In cancer, glutamine is not a treatment for the disease but supportive care to ease mouth sores, diarrhea, skin injury, and nerve pain from chemotherapy and radiation, and to aid recovery after surgery. Benefits are real but modest and inconsistent. It is well tolerated, though harmful in significant liver disease, and may theoretically feed some tumors. (Full Review)

Protocol

Standard Dose

~30 g/day

Roughly 10 g three times daily, or about 0.5 g/kg per day; split across the day

Timing

Before & through treatment

Begun a few days before chemotherapy or radiation and continued through treatment

Route by Target

Swish or dissolve

Swish-and-swallow suspension for the mouth lining; powder dissolved in water for gut and skin

Time to effect

Mucosal & Gut Symptoms

Over days

Benefit unfolds over days of consistent use across a treatment cycle, not from a single dose

Benefits

Medium: Reduced oral mucositis severity; less chemotherapy- and radiation-induced diarrhea; less moderate-to-severe radiodermatitis; better postoperative immune markers and fewer surgical complications

Low: Reduced chemotherapy-induced peripheral neuropathy; reduced paclitaxel-associated muscle and joint pain; preserved lean mass and nitrogen balance

Speculative: Direct antitumor or chemo-sensitizing effect

Contraindications

Cirrhosis

Hepatic encephalopathy

Child-Pugh Class C liver disease

Inherited urea-cycle disorders

Severe kidney impairment

Key Interactions

Chemotherapy agents (paclitaxel, oxaliplatin, 5-fluorouracil, irinotecan, anthracyclines)

Lactulose and other ammonia-lowering therapy

Anticonvulsant medications

Growth hormone

High-dose N-acetylcysteine and other antioxidant supplements

Active glutamine-avid digestive-tract tumors

Monosodium glutamate sensitivity

Risk & Side Effects

Medium: Gastrointestinal discomfort at higher doses

Low: Elevated blood ammonia in liver impairment; theoretical reduction of chemotherapy efficacy

Speculative: Promotion of tumor growth

Monitoring

Marker	Target	Why
Blood ammonia	Within the low-normal laboratory range	Detects glutamine-driven ammonia rise before symptoms
ALT / AST	Roughly 10–30 U/L	Screens for liver impairment that raises ammonia risk
BUN / creatinine	Within normal range for age	Assesses kidney handling of the nitrogen load
Complete blood count	Within normal range	Tracks treatment-related marrow and immune effects
Serum albumin / prealbumin	Albumin above about 4.0 g/dL	Reflects nutritional status and repair capacity

Cadence: Baseline, then at each treatment cycle or radiation week; every 3–6 months if use continues

Qualitative Assessment

Severity of mouth soreness and ability to eat and drink
Frequency and looseness of stools
Skin comfort in the radiation field
Numbness, tingling, or pain in the hands and feet
Energy levels and overall treatment tolerance

Glutamine to Treat Cancer

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment