, which reduced inflammation and improved recovery. In patients receiving bone marrow transplants, glutamine led to fewer infections, which can be a significant complication. In infants with low birth weight, glutamine supplements reduced hospital-acquired sepsis, a condition in which the body injures its own tissue in response to infection, and bacteremia, a bacterial infection of the blood[29,50].
The macrophages, lymphocytes, and connective tissues involved in wound healing require glutamine for energy. Upon injury, the surrounding tissue and cells deplete glutamine faster, which breaks down muscle cells to obtain glutamine for wound healing. Glutamine supplements not only improve healing, but also prevent lean muscle mass from being broken down.
3. Leaky gut
Millions of people suffer with leaky gut, a syndrome that causes many autoimmune diseases. A normal digestive tract keeps proteins, bacteria, and undigested food particles within the intestines, but leaky gut causes intestinal permeability that allows all these substances to leak from your intestinal wall into your bloodstream, which can trigger chronic inflammation. Symptoms of leaky gut can include bloating, food sensitivities, fatigue, joint pain, headaches, weight gain, and acne. If left unrepaired, leaky gut can contribute to thyroid disease, inflammatory bowel disease, depression, anxiety, migraines, chronic fatigue, arthritis, and skin diseases like psoriasis[24,25].
Glutamine is the major fuel source for cells of the small intestine. In studies, it’s been shown to decrease intestinal permeability, which heals leaky gut. Glutamine can cure digestive issues, such as irritable bowel syndrome, Crohn’s disease, ulcerative colitis, diverticulosis, diverticulitis, leaky gut, or any of the associated symptoms of leaky gut[6,30].
Studies have also shown that glutamine can regulate IgA immune response, which is an antibody that attacks pathogens, but is also associated with food sensitivities and allergies. It also normalizes the effects of the TH2 immune response that stimulates inflammatory cytokines. These reactions show that glutamine can help treat inflammatory conditions in the gut.
4. Energy and athleticism
One hour of exercise can cause a 40 percent reduction of glutamine in the body[26,31]. Strenuous exercise also suppresses immune function, which can have a negative effect on your physical performance and cause overtraining syndrome, a condition in which a person trains beyond the body’s ability to recover. Overtraining syndrome can result in a lack of energy, soreness, joint pain, insomnia, lowered immunity, and poor performance.
Glutamine benefits long distance athletes by boosting the immune system’s T-helper cells, which reduce the stress associated with overtraining. T-helper cells are important for adaptive immune responses, and help the activity of other immune cells by releasing T-cell cytokines, which can help suppress or regulate other immune responses.
One of glutamine’s main roles is to support detoxification. It cleanses the body of high levels of ammonia by acting as a buffer and converting excess ammonia into other amino acids, sugars, and urea. High levels of ammonia can cause impaired memory, shortened attention span, reversed sleep cycles, lack of coordination, and high blood pressure in the intracranial space. In severe cases, brain damage can occur[22,45].
During intense workouts, your body is in a state of stress, and your muscles and tendons require higher amounts of glutamine than a normal diet supplies. Following an intense workout, cellular glutamine levels can drop by 50 percent, and plasma glutamine levels can drop by 30 percent. This state creates an opportunity for your body to break down muscle to use for energy, instead of carbohydrates, which destroys all your hard work.
Glutamine prevents this from happening by pushing your muscles further, which boosts your strength and repairs skeletal muscles. Glutamine supplements promote faster recovery from intense weight training and improves muscle hydration[11,44]. Both of these factors aid in the recovery process and reduce recovery times for wounds and burns.
Glutamine can take up to five days to replenish, so it’s important to take glutamine supplements regularly if you engage in intense workouts. Overall, glutamine is beneficial for performance, metabolic, muscle recovery, and muscle building, so supplementing regularly will benefit all aspects of your fitness[23,32].
Human growth hormone (HGH) is a natural testosterone booster that your body produces on its own. HGH is important for cell regeneration, growth, and maintaining healthy tissue, all of which are important for fitness. HGH also accelerates lipolysis, which is the breakdown of lipids and triglycerides into glycerol and free fatty acids that can help you lose weight.
