Glutamine

What does the research say?

Research on glutamine's effectiveness for building muscle mass is mixed. Some studies suggest that glutamine supplementation can increase muscle fiber size and upregulate protein synthesis pathways, potentially contributing to muscle hypertrophy [16] . Other research indicates that while glutamine may reduce markers of muscle damage and improve recovery, it doesn't necessarily enhance muscle building or athletic performance significantly [4] [8] [9] . It's important to note that many studies focus on glutamine's benefits in catabolic states or during periods of intense training, rather than specifically on muscle growth in healthy individuals [1] [4] [8] .

Alterations in amino acid transport

As glutamine shares transporters with other amino acids, increased intake may disrupt the distribution of amino acids among tissues and affect their absorption in the gut and kidneys [6] .

Alterations in glutamine metabolism

Supplementation may reduce the body's natural production of glutamine and increase the production of glutamate and ammonia [6] .

Alterations in ammonia transport

Glutamine supplementation may interfere with the body's ability to detoxify ammonia and affect its role in transporting ammonia between tissues [6] .

Abnormalities in aminoacidemia

Changes in plasma amino acid levels have been observed, including increased levels of glutamine, glutamate, citrulline, ornithine, arginine, and histidine, and decreased levels of valine, leucine, isoleucine, glycine, threonine, serine, and proline [6] .

Alterations in immune system

Due to its immunomodulating properties, long-term glutamine consumption may have effects on the immune system that need further investigation [6] .

Potential effect on tumor growth

There is a need to investigate whether long-term glutamine intake affects the risk of cancer [6] .

Effect of the withdrawal of glutamine supplementation

The body may adapt to high glutamine intake, so stopping supplementation could potentially lead to health issues related to glutamine deficiency [6] .

[1] Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation.

This review discusses glutamine's role in metabolism, immune function, and clinical applications. It highlights glutamine's importance for immune cells and its potential benefits in catabolic conditions, but notes a lack of evidence for muscle mass increase with supplementation alone.

[2] Glutaminolysis: A Hallmark of Cancer Metabolism.

This article reviews the role of glutamine metabolism in cancer cells, highlighting its importance in various cellular functions such as synthesis of metabolites, generation of antioxidants, and activation of cell signaling. It also discusses the potential of targeting glutamine metabolism as a therapeutic strategy for cancer.

[3] Side effects of amino acid supplements.

This review discusses the side effects of various amino acid supplements, including HMB. It mentions that HMB is generally well-tolerated but notes potential alterations in glutamine levels and ATP metabolism in some cases.

[4] Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition.

This review examines glutamine's role as an anti-fatigue agent in sports. It suggests that glutamine may improve fatigue markers and reduce muscle damage, but has limited effects on physical performance and muscle building.

[5] Glutamine as an immunonutrient.

This review focuses on glutamine's role in supporting immune function. It discusses how glutamine fuels immune cells, maintains gut barrier function, and acts as a precursor for antioxidants. The paper highlights the benefits of glutamine supplementation in critically ill patients.

[6] Side effects of long-term glutamine supplementation.

This review discusses the potential side effects of long-term, high-dose glutamine supplementation, including alterations in amino acid transport, glutamine metabolism, ammonia transport, aminoacidemia, immune function, and potential effects on tumor growth and withdrawal symptoms.

[7] II. Glutamine and glutamate.

This paper reviews the roles of glutamine and glutamate in various physiological processes, including their importance in acid-base homeostasis, nitrogen balance, and neurotransmission. It also discusses their presence in foods and their roles in health and disease.

[8] Dosing and efficacy of glutamine supplementation in human exercise and sport training.

This paper reviews the effects of glutamine supplementation in athletes, particularly in relation to immune function and exercise performance. It concludes that while glutamine supplementation can maintain plasma glutamine levels during exercise, it does not prevent post-exercise immune changes, and its suggested benefits have received little support from well-controlled studies.

[9] The effect of glutamine supplementation on athletic performance, body composition, and immune function: A systematic review and a meta-analysis of clinical trials.

This meta-analysis examines the effects of glutamine supplementation on athletic performance, body composition, and immune function. The study aims to provide a conclusive result on the overall impact of glutamine supplementation in athletes.

[10] Psat1-generated α-ketoglutarate and glutamine promote muscle stem cell activation and regeneration.

This paper discusses the role of glutamine and α-ketoglutarate in muscle stem cell activation and regeneration. It highlights that supplementation with these metabolites can improve muscle regeneration in certain conditions, suggesting their potential role in muscle repair and growth.

[11] Lung glutamine metabolism.

This article reviews the role of the lungs in glutamine metabolism, suggesting that the lungs play a key role in maintaining glutamine homeostasis in both normal and catabolic states.

[12] The evidence for glutamine use in the critically-ill.

This paper discusses the evidence for a conditional glutamine deficiency in trauma and sepsis, and the potential benefits of glutamine supplementation in improving clinical outcomes, including immune function and survival from infection.

[13] Glutamine.

This review discusses glutamine's role as a fuel for rapidly dividing cells, its importance in nitrogen transport, and the potential for glutamine deficiency during metabolic stress. It also reviews evidence for the benefits of glutamine in enhancing gut barrier function.

[14] Glutamine and cancer.

This overview discusses the importance of glutamine for tumor growth, alterations in interorgan glutamine metabolism in tumor-bearing hosts, and the potential benefits of glutamine nutrition in cancer patients.

[15] Nutrition and metabolism of glutamate and glutamine in fish.

This review discusses the roles of glutamate and glutamine in fish, highlighting their importance for growth, intestinal health, immune responses, and muscle development. It suggests that dietary supplementation with these amino acids can improve various aspects of fish health and productivity.

[16] Changes in Skeletal Muscle Protein Metabolism Signaling Induced by Glutamine Supplementation and Exercise.

This study investigated the effects of glutamine supplementation and resistance exercise on muscle protein metabolism. It found that glutamine supplementation increased muscle fiber size and upregulated protein synthesis signaling pathways, suggesting a potential role in muscle hypertrophy.

[17] Glutamine nutrition: theoretical considerations and therapeutic impact.

This paper discusses the potential therapeutic impact of glutamine-supplemented diets in critically ill surgical patients, suggesting that tailored diets may play an important role in specific clinical settings.