Your body is an amazing collection of parts, from big things like your bones to tiny elements like amino acids. Amino acids are important—they make up proteins that build muscle and bone—and you can help support them in different ways. One is by taking the supplement L-glutamine, which been linked to having a more efficient immune system, good intestinal health, better exercise performance, and more.
Essentially, L-glutamine is the supplement form of glutamine, an amino acid. It typically comes in the form of powders, capsules, tablets, or liquids. And although L-glutamine isn't as well known as other popular supplements like vitamin C and calcium, that doesn’t mean it’s not worth learning about.
The supplement world can be a little confusing and it can be tough to figure out which ones are worth your time—and which you can take a hard pass on. So, what’s the deal with L-glutamine and should you consider it? Below, dietitians and a functional medicine physician break down what L-glutamine is, the potential benefits, and side effects to watch out for.
Meet the experts: Keri Gans, RD, is the author of The Small Change Diet. Dana Ellis Hunnes, PhD, MPH, RD, is a clinical inpatient dietitian at RR-UCLA Medical Center, an adjunct assistant professor at the UCLA Fielding School of Public Health, and author of Recipe for Survival: What You Can Do To Live a Healthier and More Environmentally Friendly Life. Stacie Stephenson, DC, CNS is a doctor of chiropractic medicine, functional medicine expert, and author of Vibrant: A Groundbreaking Program to Get Energized, Own Your Health, and Glow.
What is L-glutamine?
First, you should know L-glutamine is the supplement form of glutamine, the most abundant amino acid in your body. “Amino acids are what people often call the building blocks of the body because they are components of proteins that the body uses to build muscle, bone, and tissue,” explains Stacie Stephenson, a functional medicine expert and the author of Vibrant: A Groundbreaking Program to Get Energized, Own Your Health, and Glow. Amino acids also help with a range of biochemical processes in your body, like the functioning of your immune system, brain, and digestion.
Most glutamine is stored in muscles, followed by the lungs where much of this amino acid is made, according to Mount Sinai. Glutamine is considered a non-essential amino acid because “our body naturally makes it on its own,” says Keri Gans, RD, the author of The Small Change Diet.
Still, you can get glutamine from some foods, including chicken, fish, cabbage, spinach, dairy, tofu, lentils, beans, nuts, and mushrooms, says Dana Ellis Hunnes, PhD, MPH, RD, an adjunct assistant professor at the UCLA Fielding School of Public Health and the author of Recipe for Survival: What You Can Do To Live a Healthier and More Environmentally Friendly Life.
You can take L-glutamine if you want an extra boost of this nutrient, especially if you suffer from a condition that lowers its levels like injuries, infections, and chronic stress. “In medical-care settings, it is also used in patients who have burns—it helps burns heal more quickly,” Hunnes says. “We also use it in critically ill patients in the ICU, as it has been shown to reduce complications.”
What are the benefits of L-glutamine?
L-glutamine is used for a variety of different reasons. Here are some of the major benefits.
It can help with wound healing.
This is a biggie and it’s one of the supplement’s “main benefits,” Gans says. The way this works is a little complicated, but basically when you have an injury, burn, or surgical procedure, your body releases the stress hormone cortisol. Higher levels of cortisol work against your body’s supply of glutamine.
Research has shown that adding glutamine to a feeding tube in trauma and critically ill people lowers their risk of death. Glutamine also been found to help people with severe burns recover faster, per a 2019 review in the journal Nutrition in Clinical Practice.
It may promote gut health.
L-glutamine may help support the gut microbiome and modulate inflammation, according to a 2021 review in Food Science and Human Wellness. “It appears to help strengthen the gut wall, potentially helping with leaky gut and improving the symptoms of irritable bowel syndrome,” Stephenson says.
It may support immune health.
Glutamine is considered the fuel of the immune system. While glucose is the main source of energy for your body, immune system cells like lymphocytes and neutrophils use glutamine at a similar or higher rate as glucose.
