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Supplement · amino_acid

Glutamine

Quick read: Glutamine is a conditionally essential alpha-amino acid and the most abundant free amino acid in human plasma and muscle tissue.

Quick facts · L-Glutamine

Dose
5 g
Per day
15 g
Timing
Between meals · 3 times a day
Course
90 days + break 30 days
Strongest effect
Workout Efficiency EnhancementHighClinical
Scientific background
Glutamine is a conditionally essential alpha-amino acid and the most abundant free amino acid in human plasma and muscle tissue. While endogenously synthesized, its requirements can exceed production during periods of physiological stress, such as intense exercise, critical illness, or trauma. Biologically, glutamine serves as a crucial nitrogen donor and carbon source, playing a pivotal role in diverse metabolic processes. Its primary mechanisms of action include serving as a critical precursor for nucleotide synthesis (essential for DNA and RNA production in rapidly dividing cells like immune cells and enterocytes), participating in ammonia detoxification, and supporting the synthesis of glutathione, a major endogenous antioxidant. Furthermore, glutamine is vital for maintaining gut barrier integrity by fueling enterocytes and regulating immune cell function. In a clinical context, supplementation is frequently considered to support immune function, preserve gut integrity, and aid muscle recovery during states of increased metabolic demand or catabolism. Research continues to explore its benefits in diverse conditions, from supporting critically ill patients to enhancing athletic performance and mitigating exercise-induced immune suppression. Its multifaceted role underscores its significance in human health.

Form & dosage

Single dose
5 g
Daily
15 g
Course
90 days
Break
30 days
Timing
Between meals · 3 times a day
How we rate evidence

Probability — how likely the effect is to show up

  • Very high
  • High
  • Medium
  • Low

Evidence — where the data comes from

  • Scientific Meta-analyses and randomized trials
  • Clinical Clinical trials and practice
  • Animal research Animal studies
  • People reports User reports and anecdotes
  • Theoretical Mechanistic reasoning, not yet tested

Effects

High probability(5)

  • Digestion Improvementhealththeoretical

    Glutamine serves as the primary fuel for gut cells, crucial for maintaining intestinal barrier integrity and preventing 'leaky gut', which directly supports overall digestive health and nutrient absorption.

  • Fatigue Reductionpsychetheoretical

    By facilitating cellular energy production and accelerating recovery from physical exertion, glutamine helps combat both general and exercise-induced fatigue, leading to sustained vitality and alertness.

  • Workout Efficiency Enhancementbodyclinical

    By enhancing muscle recovery, reducing catabolism, and supporting immune function, glutamine enables more consistent and higher-quality training sessions, leading to improved adaptations and greater overall gains from workouts.

  • Immune System Supporthealththeoretical

    As a vital fuel for rapidly dividing immune cells like lymphocytes, glutamine ensures robust immune function and enhances the body's ability to defend against pathogens, especially during periods of stress or intense training.

  • Muscle Recovery Accelerationbodytheoretical

    Glutamine accelerates muscle repair by replenishing glycogen stores, reducing protein breakdown, and aiding in protein synthesis post-exercise, which effectively diminishes muscle soreness and speeds up readiness for the next workout.

Medium probability(8)

  • Antioxidant Protection Enhancementhealththeoretical

    As a vital precursor to glutathione, the body's master antioxidant, glutamine supports the natural synthesis of this powerful compound, thereby boosting overall antioxidant defenses and protecting cells from oxidative damage.

  • Wound Healing Accelerationbodytheoretical

    Glutamine is indispensable for the rapid proliferation of cells involved in tissue repair, making it crucial for accelerating the healing process of various wounds, from surgical incisions to intestinal lining damage.

  • Inflammation Reductionhealththeoretical

    Glutamine helps modulate the immune response within the gut, reducing the production of pro-inflammatory cytokines and supporting a healthy intestinal lining to alleviate localized and systemic inflammation.

  • Physical Endurance Increasebodytheoretical

    By supporting the body's ability to buffer ammonia and maintain hydration, glutamine, particularly its dipeptide forms, helps sustain energy levels during prolonged physical exertion, allowing for enhanced endurance.

  • Gut-Brain Axis Supporthealththeoretical

    By fortifying the gut barrier and soothing intestinal inflammation, glutamine indirectly fosters a healthier gut-brain connection, potentially contributing to improved mood and cognitive clarity through reduced systemic stressors.

  • Muscle Mass Preservationbodytheoretical

    Glutamine acts as a potent anti-catabolic agent, helping to prevent muscle protein breakdown, especially during calorie deficits or periods of intense physiological stress, thereby supporting the maintenance of lean muscle mass.

  • Antibiotic Recoveryhealthclinical

    After antibiotic use, glutamine helps to repair the integrity of the intestinal barrier and promotes a healthier environment for beneficial gut bacteria, aiding in the restoration of balanced digestion and overall well-being.

  • Hydration Supportbodytheoretical

    While all forms contribute, the dipeptide form of glutamine, L-Alanyl-L-Glutamine, uniquely enhances intestinal absorption of water and electrolytes, optimizing cellular hydration and electrolyte balance crucial for performance, especially in hot conditions.

Side effects

Medium probability(2)

  • Digestive Discomforthealthclinical

    Your gut might feel a bit unsettled with glutamine, manifesting as general unease, mild cramps, or a sense of fullness. This often happens because your digestive system is adjusting to the supplement, especially when starting with higher doses or taking it without food, as it can draw water into the intestines.

  • Abdominal Bloatinghealthpeople_reports

    Feeling a bit puffy or gassy after taking glutamine is a common experience. This can occur because glutamine, particularly in larger amounts, can pull water into your intestines or get fermented by gut bacteria, leading to excess gas and a sensation of abdominal distension.

Low probability(2)

  • Diarrheahealthclinical

    Some users might experience loose stools or diarrhea, particularly if they take a large dose of glutamine, as its osmotic effect can draw more water into the bowel, speeding up transit time and making stools watery.

  • Nauseahealthpeople_reports

    An upset stomach or feeling queasy can sometimes accompany glutamine intake, especially if you take a large dose on an empty stomach. This reaction is usually mild and often subsides once your body adjusts or if the supplement is taken with food.

Low probability(4)

  • Heartburn / Refluxhealthpeople_reports

    Some people might experience a burning sensation in the chest or throat, similar to heartburn. This is usually due to glutamine mildly irritating the stomach lining, especially when taken without food, or in sensitive individuals.

  • Vomitinghealthpeople_reports

    While uncommon, severe nausea caused by glutamine, particularly from very high doses or when taken on an empty stomach, can sometimes escalate to vomiting. This is often a sign that the dosage is too high for your system or that it needs to be taken with food.

  • Constipationhealthpeople_reports

    While less common than diarrhea, some individuals might find their bowel movements slow down or become more difficult. This can happen if glutamine causes an osmotic shift that reduces water in the colon, or if overall fluid intake is insufficient.

  • Headachehealthpeople_reports

    A mild headache can occasionally occur as a side effect. This is typically due to individual sensitivity or minor dehydration, which can be exacerbated if not enough water is consumed alongside the supplement.