L-Glutamine

Semi-essential amino acid crucial for gut health, immune function, and muscle recovery

Scientific nameL-Glutamine FormulaC5H10N2O3 Molecular weight146.14 g/mol CAS56-85-9

85 absorption score

8 safety / 10

30 USD per month

5 documented interactions

Check it against something

Evidence level B

L-Glutamine with:

78 out of 100

Works better together Compatible. Timing differs, so follow each supplement's own window.

Check it against your whole stack →

What it does

mechanism and evidence for each claim

Enhanced gut barrier function

Supports intestinal lining integrity and digestive health

Primary fuel source for enterocytes and gut mucosal cells Evidence A-grade 2-6 weeks

Improved muscle recovery and growth

Supports muscle protein synthesis and reduces exercise-induced breakdown

Provides nitrogen for protein synthesis and prevents muscle catabolism Evidence A-grade 1-4 weeks

Enhanced immune system function

Supports immune cell proliferation and function

Primary fuel for lymphocytes and other immune cells Evidence A-grade 2-4 weeks

Reduced intestinal permeability

Helps heal leaky gut syndrome and intestinal inflammation

Essential for tight junction proteins and mucosal repair Evidence B-grade 4-12 weeks

Improved exercise performance

May enhance endurance and reduce fatigue

Prevents ammonia buildup and supports energy metabolism Evidence B-grade 2-6 weeks

Others take these for the same thing

Same goal, different mechanism — check any of them against this one

Creatine Monohydrate Strength & power enhancement 3-5g A 95% Probiotics for Autoimmune Disease Support Gut health & immune modulation 10-100 billion CFU daily B 60% Calcium Bone health & muscle function 1,000-1,200 mg A 30% Magnesium Glycinate Superior absorption sleep & muscle support 200-600 mg A 90% Magnesium Citrate Balanced absorption & digestive support 300-600 mg A 35% Chloride Electrolyte & digestive support 2300mg A 95%

Every pair we checked

12 combinations scored by the engine

L-Glutamine + Caffeine No documented interaction either way No known interaction 70

L-Glutamine + Creatine Monohydrate No documented interaction either way No known interaction 70

L-Glutamine + Vitamin D3 No documented interaction either way No known interaction 70

L-Glutamine + Calcium Carbonate No documented interaction either way No known interaction 70

L-Glutamine + Whey Protein No documented interaction either way No known interaction 70

L-Glutamine + Lactase No documented interaction either way No known interaction 70

L-Glutamine + Bovine Collagen No documented interaction either way No known interaction 70

L-Glutamine + DHA No documented interaction either way No known interaction 70

L-Glutamine + Turmeric No documented interaction either way No known interaction 70

L-Glutamine + Zinc Gluconate Both support gut barrier function and immune health Works better together 78

L-Glutamine + Lactobacillus acidophilus Support gut health and microbiome balance Works better together 78

L-Glutamine + L-Leucine Enhanced muscle protein synthesis and recovery Works better together 82

Dosage

Post workout or empty stomach

Daily5-15g

Gut health10-15g daily (divided)

Muscle recovery10-15g post-workout

Immune support5-10g daily

Therapeutic20-40g daily (medical supervision)

Before you take it

VeganYes

When to expect it

First Effects1-2 weeks for gut health and recovery benefits

Peak Benefits4-8 weeks for sustained digestive and immune benefits

Deficiency DevelopmentDays to weeks during stress, illness, or intense training

Toxicity OnsetRare, mainly concerns for bipolar individuals

How to measure it

$80-200

MarkerPlasma glutamine levels or intestinal permeability tests

Optimal500-750 μmol/L

Deficient below<400 μmol/L

FrequencyOnly if monitoring gut health or critical illness recovery

What people actually reported to the FDA

CAERS, 45 reports naming it as the suspect

Most reported effects

Dizziness 7

Abdominal pain 6

Feeling abnormal 5

Insomnia 5

Anxiety 5

Named as the suspect 45 reports of 70 that mention it at all

Serious outcome 82% hospitalisation, emergency room or worse

Other Serious or Important Medical Event27

Hospitalization17

Visited Emergency Room15

Reports are voluntary and unverified — they record what someone experienced while taking something, not what the compound caused. Counts skew towards products people take a lot of, and a serious outcome is more likely to be reported than a mild one, so these are not rates. How we filter them →

What actually reaches you

The label counts the carrier, your body does not

Absorption Very high 85 of 100 · best absorbed form of this compound

Delivered daily 8500 mg

Cost per 100 mg delivered $0.01 comparative — uses the absorption score, not a measured percentage

