Glutamine is an amino acid that is quite popular as a sports supplement. Although glutamine is naturally produced in our muscles, including glutamine supplements in your diet is beneficial when the body cannot make enough amounts of this amino acid, such as during extensive training sessions or while recovering from injuries.
Glutamine is also growing in demand as a weight loss supplement as this seems to reduce food cravings and steady blood sugar. Another advantage of having adequate glutamine in your body is that it helps maintain muscle mass during weight loss. You’re better able to lose weight while maintaining muscle mass. This amino acid has been found to help reduce, and even eliminate, cravings by helping to steady blood sugar.
What Is Glutamine?
Glutamine is an amino acid, one of the building blocks of protein that helps in transporting substances through the blood and fights off bad bacteria and viruses. Protein helps the body to build and maintain muscles. Glutamine contributes to about 60% of the skeletal muscle amino acid pool. It plays a crucial role in our immunity, protein synthesis, and in maintaining the health of our intestines.
There are two types of glutamine, L and D types that vary only in their molecular arrangements. Since L-Glutamine is the most common amino acid produced in muscles, the relationship between glutamine and healthy muscles gained importance and studies have been undertaken from time to time.
Glutamine is a vital forerunner to the structuring of DNA and RNA and speedily dividing cells require more of this amino acid. Though the body produces glutamine for essential functions, in certain conditions this quantity becomes inadequate. A glutamine food source or supplement fills this need. In the 1990s a report published by Women’s Hospital, Boston mentioned that
“During stress, the body’s requirements for glutamine appear to exceed the individual’s ability to produce sufficient amounts of this amino acid”
The Mechanism of Glutamine
Neurotransmitter levels are often limited by the availability of the amino acids required to create them. The most abundant neurotransmitter in our central nervous system and brain, glutamate is converted from glutamine by the enzyme glutaminase.
Glutamine can pass the blood-brain barrier, unlike glutamate. Glutamine is converted to the neurotransmitter GABA (gamma-aminobutyric acid) in the brain. Oral supplementation of L-Glutamine has been found to increase GABA levels. As a neurotransmitter. GABA regulates communication between brain cells. GABA has many roles in the human body including the regulation of muscle tone. GABA reduces anxiety and calms your mood by inhibiting neural activity and this promotes better sleep.
About 90% of glutamine is manufactured in the muscles and is then transported through the blood to the organs that require this amino acid. It also provides fuel (nitrogen and carbon) to cells of the body. Post-surgery and trauma injury recoveries require nitrogen to repair cells and for the continuous function of the vital organs. One-third of this nitrogen is obtained from glutamine.
Glutamine also helps in making other amino acids and glucose. Taking glutamine supplements helps prevent the depletion of this amino acid, especially for people suffering from HIV or AIDS. Tissues affected by chemotherapy treatment benefit from glutamine supplements that prevent damage. Small amounts of glutamine are produced by the lungs and brain. A 2011 study from South Korea observed that glutamine supplements are beneficial in patients with a surgical and critical illness.
Natural Food Sources of Glutamine
Glutamine is found naturally in plants and animal products. Animal sources provide glutamine in large amounts due to their high protein content. Chicken, fish, beef, eggs, dairy products are good sources of this amino acid. Vegetables like beans, beets, cabbage, spinach, carrots, parsley contain glutamine.
Wheat, papaya, brussels sprouts, celery, kale and fermented foods like miso also provide glutamine. The amounts of glutamine present in these foods vary. The content of glutamine in white rice and corn is high though the total protein in them is low.
The best glutamine food sources are wild-caught fish, broccoli-rabe, grass-fed beef, spirulina, Chinese cabbage, turkey and bone broth. Listed below are some foods and their corresponding glutamine levels per 100 grams of the food item:
- Beef has 1.2 grams (4.8%)
- Skimmed milk has 0.3 grams (8.1%)
- Eggs have 0.6 grams (4.4%)
- White rice has 0.3 grams (1.1%)
- Tofu has 0.6 grams (9.1%)
- Corn has 0.4 grams (16.2%)
Further studies are yet to be conducted to determine the exact amounts present in many other food sources. As they are present in proteins, getting sufficient protein in our diet ensures this amino acid is also adequately consumed.