HGH levels are up by 400 percent following glutamine supplementation[33,34]. This hormonal response increases the resting metabolic rate and increases the after-burn effect that occurs following exercise. The afterburn effect is essential for burning fat, losing weight, and building muscle.
Glutamine also burns fat and builds muscle mass by suppressing insulin levels and stabilizing blood glucose. Because of this, less lean muscle is used to maintain blood sugar and insulin sensitivity in the cells. Glutamine’s effect on insulin and blood sugar can also be beneficial for diabetics and individuals who suffer from sugar cravings[13,19].
7. Peripheral neuropathy
Peripheral neuropathy is a condition in which the peripheral nerves are damaged. Peripheral nerves are apart from the brain and spinal cord, but send information from other parts of the body to the brain. There are three types of peripheral nerves: motor nerves, sensory nerves, and autonomic nerves. Motor nerves control skeletal muscle, sensory nerves transmit information from the senses, and autonomic nerves control involuntary processes, such as breathing, digestion, heart function, and gland function. Symptoms include cramps, muscle weakness, numbness, tingling, irregular heartbeat, and severe pain.
Chemicals used during chemotherapy interfere with different aspects of cell division in cancer cells. Many cancer patients who undergo chemotherapy experience some degree of neuropathy, usually motor neuropathy or sensory neuropathy, which can be so devastating that they require lower doses, or stop altogether, which can limit their survival.
Glutamine benefits the immune system, repairs damaged cells and tissues, and aids in recovery, as well as supporting the function of vital organs. Glutamine may be effective in preventing or reducing the severity of peripheral neuropathy during chemotherapy treatment. Patients on 10 grams of L-glutamine three times a day experienced less-severe instances of neuropathy, as well as a reduction in numbness and muscle weakness[15,51].
Anxiety disorders can affect your well-being and ability to function normally in society. Many drugs exist to improve anxiety symptoms, but dietary supplements, like glutamine, can provide benefits.
Glutamine is the precursor to GABA, or gamma-aminobutyric acid, the primary inhibitory neurotransmitter in your brain. This gives it a calming effect on your nervous system. GABA can decrease the number of anxiety-related messages in your brain by inhibiting neuron firing. Glutamine can lessen the symptoms of anxiety, which include fatigue, irritability, tension, mood changes, sleep problems, and cognitive difficulties, by increasing GABA productions.
In studies, glutamine was found to significantly improve all measured mood symptoms in anxiety patients, as well as depression, tension, fatigue, and confusion.
9. Maintains branched-chain amino acid levels
Following injury or stress-induced muscle wasting, glutamine levels become depleted in the muscles. In addition, glucocorticoids, a type of steroid, can trigger muscle waste in healthy individuals, which further depletes glutamine levels.
When glutamine depletes, so do the levels of branched-chain amino acids. Branched-chain amino acids are essential amino acids that play a vital role in protein synthesis. When glutamine levels decrease. leucine decreases by 23 percent, valine by 27 percent, and isoleucine by 33 percent. The oxidation of leucine was directly related to decreased glutamine levels.
Studies have shown that steady glutamine levels in the blood decrease leucine oxidation in adults, infants, and children with Duchenne muscular dystrophy, a condition in which abnormal genes lead to muscular degeneration and muscle weakness.
10. Heart protection
Heart surgeries can produce an injury to the heart, ischemia/reperfusion. Ischemia is due to low oxygen levels, while reperfusion is the return of oxygen after low oxygen levels. Ischemia/reperfusion injuries lead to elevated levels of troponin I, creatine kinase-MB, and myoglobin. Increased levels of these proteins have been linked to increased death and morbidity.
In studies conducted on patients who have undergone heart surgery, those who took glutamine supplements showed decreased levels of troponin I and creatine kinase-MB at 24 and 48 hours. Myoglobin decreased after 24 hours. The lower levels of these proteins led to fewer heart injuries and fewer complications.
In addition, cells that had undergone ischemia/reperfusion were given glutamine, and less glutamine-fed cells were killed as a result. The contractile function of the heart cells was recovered in all glutamine-fed cells, while none of the non-glutamine fed cells were able to recover that function.
