Benefits & Side Effects of Glutamine

Amino acids are building blocks of protein, and glutamine is the most abundant amino acid found in the muscle and blood. While essential amino acids cannot be made by the body and must be consumed in the diet, glutamine is considered conditionally essential -- because a healthy, unstressed body produces adequate amounts. However, the demand for glutamine may exceed the supply in critical illness, traumatic injury or conditions that cause significant muscle loss, making glutamine essential in these situations. Glutamine is postulated to provide benefits to weight, exercise recovery and bowel disorders, but more research is needed to understand its role in these conditions. Glutamine may also have side effects, and should not be used if you have certain medical conditions, so seek medical advice before using.

Glutamine has a variety of functions in the body. It helps repair and build muscle, it helps fuel the cells that line the intestines and is an important component of the body’s immune response. These benefits can help speed healing of burns, open sores and injuries and reduce the risk of infection after surgery. When the body is under severe physical stress -- such as severe burns, traumatic injury or a severe infection -- it consumes more glutamine than the body can make from muscle stores. Without additional glutamine from supplementation or diet sources such as meat, milk, chicken or eggs, consequences include poor wound healing, higher infection risk, longer hospital stays and declining health.

In critical care units, burn centers or trauma medical centers, the supplementation of glutamine may be given to complement medical care. This amino acid may be given enterally -- by feeding tube, pills, liquid nutrition supplements, or by increasing protein in the diet. Supplementation may also be via parenteral nutrition, which is when nutrition is infused into a vein. A review article published in the April 2014 issue of “Critical Care” linked parenteral glutamine supplementation to improved survival while in the hospital, decreased length of hospital stay and a lower rate of infectious complications. However, an article published in the August 2015 issue of “Critical Care” reviewed research related to enteral glutamine supplementation, and did not find the same benefits. While the hospital length of stay was reduced, and death rates were lower in people being treated for severe burns, this review did not find that enteral glutamine provided a significant benefit in reducing infections or complication risk in those in critical care or trauma units.

Glutamine supplementation has been linked to promoting the gain of muscle and lean body tissue in people with cancer, according to an article published in the April 2002 “The American Journal of Surgery.” In addition, small and preliminary studies suggest glutamine may help with the loss of body fat in overweight people. For example, an article in the January 2015 issue of “Nutrition” showed 6 weeks of glutamine supplementation promoted loss of inches in the abdomen and an increase in lean body tissue. However, more research is needed to clearly understand glutamine’s role in weight management.

Your immune system is like a fancy car in a way -- it constantly needs high-quality fuel to run properly, and glutamine plays a major role in the fueling process. In addition to its actions on improving immune function and maintaining healthy cells in the gastrointestinal tract, glutamine is also linked to reduced inflammation, which may play a role in the management of conditions such as inflammatory bowel disease or irritable bowel disease. More research is needed to determine risks and benefits of glutamine supplementation in these conditions. Many athletes take glutamine because excessive exercise depletes glutamine stores, and glutamine supplements are thought to hasten recovery times, prevent muscle wasting and make it easier to build and maintain muscle mass. However, these benefits have not yet been proven by quality research.

Hospitals, burn centers and critical care units are more likely to use glutamine for its evidence-based benefits, so supplementation may be integrated into standard medical care. In these situations, glutamine should only be prescribed and monitored by a doctor. Glutamine use in healthy people does not yet have solid research to support its effectiveness, so talk to your doctor before starting any glutamine supplements. While glutamine may have no side effects in most people, glutamine may worsen liver disease or cirrhosis, and may worsen certain psychiatric or seizure disorders. If you are sensitive to monosodium glutamate or MSG, glutamine supplements can make this worse. Glutamine may also interact with certain medications and dietary supplements, and so only take glutamine supplements under the supervision of a healthcare practitioner.

Reviewed by: Kay Peck, MPH, RD