7 Scientifically Supported Benefits of L-Glutamine
1. L-Glutamine Reduces Muscle Soreness
Many bodybuilders use glutamine to reduce soreness after extensive training sessions. Scientific experts believe that nitrogen levels in the body are in check because of glutamine. Glutamine provides nearly 35% of nitrogen for protein synthesis. Nitrogen also helps in preventing muscle breakdown.
A 2015 study aimed to explore the use of glutamine to reduce muscle soreness after an abnormally high exercise routine. Sixteen healthy participants were chosen. The ratings were calculated for a post-exercise 72-hour period. The observation of the study was that there was a quicker recovery of peak torque and reduced muscle soreness after the unconventionally extreme exercise session.
Summary: L-Glutamine reduces muscle soreness after intense and extensive exercise sessions.
2. L-Glutamine May Benefit the Immune System
Intense exercising routines cause stress which, in turn, actually reduces your immunity. While short-duration exercise sessions, for less than an hour, may spike the amounts of glutamine in the muscles, the intensive training programs commonly followed by endurance athletes cause a drastic reduction in their glutamine levels.
Fatigue is another aspect experienced by overtrained athletes due to low glutamine in them. A study conducted in the 1990s concluded that a decrease in plasma glutamine may contribute to immune deficiency in these situations.
Some evidence points to the opinion that the immune system is less capable of defending any infection after a demanding exercise. This may be due to immunosuppression that occurs. In the late 90s, an experiment was conducted with 200 athletes, both runners, and rowers, who undertook strenuous training. They participated in different exercises. They were divided into two groups.
The first group was given glutamine and the second group was given a placebo. The athletes completed a questionnaire during the 7 days following their exercise. It was found that the first group reported a lesser percentage of infections than the second one.
Immunodeficiency virus infection causes loss of body cell mass that leads to muscle wasting. This is directly related to the period of survival. An investigation of the anabolic role of glutamine and antioxidants was conducted in 26 patients in the late 90’s. The evaluation concluded that glutamine antioxidant nutrition can increase body weight and is effective in the rehabilitation of HIV positive patients suffering from weight loss.
Summary: Drastic reduction in glutamine levels of endurance athletes causes fatigue and also reduces their immunity. Supplementing with glutamine has been found to boost their immune system and reduce the number of infections contracted.
3. L-Glutamine May Increase Exercise Endurance
Another reason why L-Glutamine is popular among bodybuilders is that it is believed to boost endurance. While working out, endurance boosters help us exercise harder and for longer. Considering that L-glutamine may increase endurance during workouts and reduces muscle soreness after a workout, it is surely tempting for those wanting to build a strong physique and bulging muscles.
Intense endurance training causes muscle breakdown and brings about an increase in blood ammonia, leading to muscle fatigue and tiredness. A 2007 study conducted in Brazil evaluated the impact of glutamine supplementation in high-level runners. On four occasions, 15 men in pre-competitive training ran for 120 minutes over a distance of approximately 34 km. The first time, they were not given any supplements before their run. On the other 3 occasions, their diets were supplemented with either carbohydrate or glutamine or a combination of both.
Blood ammonia tests were conducted before they started and at every half hour during the training. Though ammonia levels remained similar for the first hour of the training on all occasions, in the second hour it was lower than on the first occasion. The researchers concluded that:
“Supplementation in high-level endurance athletes reduced the accumulation of blood ammonia during prolonged, strenuous exercise in a field situation.”
Summary: Glutamine supplementation may boost endurance as this reduces accumulation of blood ammonia levels during prolonged exercise sessions,
4. L-Glutamine Supplementation May Improve Intestinal Health
Glutamine is used by many organs including muscles, kidneys, liver, and small intestine. This amino acid plays an important role in the health of the intestine. During illness, the demand for glutamine is increased as the immune system is continuously utilized. Nutritional depletion can lead to a decrease in muscle mass and this may decrease glutamine production capacity. Low levels of glutamine may result in the deterioration of the gut barrier whose primary function is preventing the migration of food particles or bacteria from the intestine into the blood circulation.
Thus a lack of glutamine may result in a condition called ‘leaky gut’ The intestinal wall controls what can be transported to the organs. The permeability of the intestinal wall allows nutrients to pass through and blocks toxins. When the tight junctions of these intestinal walls loosen bacteria and harmful substances enter the bloodstream. The symptoms of leaky gut include food sensitivity, digestive disorders, fatigue, and inflammation.
