Glutamine's strongest evidence supports medical use — easing gut and mouth damage from cancer treatment and aiding recovery after surgery or injury. For healthy adults, support for strengthening the gut lining is reasonable; benefits for muscle soreness, immune defense, and inflammation are weaker. Everyday doses are well tolerated; very high doses harmed critically ill patients. (Full Review)

Protocol

Standard Dose

5 g, 1–3× daily

Unflavored powder in cool water; ~5–15 g/day for gut-barrier support

Timing

Between meals or post-training

Away from high-protein meals for gut goals; after exercise for recovery

Dosing Pattern

Split 5 g servings

Preferred over a single large dose; keep at or below ~14 g/day

Time to effect

Gut Barrier

2–4 weeks

Noticeable changes with consistent use

Exercise Recovery

Acute

Within the days around training

Performance & Body Comp

None expected

No performance or body-composition change at any point

Benefits

High: Reduced mucositis and diarrhea from cancer treatment

Medium: Intestinal barrier integrity; reduced complications and length of stay after surgery or injury

Low: Muscle soreness and strength recovery after exercise; immune support in heavy training; improved inflammatory and cardiometabolic markers

Speculative: Reduced sugar cravings and appetite regulation; direct longevity and healthspan effects

Contraindications

Advanced liver disease (Child-Pugh B–C cirrhosis, hepatic encephalopathy)

Significant kidney impairment (eGFR below 30)

Bipolar disorder

Seizure disorder

Active gastrointestinal or liver cancer

Urea-cycle disorders

Key Interactions

Anti-seizure medications (valproate, phenytoin, carbamazepine)

Lactulose and other ammonia-lowering therapies

Chemotherapy agents (paclitaxel, cisplatin, fluorouracil)

Growth hormone therapy

Branched-chain amino acids (leucine, isoleucine, valine)

Monosodium glutamate, high-dose amino acid blends

Risk & Side Effects

High: Increased mortality with high-dose use in critically ill patients

Medium: Gastrointestinal discomfort at higher doses; ammonia accumulation in liver impairment

Low: Potential to serve as fuel for tumor growth; interference with anti-seizure control; triggering of mania in bipolar disorder

Speculative: Unknown long-term safety of chronic high-dose supplementation

Monitoring

Marker	Target	Why
Blood ammonia	15–45 µmol/L	Central safety marker; glutamine metabolism generates ammonia
ALT / AST	ALT 10–26 U/L; AST 10–26 U/L	Confirms liver capacity to clear ammonia before and during use
BUN	10–16 mg/dL	Reflects nitrogen load and kidney handling of protein metabolism
eGFR	>90 mL/min/1.73m²	Ensures adequate clearance before higher-dose use
hs-CRP	<1.0 mg/L	Tracks the inflammatory marker glutamine may modestly improve
Fasting glucose	75–90 mg/dL	Monitors the metabolic marker relevant to appetite/glycemic claims

Cadence: Baseline before starting, then re-check at 8–12 weeks and every 6–12 months; every 4 weeks for borderline liver/kidney values or higher doses

Qualitative Assessment

Digestive comfort and regularity (reduced bloating, more consistent stools)
Frequency and duration of minor infections such as colds, especially around heavy training
Perceived recovery and muscle soreness after intense exercise
General energy levels and, for some, reduced sugar cravings

Glutamine for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment