Glutamine: Critical for Gut, Immune System, and Muscles during Stress and Aging

By Dr. Linda J. Dobberstein, DC, Board Certified in Clinical Nutrition

November 23, 2020

Glutamine: Critical for Gut, Immune System, and Muscles during Stress and Aging
Glutamine is the most abundant amino acid found in the human body. Glutamine provides fuel for your digestive tract, immune system, muscles, and several other tissues. During times of increased physical stress and demands, the need for glutamine rises considerably, often dramatically. Physical vitality and recovery depend upon adequate glutamine.

Glutamine 101

Your skeletal muscles make glutamine, as do lungs, liver, brain, and adipose tissue in smaller amounts. In a healthy 150-pound adult, there may be as much as 70-80 grams of glutamine found in tissues.

Other tissues use glutamine to maintain structure and function. These include the small intestine, kidneys, some white blood cells, and the inner lining of blood vessels. In a healthy individual, there is an ongoing balanced ebb and flow of glutamine production and use in the body. Because glutamine can be made to keep up with basic demands, glutamine is considered a conditionally essential amino acid.

However, during times of physical stress, illness, and trauma, glutamine becomes an essential amino acid. The aging process also adds to the requirements for glutamine. The intestinal mucosal lining, leukocytes/immune system, and kidneys rapidly use glutamine for repair and metabolic needs, so it is pulled from muscles and other tissues to meet demands. The increased demands require additional support.

Glutamine production may also be reduced during high physical stress, which further depletes your reserves. Loss of glutamine stores may be experienced as muscle wasting, weakness, fatigue, gastrointestinal concerns, and slow recovery following an illness or after an exhaustive day of physical labor or intense exercise. Loss of muscle strength with aging may also occur. Adequate glutamine provides the necessary fuel for recovery and strength.

There are additional factors that interfere with glutamine production such as a low carbohydrate diet, some thyroid disorders, steroid use, and insulin levels. If you follow a low carb/keto-diet or do intermittent fasting, you may notice diminished muscle strength and physical stamina. This may reflect glutamine needs are not being met.

Gut Health and Glutamine

One of the most well-known benefits of glutamine is that it provides “food” for cells (enterocytes) that form the inner lining of your small and large intestine. Glutamine is the primary amino acid needed to maintain intestinal barrier integrity. A healthy mucosal barrier keeps unwanted particles in the digestive tract from entering the blood stream and stressing tissues.

Glutamine provides fuel for healthy gut flora, which supports gut motility and bowel movements. It helps stop germs from adhering to the inner lining of the gut wall. Glutamine also helps decrease the ratio between Firmicutes-to-Bacteroidetes. High levels and ratio of Firmicutes is undesirable as it is linked with obesity, gut dysbiosis, and other chronic disorders.

On the inner lining of the intestinal tract are villi, which are small, finger-like projections that increase the surface area of the intestinal tract. These villi are essential for nutrient absorption. Healthy villi look like a thick, deep plush carpet, whereas broken down villi makes the intestinal lining look like a thin, worn-down Berber carpet.

Numerous factors wear down intestinal villi and damage the intestinal barrier. Common factors include modern food processing, food additives, several medications like aspirin, ibuprofen, steroids, pesticides/herbicides, chemotherapy, trauma, infection, and gluten-containing foods. Gluten is found in foods made with wheat, rye, barley, and sometimes oats, and includes white flour, wheat flour, whole-grain, and sour-dough products. Glutamine provides fuel and substrates that protect intestinal barrier integrity and help build villi within the small intestine.

Glutamine and Competent Immune Function

Glutamine also provides important fuel for the immune system. Lymphocytes, a class of white blood cells such as T cells, B cells, and natural killer cells, need glutamine for normal cell production and proliferation. This is essential for fighting germs. In times of stress, lymphocytes, and other immune cells like neutrophils, macrophages, cytokines, and other types of cells rapidly use glutamine just as much, or more, than glucose to mount an immune response against germs and repair.

In addition, glutamine is one of three critical amino acids that form glutathione, your master antioxidant system. Glutamine is required for proficient immune function.

Glutamine, Muscle Strength, and Recovery

Glutamine enhances muscle strength, stamina, and endurance and has been shown to facilitate a faster recovery time in times of illness and physical distress. Athletes may experience enhanced glycogen stores and improved detoxification of ammonia with glutamine supplementation.

Healthy Aging for the Elderly

Research shows that glutamine supplementation can support healthy aging and muscle strength in the elderly when combined with physical strength training. Elderly adults who supplemented with glutamine experienced improved glutathione levels and less oxidative stress reflecting healthy aging.

Glutamine plays a profound role in gastrointestinal health, immune actions, and more. It is the most abundant amino acid in the body, but during times of physical distress and high repair needs, tissue needs substantially increase. Make sure you give your gut, immune system, and muscles the amino acid fuel that it needs to repair and revitalize.

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