Works better with

3 documented

Zinc

Both support gut barrier function and immune health

Complementary roles in intestinal healing and immunity · level B

L Leucine

Enhanced muscle protein synthesis and recovery

Complementary effects on muscle anabolism · level A

Probiotics

Support gut health and microbiome balance

Glutamine feeds beneficial bacteria and gut cells · level B

What not to take with L-Glutamine

2 documented

Alcohol

Alcohol depletes glutamine and damages gut lining

Interferes with glutamine metabolism and gut health · major significance

Nsaids

NSAIDs can damage gut lining that glutamine supports

Opposing effects on intestinal integrity · moderate significance

Medication interactions

Discuss these with a pharmacist before combining

anticonvulsants Moderate

Glutamine may reduce seizure threshold

What to do: Use caution in epileptic individuals

lactulose Minor

May enhance ammonia-lowering effects

What to do: May be beneficial for hepatic encephalopathy

Available forms

bioavailability compared

L-Glutamine (Free Form) 85

L-Glutamine (Free Form): Gut healing, Muscle recovery, Immune support, Well-researched

Food sources

before you supplement

Meat and poultry 1.2-1.8g per 100g · 85

Fish and seafood 1.0-1.5g per 100g · 85

Dairy products 0.6-1.2g per 100g · 80

Eggs 0.6g per 100g · 90

Too little

deficiency signs

Poor gut barrier function and leaky gut
Slow muscle recovery and increased breakdown
Impaired immune function and frequent infections
Poor wound healing
Digestive issues and intestinal inflammation
Muscle wasting during stress or illness
Increased susceptibility to infections

Too much

toxicity signs

Generally well-tolerated:
Potential mania in bipolar individuals
Mild digestive upset with very large doses
MSG-like symptoms in sensitive individuals
Excellent safety profile for most people

Who benefits most

gut-health-leaky-gut

Essential for intestinal barrier function and gut healing

10-15g daily (divided doses)

athletes-muscle-recovery

Supports muscle recovery and reduces exercise-induced breakdown

10-15g post-workout

immune-support

Primary fuel for immune cells and immune function

5-10g daily

inflammatory-bowel-disease

May help reduce intestinal inflammation and promote healing

10-20g daily (medical supervision)

critical-illness-recovery

Becomes essential during severe stress and illness

Medical supervision required

Where to buy it

compare forms first

Look for L-Glutamine at 5-15g per serving. The form that matters here is L-Glutamine (Free Form).

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What else affects it

Beyond other supplements

Alcohol

Alcohol depletes glutamine and damages gut lining

Interferes with glutamine metabolism and gut health

How it works

Primary fuel source for enterocytes and gut mucosal cells
Essential for lymphocyte proliferation and immune function
Provides nitrogen for protein synthesis and tissue repair
Important for tight junction protein maintenance
Supports glutathione synthesis as glutamate precursor
Essential for gluconeogenesis and glucose production

Key findings

what the evidence supports

Essential for gut barrier function and intestinal health
Effective for muscle recovery and reducing exercise-induced damage
Important for immune system function and critical illness recovery
Generally safe but caution needed in bipolar disorder

Sources: NIH Examine.com · data reviewed 2026-08-02

Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →

Common questions

What are the benefits of L-Glutamine?

Documented effects: Enhanced gut barrier function; Improved muscle recovery and growth; Enhanced immune system function; Reduced intestinal permeability. Supports intestinal lining integrity and digestive health

How much L-Glutamine should you take per day?

The common daily range is 5-15g. By goal — gut health: 10-15g daily (divided); muscle recovery: 10-15g post-workout; immune support: 5-10g daily; therapeutic: 20-40g daily (medical supervision).

When is the best time to take L-Glutamine?

Post workout or empty stomach. First effects are typically reported within 1-2 weeks for gut health and recovery benefits.

What are the side effects of L-Glutamine?

At excessive doses: Generally well-tolerated:, Potential mania in bipolar individuals, Mild digestive upset with very large doses, MSG-like symptoms in sensitive individuals, Excellent safety profile for most people. Safety rating at normal doses is 8 out of 10.

What should you not take with L-Glutamine?

Separate it from Alcohol, Nsaids by two to four hours. Alcohol depletes glutamine and damages gut lining

Does L-Glutamine interact with medications?

Documented interactions with anticonvulsants, lactulose. Discuss these with a pharmacist before combining.

How do you know if you need L-Glutamine?

The marker is Plasma glutamine levels or intestinal permeability tests, optimal range 500-750 μmol/L. Common deficiency signs: Poor gut barrier function and leaky gut, Slow muscle recovery and increased breakdown, Impaired immune function and frequent infections, Poor wound healing.

Taken for

74 Digestion

Lactase · Lactobacillus acidophilus · Protease

43 Performance

Caffeine · Creatine Monohydrate · Whey Protein