Health Benefits of L-Glutamine

Sports supplement may improve gut health and wound healing

Female runner in park
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L-glutamine is one of two forms of the amino acid glutamine. Produced mainly in the muscles, L-glutamine plays a key role in many biological processes, including the synthesis of protein, the regulation of kidney and immune function, and the maintenance and repair of intestinal tissues. (Its counterpart, D-glutamine, appear to be of lesser consequence to human function.)

L-glutamine also serves as a secondary fuel source for cellular energy and helps create other important compounds, including glucose and purines (the building blocks of DNA).

It is believed that by supplementing the body's natural reserves of L-glutamine, many of these biological functions can be enhanced. L-glutamine is also used by athletes and bodybuilders to build muscle mass and speed exercise recovery.

L-glutamine should not be confused with L-glutathione, the supplement form of glutathione that is believed to have potent antioxidant properties.

As opposed to the glutamine naturally produced by the body, L-glutamine is synthesized in the lab from either animal proteins or fermented vegetable-based compounds.

Health Benefits

Alternative practitioners have ascribed L-glutamine with a multitude of health benefits, including the treatment of anxiety, bipolar disorder, Crohn's disease, depression, epilepsy, insomnia, irritable bowel syndrome, obesity, peptic ulcers, schizophrenia, and ulcerative colitis.

L-glutamine is also occasionally used to alleviate some of the side effects of chemotherapy or to promote healing in people with serious burns.

As is often the case with dietary supplements, many of these claims are unsubstantiated or exaggerated. With that being said, there is some evidence supporting the use of L-glutamine for health purposes.

Trauma Recovery

One of the most common indications for L-glutamine use is severe trauma. It is believed that by stimulating protein synthesis and enhancing immune function, the body may be better equipped to recover from severe traumas or surgeries.

Glutamine is considered to be a prime nutrient for critically ill patients, particularly those with severe burns. When delivered intravenously (into a vein) or via enteral tube feeding, L-glutamine appears to improve wound healing while preventing the spread of bacteria from the wound site to the bloodstream.

This may be especially useful for people undergoing bone marrow transplants or other types of transplant in which the immune system is deliberately suppressed.

Among burn patients, a 2009 study from India reported that the enteral delivery of L-glutamine reduced bacterial complications as well as hospital stays by almost 17 days compared to a control group.

Athletic Performance

There is little scientific evidence to support the claim that L-glutamine supplements are beneficial to athletes, says a 2008 review published in the Journal of Nutrition. Typically used to shorten recovery time following high-intensity exercise, L-glutamine has yet to provide any evidence of this in clinical trials.

Even at doses of 20 to 30 grams, L-glutamine neither enhanced metabolism (as measured by glycogen synthesis) nor reduced catabolism (the breakdown of muscle) following extreme exercise.

To date, few clinical trials have looked at the effects of L-glutamine supplements on sports performance. Of these, a small study published in the Journal of Sports Medicine and Physical Fitness found that L-glutamine failed to enhance high-intensity exercise performance in a group of 10 male athletes.

Chemotherapy Side Effects

A number of studies have suggested that L-glutamine may be useful in alleviating some of the dermatological side effects of cancer therapy.

According to a 2017 study in Molecular and Clinical Oncology, L-glutamine reduced the incidence and severity of skin inflammation (treatment-induced dermatitis) in people undergoing chemo or radiation therapy.

Of the 50 people recruited for the study, those provided 10 milligrams of L-glutamine three times daily had less overt dermatitis than those provided a placebo. However, the supplement did nothing to alter the pain levels associated with the condition.

Moreover, the incidence of mucositis (inflammation of the digestive tract, including the mouth) was not altered by L-glutamine as has long been suspected.

With that being said, a 2007 study in Colorectal Disease found that L-glutamine decreased post-operative complications and reduced the duration of hospital stays in people who had undergone colorectal cancer surgery.

Further research is needed to determine L-glutamine's appropriate application in cancer treatment.

Possible Side Effects

As the most abundant amino acid in the human body, L-glutamine has long been presumed to be safe as a dietary supplement. Even at higher doses, L-glutamine does not appear to cause significant side effects.

With that said, there have been few studies investigating the long-term effects of L-glutamine supplements or at which doses L-glutamine may cause toxicity.

There is evidence, albeit slight, that L-glutamine supplements may trigger seizures in people on anticonvulsant medications. Because L-glutamine is metabolized by the liver, it may need to be avoided in people with severe liver disease.

Due to the lack of safety research, it is best to avoid L-glutamine during pregnancy or in breastfeeding mothers. While L-glutamine has been used safely is children, it should only be prescribed under the supervision of a pediatrician.

Dosage and Preparation

Generally speaking, you would expect to obtain between 3 to 6 grams of L-glutamine through the foods you eat each day. L-glutamine supplements taken within this range are considered safe for daily use.

The observed safe level for supplemental L-glutamine in healthy adults is 14 grams per day, according to a 2008 report in Regulatory Toxicology and Pharmacology. Children are generally dosed at no more than 0.7 grams per kilogram of body weight per day (g/kg/day).

L-glutamine is readily found online or in health food stores, pharmacies, and shops specializing in dietary supplements. The supplements are most commonly sold in capsule or powder forms.

What to Look For

As dietary supplements are largely unregulated in the United States, opt for brands that have been voluntarily submitted for inspection by an independent certifying body like the U.S. Pharmacopeia (USP), ConsumerLab, or NSF International. In this way, you can be better assured of the product's quality and safety.

If you are vegan or vegetarian, look for L-glutamine supplements made from fermented plant-based materials (usually beets).

Other Questions

Can I get enough L-glutamine from food?

Despite what many bodybuilding websites will tell you, you can get ample supplies of L-glutamine from food. In the end, L-glutamine has not been considered an essential nutrient because your body can produce all that it needs on its own.

So don't be misled by claims that you can benefit from L-glutamine supplements. Glutamine deficiency rarely occurs outside congenital disorders like Kegg's disease, which affects less than one out of every 100,000 births.

Among some of the food highest in L-glutamine are:

  • Beef: 1.2 grams per 4-ounce serving
  • Eggs: 0.6 grams per two eggs
  • Tofu: 0.6 grams per 3.5-ounce serving
  • Corn: 0.4 grams per half-cup serving
  • Milk: 0.3 grams per half-cup serving
  • White rice: 0.3 grams per half-cup serving
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