What is the preferred form of magnesium supplementation, magnesium citrate or magnesium glycinate?

Magnesium Citrate vs. Magnesium Glycinate: Which Form to Choose

Organic magnesium salts such as magnesium citrate are recommended over inorganic forms like magnesium oxide due to their better bioavailability, though there is insufficient evidence to definitively recommend magnesium citrate over magnesium glycinate for general supplementation. 1

Bioavailability Considerations

• Organic magnesium salts (including citrate, glycinate, aspartate, and lactate) have higher bioavailability compared to inorganic forms like magnesium oxide or hydroxide 1
• The bioavailability differences between different organic magnesium compounds (citrate vs. glycinate) are not well established in clinical trials 1
• Magnesium citrate has been more extensively studied in clinical settings, particularly for constipation management 1

Clinical Applications

Constipation Management

• Magnesium oxide (MgO) has been evaluated in randomized controlled trials for chronic idiopathic constipation and shows significant benefits 1
• Magnesium citrate creates an osmotic gradient in the GI tract that draws water into the intestines, making it particularly effective for constipation 1
• If constipation is the primary concern, magnesium citrate may be preferable due to its stronger osmotic effect 1

Neurological Benefits

• Magnesium glycinate may be better tolerated by those with sensitive digestive systems due to potentially less pronounced laxative effects 2
• Some research suggests amino acid-bound forms like magnesium glycinate may have different tissue distribution patterns than organic acid-bound forms like magnesium citrate 2
• Specialized forms like magnesium L-threonate have shown benefits for cognitive function and sleep, though these are different from standard magnesium glycinate 3, 4

Dosing Considerations

• For general supplementation, spreading magnesium doses throughout the day is recommended rather than taking a single large dose 1
• Magnesium oxide has been studied at doses of 1.5 g/day for constipation, though lower doses of 500 mg to 1 g/day are commonly used in clinical practice 1
• Dividing high doses of magnesium supplements may not significantly increase tissue magnesium levels compared to single dosing 2

Safety Considerations

• Avoid magnesium supplementation in patients with significant renal impairment (creatinine clearance <20 mL/min) due to risk of hypermagnesemia 1
• Magnesium citrate may cause more pronounced gastrointestinal effects (diarrhea, bloating) due to its osmotic properties 1
• Long-term use of magnesium supplements should be monitored to avoid potential gastrointestinal discomfort 5

Clinical Decision Algorithm

1. For constipation predominant issues: Choose magnesium citrate for its stronger osmotic effect 1
2. For patients with sensitive GI systems: Consider magnesium glycinate for potentially less pronounced laxative effects 2
3. For general supplementation: Either form is acceptable, with organic magnesium salts preferred over inorganic forms 1
4. For patients with renal impairment: Avoid all magnesium supplements if creatinine clearance is <20 mL/min 1

Common Pitfalls

• Assuming all magnesium forms are equivalent in bioavailability - organic forms are generally superior to inorganic forms 1
• Using magnesium supplements in patients with significant renal impairment 1
• Expecting immediate results - tissue magnesium levels may take time to normalize 2
• Overlooking the potential laxative effect of magnesium citrate, which may be undesirable in some patients 1