What is the recommended dose of glycine?

Recommended Dosage of Glycine

The recommended dosage of glycine varies by indication, but for general supplementation, 3-5 grams per day is typically recommended based on the most recent research evidence.

Clinical Applications and Dosing Guidelines

Medical Uses of Glycine

• Pharmaceutical formulations: Glycine is used as a stabilizer in certain medications and as an irrigation solution (1.5%) for urologic procedures 1
• Nutritional supplement: Functions as a precursor for several key metabolites including creatinine, glutathione, heme, purines, and porphyrins 2
• Metabolic support: May be considered a semi-essential amino acid in humans as endogenous synthesis may not meet total metabolic demands 3

Dosage Recommendations by Indication

1. General supplementation:

   • 3-5 grams per day for adults
   • This dosage has been shown to provide beneficial effects without significant side effects 4

2. Sleep and neurological support:

   • 3 grams before bedtime has shown benefits for sleep quality 2

3. Metabolic health:

   • For metabolic disorders and inflammatory conditions: 5 grams daily 2, 4
   • For potential collagen synthesis support: up to 10 grams daily may be needed 3

4. Research applications:

   • High-dose studies have used 1-5 g/kg/day in animal models 5
   • Human studies typically use lower doses (3-5 g/day) for safety and tolerability

Safety Considerations

Monitoring Parameters

• Normal serum glycine levels are approximately 300 μM
• Therapeutic supplementation can safely increase levels to approximately 900 μM 4
• No significant adverse effects have been observed at recommended supplementation doses

Potential Adverse Effects

• Very high doses may cause transient changes in brain morphology, though no neurotoxic effects were observed even at high doses in animal studies 5
• Excessive intake may theoretically affect NMDA receptor function, though this appears to require extremely high doses 6

Contraindications

• Caution should be exercised in patients with severe liver or kidney disease
• Patients taking medications that affect NMDA receptor function should consult healthcare providers

Clinical Decision Making

When determining glycine dosage:

1. Assess the clinical indication

   • General health support: 3-5 g/day
   • Specific metabolic needs: may require higher doses

2. Consider patient factors

   • Weight and age
   • Renal and hepatic function
   • Concomitant medications

3. Start with lower doses and titrate as needed

   • Begin with 3 g/day
   • Monitor for efficacy and tolerability
   • Increase if needed based on clinical response

4. Divide larger doses throughout the day to improve tolerance

The research suggests that while glycine is synthesized endogenously, dietary intake may be necessary to meet all metabolic demands, particularly for collagen synthesis 3. This supports the concept that glycine supplementation may be beneficial for overall health and specific clinical conditions.