What is magnesium glycinate?

Magnesium Glycinate: Definition and Clinical Properties

Magnesium glycinate is an organic magnesium salt where magnesium is chelated (bound) to the amino acid glycine, creating a highly bioavailable form of magnesium supplementation with superior gastrointestinal tolerability compared to inorganic forms like magnesium oxide. 1, 2

Chemical Composition and Structure

• Magnesium glycinate consists of approximately 93.75% active ingredient, with magnesium bound to glycine molecules 2
• The chelation process creates an octahedral complex with extraordinary water solubility, which enhances absorption in the gastrointestinal tract 3
• Glycine itself is the smallest non-essential amino acid with anti-inflammatory, cytoprotective, and immunomodulatory properties that may contribute additional benefits beyond magnesium delivery 4

Bioavailability and Absorption

• Organic magnesium salts like magnesium glycinate have significantly higher bioavailability compared to inorganic forms such as magnesium oxide or hydroxide 1, 5
• Research demonstrates improved cellular uptake of magnesium glycinate in intestinal cells (CaCo-2 cells) compared to other commonly used magnesium supplements 3
• Magnesium glycinate shows better intestinal permeability and sustained tissue magnesium levels over time, with maximum effect at 3 hours post-administration 6
• Brain magnesium levels increase with amino acid-bound compounds like magnesium glycinate, though the specific tissue distribution varies by formulation 7

Gastrointestinal Tolerability

• Magnesium glycinate causes significantly less gastrointestinal side effects (diarrhea, bloating, abdominal distension) compared to magnesium oxide or citrate 1, 8
• The reduced osmotic effect makes magnesium glycinate the preferred choice when the primary goal is general supplementation rather than treating constipation 1
• For patients who cannot tolerate other oral magnesium formulations without developing loose stools, magnesium glycinate is among the best options for raising blood magnesium levels 8

Clinical Applications

• For general magnesium supplementation (not constipation management), magnesium glycinate is preferred over inorganic forms due to superior bioavailability and tolerability 1, 5
• The American Society of Clinical Oncology recommends oral magnesium glycinate for maintenance therapy after IV correction of hypomagnesemia or for mild deficiency, particularly in patients receiving chemotherapy medications like cisplatin or cetuximab 1
• Magnesium glycinate may help address constipation through mild osmotic properties, though magnesium citrate is more effective for this specific indication due to stronger osmotic effects 1

Dosing Considerations

• Start with the recommended daily allowance (320 mg elemental magnesium for women, 420 mg for men) and increase gradually according to tolerance 1, 5
• Administer at night when intestinal transit is slowest to maximize absorption 5, 8
• Liquid or dissolvable formulations are better tolerated than pills and have fewer gastrointestinal side effects 1, 5

Safety and Contraindications

• Absolutely contraindicated in patients with creatinine clearance <20 mL/min due to risk of life-threatening hypermagnesemia 1, 5
• Patients are at increased risk of developing hypocalcemia after magnesium glycinate treatment, requiring calcium level monitoring 1
• Use with caution in elderly patients, those with heart failure, electrolyte disturbances, or taking medications that may interact with magnesium 1
• Magnesium glycinate may interact with digoxin, diuretics, and other cardiovascular medications, requiring careful monitoring 5

Comparison to Other Magnesium Forms

• Unlike magnesium citrate, which creates a stronger osmotic gradient making it preferable for constipation, magnesium glycinate provides better general supplementation with minimal laxative effect 1
• Magnesium oxide has lower bioavailability and causes more gastrointestinal disturbances, though it has been studied specifically for chronic constipation at doses of 1.5 g/day 1, 5
• The bioavailability differences between different organic magnesium compounds (citrate vs. glycinate) are not definitively established in head-to-head clinical trials, though both are superior to inorganic forms 1