“Because of its potent contribution to immune function, L-glutamine is a good supplement for anyone who is immunocompromised,” Stephenson says. “It is often recommended as part of a clinical nutrition supplementation program for immune-suppressed people.”
It seems to help fight severe weight loss.
There have been several studies of people with HIV or AIDS who have had severe weight loss due to their illness and took L-glutamine (along with other nutrients like vitamins C and E). Research has found that the supplement may help with weight gain and help the gut absorb nutrients better.
It may help with muscle recovery.
L-glutamine has also been studied as a supplement for athletes who have fatigue. “It has shown some promise with recovery and performance,” says Stephenson.
However, a 2019 review in the journal Clinical Nutrition concluded that glutamine supplementation has no impact on the immune health of athletes, sports performance, or body composition. More research is needed to find out what glutamine can do in this area.
It can combat the effects of stress.
“If you are under a lot of stress, including physical stress like an injury, illness, or extreme physical work and mental stress, then your body may not be making enough L-glutamine,” Stephenson says. “This could in turn impact your immunity, so it can be a valuable supplement for stress—it could help you feel better able to cope with stress, and also help you to avoid getting sick from the immune-suppressing effects of extreme stress.”
A 2020 Nutrients study found that taking a glutamine supplement may even help protect against chronic stress-induced mild cognitive impairment. However, the study was only conducted in mice, so further research is required to see whether it would do the same for humans.
Does L-glutamine cause any side effects?
In general, L-glutamine is considered a “very safe” supplement, Hunnes says. However, she adds, there is a chance of having the following side effects:
- Bloating
- Nausea
- Dizziness
- Reflux
- Stomach pain
Keep in mind, per Hunnes, that people with liver disease shouldn’t use L-glutamine because it can cause an altered mental status in these patients. “Also, it's not recommended in people who have bipolar disorder, people who are sensitive to MSG (monosodium glutamate), or who have seizure disorders—it may increase the likelihood of seizure,” she says.
The jury is still out on whether L-glutamine is safe for cancer patients. While it may increase the effectiveness and reduce the side effects of chemotherapy treatments such as inflammation in the digestive tract and diarrhea in people with colon cancer, research has also shown that glutamine may stimulate growth of tumors. So, cancer patients and those who are receiving chemotherapy should never add supplements without first consulting their doctor.
How much L-glutamine should you take?
The maximum suggested dose is 40 grams a day, according to Hunnes. That dose is “usually for people who have burns, trauma, or surgical recovery needs,” she adds.
You can find glutamine in the following foods.
- Beef
- Pork
- Poultry
- Fish
- Cabbage
- Raw parsley
- Raw spinach
- Dairy like milk, yogurt, ricotta cheese, and cottage cheese
- Tofu
- Lentils
- Nuts
- Mushrooms
How do you choose an L-glutamine supplement?
Experts say L-glutamine really isn’t thought to be helpful for healthy people. “It's not dangerous per se, but it hasn't shown any particular benefit over a healthy diet,” Hunnes says.
Still, if you think you could use it, Stephenson recommends looking for a supplement that lists “L-glutamine” instead of just “glutamine” to make sure you’re getting the right form. Remember: Supplements are not regulated by the U.S. Food and Drug Administration. “I always recommend going with a company you trust who uses third-party verification for quality control and purity,” she says.
L-glutamine supplements come in powders, capsules, tablets, or liquids. Be careful not to add L-glutamine powders to hot drinks because the heat destroys the amino acid. And as always, check with your health care provider before starting a supplement to make sure it's safe and won't interact with any of your existing meds or supps.
Bottom line: There are certain situations where it might be helpful to try an L-glutamine supplement for health benefits. If you're considering L-glutamine, talk to your doctor for personalized recommendations that will help steer you in the right direction.
Korin Miller
Korin Miller is a freelance writer specializing in general wellness, sexual health and relationships, and lifestyle trends, with work appearing in Men’s Health, Women’s Health, Self, Glamour, and more. She has a master’s degree from American University, lives by the beach, and hopes to own a teacup pig and taco truck one day.
