Joint/Skin

N-Acetyl D-Glucosamine

Also known as: NAG, N-Acetylglucosamine, GlcNAc

Evidence

N-Acetyl D-Glucosamine (NAG) is an amino sugar derivative that supports joint cartilage structure and skin barrier function. Evidence for joint health is mixed and moderate, with stronger evidence for gut barrier support.

Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.

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Primary uses

Joint health and cartilage support
Skin barrier function
Gut barrier integrity
Inflammatory response modulation

How it works

Provides substrate for glycosaminoglycan synthesis in cartilage matrix
Supports mucin production in intestinal lining
May modulate immune tolerance through dendritic cell signaling

Dosage

Typical range: 500-3000 mg daily
Timing: Can be taken with or without meals; consistent daily dosing recommended
With food: No specific requirement, though may be better tolerated with food
Duration: Most studies examining joint benefits used 8-16 week protocols; effects may require consistent use
Special populations: Generally safe in pregnancy and lactation; limited pediatric data

Forms

Powder· 70/100
Capsule· 70/100

Safety

Common side effects

Mild gastrointestinal upset
Nausea
Heartburn (rare)

Contraindications

Shellfish allergy (some sources derived from shellfish)
Severe liver impairment (theoretical concern)

Evidence notes

NAG has shown promise in small studies for joint health, gut barrier support, and inflammatory markers, but larger, well-designed RCTs are limited. Evidence is preliminary and inconsistent, particularly for isolated joint outcomes. Better evidence exists for combinations with glucosamine/chondroitin than NAG alone.

Grade C: Mostly observational or small trials; mechanism is plausible but unproven at scale.

Related in Joint/Skin

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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.