L-glutamine helps people with IBS by working to protect the mucous membrane of the esophagus and intestines. The mucous membrane blocks bacterial infiltration during digestion. People with stress-related IBS may also find that increasing their intake of L-glutamine reduces symptoms. This benefit is due to the body releasing cortisol when it is stressed, which can lower the levels of L-glutamine stored in the muscle tissue.
Summary: L-glutamine supplementation may help protect the mucous membrane of the esophagus and intestines and help prevent ‘leaky gut’.
5. L-Glutamine May Promote Weight Loss
A study conducted in 2014 and made known in the ‘European Journal of Clinical Nutrition’ noted that overweight women who took glutamine supplements for four weeks had lost weight despite not changing their exercise routine and food intake. Taking just a protein supplement did not create such changes in body weight. Waist measurement and body weight showed a noteworthy reduction after the intake of glutamine supplements. Further studies in this direction would determine the standard dosage required for the benefit of weight loss.
An experiment that was undertaken by 9 healthy participants wherein 2 grams of glutamine was dissolved in a cola drink and ingested for 20 minutes 45 minutes after taking breakfast. The objective of the study was to determine if human growth hormones would increase with glutamine.
Blood samples taken at 30-minute intervals for 90 minutes showed raised plasma growth hormones. The presence of high growth hormones will raise the metabolic rate and upgraded the afterburn effect. This process plays an important role in weight loss and lean muscle mass building. By helping to suppress insulin and maintain a balanced blood glucose level, glutamine supports lean muscle mass building.
Summary: L-Glutamine intake increases HGH and boosts metabolism. It also seems to promote weight loss by suppressing food cravings and helping regulate blood sugar levels.
6. L-Glutamine and Cardiovascular Health
In 2015 a study was undertaken to ascertain the long term effects of glutamine on the risk factors of cardiovascular disease among type-2 diabetic patients. 66 patients in the age range of 18 years to 65 years received 30 grams of glutamine powder or a placebo three times a day for a 6-week period.
The study showed a noted difference in body fat, waist circumference, and an appreciable increase in fat-free mass. Fasting blood sugar levels were reduced. It showed a distinct improvement in cardiovascular risk factors and the composition of the body. This evidence warrants further scope for research and study in the effects of glutamine.
GLP-1 (glucagon-like peptide) and GIP (glucose-dependent insulinotropic polypeptide) are hormones that are secreted by the small intestine. They regulate insulin produced in the pancreas. A study that was conducted in 2009 to establish if glutamine increased these hormones. The study involved 8 lean healthy subjects, 8 overweight individuals with type-2 diabetes and 8 obese participants who did not have type-2 diabetes. On three different days, oral glucose (75 grams) and glutamine (30 grams) were given. GLP-1 and GIP concentrations along with glucose and glucagon were measured over two hours.
It was found that Glutamine affected the increase of GLP-1 GIP and insulin secretion and will likely provide a new perspective in raising insulin secretion in treating obesity and type-2 diabetes.
Glutamine also supports liver health. The investigation of rodents showed a fatty liver when glutamine was excluded. While another group of rodents exhibited 47% less fat. More studies and clinical testing on humans are required for the standardization of this supplement to treat liver ailments.
Summary: Researchers have found that diabetic patients supplemented with L-glutamine showed distinct improvement in cardiovascular risk factors.
7. Glutamine Supplementation May Reduce In-Hospital Mortality Rates
For critically ill patients the demand for glutamine may exceed the stores available in the muscles. A less able immune condition can increase the cost of care and may cause fatalities.
An investigation in 2013 indicated that glutamine supplementation can be linked to a reduction of in-hospital mortality rates, especially in burn patients who suffer from complications due to gram-negative bacteremia. Further trials are necessary to record the clinical importance of glutamine.
Intravenous administration of glutamine has beneficial effects on maintaining the glutathione levels in plasma and RBC and antioxidant capabilities in post abdominal surgery periods of patients. It has shown a trend in reducing the incidence of infection with shorter hospital stays.
Summary: Glutamine supplementation has been associated with shorter hospital stays and a reduction in the incidence of infections.
The Dosage of Glutamine Supplements
Considering the fact that glutamine is a naturally produced amino acid; supplementing with it is definitely not harmful in normal amounts. The general recommendation of this amino acid is 3 to 6 grams a day, depending upon the diet being followed. A variety of doses are available from various brands, ranging from 5 grams a day, to high doses of 45 grams a day.
Glutamine powder should be taken orally with a meal or snack unless otherwise advised by a physician. It can be dissolved in 8 ounces of hot or cold beverage or mixed with soft foods. The food/drink should be consumed immediately after mixing. If you are taking supplement pills, rather than the powder version, they can be taken at least an hour before meals or two hours after meals.
Short term use of glutamine supplements is considered safe although more studies are necessary to determine its effects over long periods. Unless advised by a doctor to take a higher dose, the normal instructions given on the supplement package should be followed.
If you are a beginner, it’s best to start with a conservative amount of 5 grams a day to how your body reacts to it. Many pre-workout and post-workout supplements contain glutamine and therefore the calculation of the total quantity ingested per day is important, before adding on another glutamine supplement. The effects of plant-based glutamine may vary from a high-protein supplement that is animal-based.
The Side Effects of Glutamine Supplements
Glutamine supplementation may cause minor side effects such as vomiting, dizziness, headaches and a feeling of tiredness. It is believed that the short term ingestion of this supplement does not cause any adverse side effects. With scientists raising concern over glutamine long term use, more studies have to be undertaken. Some concerns include whether any alteration may occur in the transportation of amino acids.
Pregnant women and breast-feeding mothers should not use this supplement without a doctor’s advice. Supplementation with this amino acid also requires a doctor’s consultation if you are taking any medications. This is especially important for people having kidney or liver diseases.
Frequently Asked Questions
What is the use of L-Glutamine?
Though L-Glutamine is an important component in bodybuilding supplements, it also has many other functions in our body. It is indispensable in maintaining immunity and for the normal functions of the intestine.
Glutamine is transported via the bloodstream to the kidney, liver and small intestine and to the cells of the immune system. The white blood cells require glutamine for immune functions. Some of the signs of glutamine insufficiency are loss of muscle mass and illness recurrences.
Does Glutamine Supplementation Help Bodybuilders?
Catabolism is the break down of muscle mass that frequently occurs during bodybuilding. The anti-catabolic properties of glutamine prevent muscle breakdown. This amino acid plays a key role in the biochemical processes of protein synthesis and the fluid content within the cells. This is beneficial for people trying to get rid of body fat without losing muscle mass.
Depletion of glutamine takes place during workouts and bodybuilders are prone to illness. It could take a number of days before a natural replenishment of this amino acid is achieved. L-Glutamine is important for balancing its levels during workouts. This supplement aids in quick recovery after strenuous training. The whole body requires glutamine for high-grade performance.
Does L-Glutamine Reduce Bloating?
L-Glutamine has the capability to absorb water and salt into the cells of the muscle. A well-hydrated muscle helps in protein synthesis and cell volume. The anabolic benefit of glutamine boosts the immune system function.
Prescription for people suffering from irritable bowel syndrome and celiac disease contain glutamine as it heals the intestinal linings and reduces bloating. Glutamine restores and repairs the digestive tract of the body.
Can You Take Too Much L-Glutamine?
L-glutamine supplements are safe in low doses and for short durations. You don’t have to worry about overdosing as long as you stick to the recommended doses given your product label. There are brands that offer 3 grams of doses to 45 grams per day.
If you’re allergic to L-glutamine, side effects such as vomiting and nausea can occur. Some people have reported joint pain and hives after using glutamine supplements. Discontinue use if you experience any unpleasantness. You can start again at lower doses after consulting a physician.
The Bottom Line
Glutamine is an amino acid naturally produced in the body. It is required for the optimal functioning of our immune system and is beneficial to our intestinal health as well. Under conditions of stress and severe illness, our body resources may be inadequate to sustain immunity. An appropriate dosage of glutamine supplements can benefit health and recovery.
Glutamine supplements are popular as a sports supplement. Glutamine supplementation also benefits endurance athletes and bodybuilders whose glutamine stores may get depleted during intense and prolonged workouts. Short courses of this amino acid are not harmful. However, the effects of its prolonged use have not been researched yet.