Does Glutamine Help When You're Sick?

December 18, 2025 •

4 min read

Over 20% of the total amino acid pool in the blood is composed of glutamine, which serves as a crucial fuel source for immune cells. During illness, trauma, or severe stress, the body's need for glutamine can exceed its natural production, raising the question of whether supplementation can help when you're sick.

Quick Summary

During periods of illness, the body's demand for glutamine increases to fuel immune cells and support gut health. While healthy individuals typically produce enough, supplementation may benefit those under severe physiological stress or recovering from major trauma. Research primarily supports its use in critical care and specific medical conditions, though potential immune benefits for less severe sickness are being explored.

Key Points

Fuel for Immune Cells: Glutamine is a primary energy source for white blood cells and lymphocytes, which are critical for fighting infections.
Conditionally Essential Nutrient: The body's need for glutamine increases significantly during severe physiological stress, such as major illness or injury.
Supports Gut Health: Glutamine maintains the health of the intestinal lining, which is a major component of the immune system.
Benefits for Severe Illness: Studies show that supplemental glutamine can improve outcomes for critically ill patients by reducing infection rates and shortening hospital stays.
Everyday Sickness Varies: For minor illnesses like a common cold, the body's natural glutamine production and dietary intake are usually sufficient for healthy adults.
Considerations and Safety: Glutamine may not be safe for those with kidney or liver disease, and long-term effects are not fully known.
Rich Food Sources: Protein-rich foods like meat, dairy, eggs, and legumes are good natural sources of glutamine.

Understanding the Role of Glutamine in Immunity

Glutamine is the most abundant amino acid in the body and plays a critical role in various metabolic processes, including immune function and gut health. Under normal circumstances, the body can produce enough glutamine to meet its needs. However, during periods of extreme physiological stress, such as major illness, injury, or intensive exercise, the body's requirement for glutamine can increase dramatically. In these catabolic states, plasma glutamine levels may drop, potentially compromising immune cell function.

Glutamine as Fuel for the Immune System

Immune cells, including lymphocytes and white blood cells, rely on glutamine as a primary fuel source to proliferate and function effectively. This is especially important when the body is fighting off an infection. The amino acid is essential for the production of cytokines, which are proteins that help regulate immune response. A decline in glutamine levels can impair the ability of these cells to defend against pathogens, increasing the risk of secondary infections.

Supporting Gut Health

Did you know that a significant portion of your immune system resides in your gut? Glutamine plays a vital role in maintaining the integrity of the intestinal lining. It acts as a primary energy source for enterocytes, the cells that line the intestines. A strong intestinal barrier is crucial for preventing harmful bacteria and toxins from entering the bloodstream, a condition sometimes referred to as 'leaky gut.' By nourishing these cells, glutamine helps support overall gut health, which in turn bolsters the immune system's front line of defense.

Glutamine in Clinical and Everyday Illness

Most of the strongest evidence for glutamine's benefits comes from studies involving critically ill or trauma patients. For these individuals, often in intensive care units, glutamine is administered intravenously or via a feeding tube. Research has shown that in these severe cases, supplementation can help reduce infection rates, shorten hospital stays, and improve recovery.

For common illnesses like a cold or the flu, the evidence is less definitive. While some sources suggest that glutamine can reduce susceptibility to infection during the cold and flu season, research for healthy adults has yielded mixed results. The body's natural production, combined with intake from a regular diet, is often sufficient to meet the needs associated with a minor illness. However, the theoretical benefit of fueling immune cells still stands, leading some wellness advocates and athletes to use it for a proactive immune boost.

Here are some of the food sources rich in glutamine that you can incorporate into your diet:

Meat and Poultry: Beef, pork, and chicken are excellent sources.
Dairy Products: Milk, yogurt, and cheese all contain glutamine.
Plant-Based Proteins: Tofu, nuts, beans, and lentils are good options for those on a vegetarian or vegan diet.
Grains and Vegetables: Wheat, oats, corn, red cabbage, and spinach also contain significant amounts.

Comparing Glutamine and Vitamin C for Illness

When considering immune support, both glutamine and Vitamin C are often discussed. While they work through different mechanisms, they can be taken together for potential synergistic benefits.


Feature	Glutamine	Vitamin C
Mechanism	Primary fuel source for immune cells; supports gut barrier integrity.	Powerful antioxidant; helps protect immune cells from oxidative stress.
Best for...	Conditions of severe stress or trauma, gut health support.	General immune bolstering, fighting off colds and flu.
Depletion Risk	High in severe illness, injury, or over-training.	Possible with insufficient dietary intake.
Synergy	May be protected by Vitamin C's antioxidant effects.	Works alongside glutamine to support overall immune function.

Potential Risks and Considerations

While glutamine is considered safe for most people, there are some important considerations. For individuals with kidney or liver disease, particularly advanced liver disease, glutamine supplementation can be dangerous and should be avoided. Anyone with a history of seizures or bipolar disorder should also use caution and consult a healthcare provider. The long-term effects of glutamine supplementation are still not fully understood, so discussing with a healthcare professional is important.

Conclusion: Making an Informed Decision

Ultimately, whether you should take glutamine when you're sick depends on the severity of the illness. For a healthy person with a common cold, simply consuming glutamine-rich foods may be enough to support the immune system. The body's natural reserves are typically sufficient for minor health challenges. However, for those recovering from major trauma, surgery, or dealing with critical illness, glutamine supplementation has a more established role, often managed in a clinical setting. As with any supplement, consulting a healthcare professional is crucial to determine if it is right for your specific health needs.

For more detailed information on glutamine's role in immune function, you can review the scientific findings published on the National Institutes of Health website at PMC6266414.

Frequently Asked Questions

There is conflicting evidence on whether glutamine boosts immunity in healthy people to prevent minor illnesses. While it is a key fuel for immune cells, a healthy adult's diet and body typically provide enough for common sicknesses.

Glutamine and Vitamin C support the immune system in different ways. Glutamine fuels immune cells and supports gut health, while Vitamin C is a powerful antioxidant. They can be taken together, but neither is definitively 'better,' as their roles are distinct.

For mild illness, your dietary intake is likely sufficient. For more serious conditions, dosing should be determined by a healthcare provider.

Potential side effects of glutamine include mild digestive issues like nausea, bloating, and stomach pain. It should be avoided by individuals with advanced liver disease, kidney disease, bipolar disorder, or a history of seizures.

Glutamine is an important energy source for the cells lining your intestines. During illness, this fuel helps maintain the integrity of the gut barrier, preventing harmful pathogens from entering the bloodstream and supporting immune function.

Foods rich in glutamine include meat, poultry, fish, dairy products like eggs, milk, and cheese, as well as plant-based sources like tofu, beans, nuts, and certain vegetables.

L-glutamine is the form of glutamine found in foods, supplements, and the human body. When most people refer to glutamine, they are referring to L-glutamine.