Health Benefits of L-Glutamine (Backed by Research)

Glutamine is a very important amino acid that plays several roles in the body. It contributes to the building of proteins and is a very vital component of the immune system. Also, it plays a very important role in digestive health.

Glutamine is produced naturally by your body, and it’s also present in many natural foods. However, you may not be so sure whether you need more of it from supplements for good health.

This article highlights the importance of glutamine and also discusses its safety levels and health benefits.

Overview of glutamine

Glutamine is a well-known amino acid. An amino acid is a molecule that serves as the building block of proteins.

Proteins are very vital to your body organs. They serve other roles, like helping in the transport of substances in the blood, and protecting the body from harmful bacteria and viruses (1).

Like most amino acids, glutamine exists in two forms – L-glutamine, and D-glutamine.

They have a close semblance to each other. However, their molecular arrangement is slightly different (2).

L-glutamine is found in supplements and foods. Many supplements list it as L-glutamine. Others just call it glutamine.

L-glutamine is vital for the building up of proteins. It also performs several other functions. On the other hand, D-glutamine may not have many roles to play in living organisms (3, 4).

The human body produces L-glutamine naturally. It is the most abundant amino acid in the body fluids (5, 6).

But then, there are times when your body may need more glutamine than it can produce (7).

Thus, it is considered an essential amino acid. What this means is that in some cases (like illness or injury), you must get it from your diet (8).

It is also important to note that glutamine is very vital to the health of your intestines as well as your immune system (9).

Sources of glutamine

Glutamine occurs naturally in several foods. Studies have shown that at least 3-6 grams are contained in a typical daily diet. However, this amount varies depending on your kind of diet (10).

Large amounts of glutamine are found in animal products because of their high protein content.

However, some plant foods contain more glutamine in their protein.

A particular study determined the amount of L-glutamine in various foods using advanced lab techniques (11).

Below we have the percentage content of protein made of L-glutamine in each food:

• Corn: 4g per 100g of corn (16.2%)
• White rice:3g per 100g of rice (11.1%)
• Tofu:6g per 100g of tofu (9.1%)
• Skim milk: 3g/100g (8.1%)
• Beef: 2g per 100g of beef (4.8%)
• Eggs:6g per 100g (4.4%)

It is worth noting that some plant foods, like corn and white rice, have more glutamine, their overall protein content is quite low (11, 12, 13).

So, the best way to get high amounts of glutamine is from meats and other animal foods.

However, we do not know the exact glutamine content in every food. No studies have been done on these.

However, because glutamine is an important component of proteins, most foods containing protein will contain some amount of glutamine.

Focusing on adequate protein intake in your daily diet is a very easy way to increase your daily glutamine intake.

It is important for immune function

One of the major roles of glutamine in your body is its ability to boost immune function.

It energizes immune cells, like some intestinal cells and white blood cells (14).

However, certain factors may cause a decrease in the blood levels of L-glutamine. These include surgeries, burns, or major injuries (15, 16).

If your body's glutamine requirements are greater than what it produces, then your body may deplete protein stores, like the muscle, to get more of this amino acid (17, 18).

Also, immune function may be compromised when you’re deficient in glutamine (17, 19).

This explains why high-glutamine diets, high-protein diets, or glutamine supplements are often prescribed after burns or other major injuries (17).

Research has also shown that glutamine supplements decrease the risk of infections, improves health, and also shortens hospital stays after surgery (20, 21).

It is also worth noting that L-glutamine improves the chances of survival in patients with chronic ailments (22, 23).

Other studies suggest that glutamine supplements may boost immunity in animals with viral or bacterial infections (19, 24).

However, healthy adults may not benefit much from it, as their glutamine needs may be met through the body’s natural production and diet (25).

It promotes intestinal health

The immune benefits of glutamine are associated with its role in intestinal health.

Do you know that your intestines are the largest portion of your immune system? Yes!

This is attributed to the many intestinal cells that possess immune functions, and also the many bacteria that reside in your intestines and impact on your immunity (26).

Glutamine is a major source of energy for cells of the intestine and immune system (9, 14).

It maintains the barrier that separates the inside of your intestines from the rest of your body, thus preventing a leaky gut condition (6, 27).

This prevents the movement of harmful toxins or bacteria from your intestines into the rest of your body (28).

Also, it contributes to the growth and maintenance of intestinal cells (6, 27).

Because of the role played by intestines in the immune system, glutamine may boost your immune health by enhancing the functionality of your intestinal cells (19, 26).

Effects on exercise performance and muscle gain

Because of its role as a building block of proteins, medical researchers have conducted tests to determine whether glutamine supplement improves exercise performance or muscle gain.

In a particular study, 31 people took either a placebo or glutamine for six weeks. They did weight training while taking the treatment (29).

After the study, the researchers observed improvements in muscle strength and mass in both groups. However, no significant differences were observed.

Further studies have equally shown that it doesn't have much effect on muscle performance or muscle mass (30, 31).

However, several pieces of research have reported that supplementing with glutamine may heal muscle soreness and enhance recovery after intense exercise (32).

To buttress this point, a particular study found that glutamine alone, or glutamine in combination with carbohydrates reduced blood markers of fatigue during a 2-hour race (33).

L-glutamine has also been used to boost immune function in athletes. This has yielded varying results (34, 35, 36).

Other studies did not observe any improvement in the recovery of glycogen when added to carbohydrates and some amino acids (37).

This implies that there is little or no evidence to show that these supplements are beneficial for muscle strength or gain. Evidence for other effects is limited but there is a need for further research.

Also, many athletes take in high amounts of protein in their daily diets, implying that they may be taking in adequate glutamine (38).

Conclusion

Glutamine is an amino acid that is present in two forms: L- and D-glutamine.

L-glutamine is more viable and of physiological importance. It is produced naturally in the body and is present in many natural foods. According to estimates from studies, a typical diet may have a glutamine content of 3-6g daily.

Glutamine is an energy source for intestinal and immune cells and maintains the connections in the intestines.

When your body is unable to produce enough of it, like in severe illness or injury, then you will have to supplement it.

Glutamine is also an important sports supplement. However, its effectiveness here is not backed by many studies.

Supplementing is safe, at least in the short-term, but there is a need for further research on its long-term effects.

Before supplementing with glutamine, consider whether your reason for taking it is backed by current evidence.