11. Foods high in glutamine
Glutamine is synthesized from glutamic acid and glutamate, so if your body can’t produce enough, it needs to be obtained from the diet. Glutamine is usually found in animal food sources, such as meat and dairy, and some plant-based proteins, such as beans, spinach, parsley, and red cabbage.
The foods with the highest levels of glutamine are bone broth, grass-fed beef, spirulina, Chinese cabbage, cottage cheese, asparagus, broccoli raab, wild-caught fish, such as tuna, cod, and salmon, venison, and turkey[5,50].
Food sources of glutamine are superior to glutamine supplements, because natural sources of glutamine are unlikely to build up within the body, and long-term supplementation with glutamine can impair the body’s own ability to produce and absorb glutamine. To be sure you’re getting enough glutamine to benefit from it, eat at least three glutamine-rich food sources per day.
12. Glutamine supplements
Since many people don’t get enough glutamine from their diet, supplementing with glutamine can boost your immune system and improve your ability to fight off illness. Since 60 percent of your skeletal muscle is made of glutamine, supplementing can also aid in protein synthesis and balance pH levels[16,37,42].
Glutamine supplements come in two forms. Normal L-glutamine in its free form should be taken with food for proper absorption. Trans-Alanyl or Alanyl-L-Glutamine, which is an amino acid attached to another amino acid, is easier to digest and can be taken on an empty stomach[14,43,48]. Both forms should be taken immediately following a workout to best support your metabolism and weight loss, as well as for building muscle, preserving lean mass, and aiding recovery. In addition, glutamine supplements should be taken during periods of physical trauma and stress to maintain glutamine concentrations.
The usual dosage of glutamine is between 2 to 5 grams, twice daily, and up to 10 grams daily for serious athletes[2,46,52]. Excess glutamine rarely causes problems, but it’s best to supplement with B-complex vitamins, especially B12, to control glutamine buildup in the body.
13. Side effects
Glutamine is naturally-occurring and generally safe, but it does have a few side effects. Different amino acids can compete with each other for transport and absorption into the gut and kidneys, and glutamine supplements can increase glutamine concentrations to the point where other amino acid transport and absorption suffer. In addition, excessive glutamine supplementation can impair your body’s own ability to produce glutamine, which can lead to the production of glutamate and ammonia[1,3,12].
Glutamine supplementation can also impair the body’s ability to detoxify harmful molecules, like ammonia. Excessive supplementation with lead to decreased transport of ammonia by glutamine over time. Other side effects include damage to the immune system, increased risk of cancer, tumor growth, and increased levels of other amino acids in the blood, which can lead to acidic conditions[9,10,18].
Though rare, glutamine is contraindicated with certain cancer drugs, like irinotecan/5-fluorouracil. In addition, glutamine and omega-3 fatty acids produce similar, beneficial effects in cancer patients. When combined with omega-3 fatty acids, however, glutamine and omega-3s cancel out each other’s cancer- fighting benefits, and the treatment results were worse. Regardless of your individual goals, it’s best to speak to your doctor about supplementing with glutamine.
The sati line
Because glutamine is the most abundant amino acid in the body, low levels of glutamine can negatively impact your gastrointestinal system, energy levels, and immune system. While it’s unlikely to experience an actual deficiency, since your body produces its own, glutamine is used for so many different processes that it’s important to maintain optimal levels.
Glutamine benefits include healing ulcers and leaky gut, rebuilding and repairing intestines, increases mucus production in the gut, promotes muscle growth and preserves lean mass, improves athletic performance and recovery, improves metabolism and cellular detoxification, curbs cravings for sugar, fights cancer, and improves blood sugar levels. Glutamine is readily available in animal protein sources and some plant-based sources, so a whole, balanced diet will ensure that you are likely to get all the glutamine you need from your diet. For individuals who require additional glutamine, due to illness or strenuous exercise, many glutamine supplements are available, but since they can affect your body’s own production of glutamine, it’s best to get glutamine from food.
Whether you’re looking to increase your athletic performance or improve your overall health, L-glutamine is an important part of your daily diet.
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