Magnesium Oxalate: Not a Recommended Supplement
Magnesium oxalate is not a recommended form of magnesium supplementation and is not used clinically due to its potential to contribute to kidney stone formation.
Appropriate Magnesium Supplements
- Magnesium oxide is the preferred oral magnesium supplement, containing approximately 60% elemental magnesium, typically administered as 4 mmol (160 mg) capsules with total daily doses of 12-24 mmol 1
- For general health maintenance, the Recommended Dietary Allowance (RDA) for magnesium is 320 mg/day for women and 420 mg/day for men 2
- Magnesium supplementation should not exceed the Tolerable Upper Intake Level of 350 mg/day from supplements to avoid adverse effects 2
Oxalate Concerns and Kidney Stone Risk
- Patients with calcium oxalate stones should limit intake of oxalate-rich foods and maintain normal calcium consumption to reduce stone formation risk 3
- Oxalate is a major component of kidney stones, and increased urinary oxalate is associated with higher risk of stone formation 3
- Magnesium oxalate could potentially contribute to oxalate load, unlike therapeutic magnesium supplements such as magnesium oxide, citrate, or aspartate 2
Recommended Magnesium Formulations
- Organic magnesium salts (aspartate, citrate, lactate) have better bioavailability than magnesium oxide or hydroxide 2
- For chronic idiopathic constipation, magnesium oxide is recommended at doses of 400-500 mg daily 1
- Liquid or dissolvable forms of magnesium are generally better tolerated than pills 2
Special Considerations for Kidney Stone Patients
- Potassium-magnesium citrate has been shown to effectively prevent recurrent calcium oxalate stones, reducing risk of recurrence by 85% in clinical trials 4
- Magnesium oxide alone has not shown significant beneficial effects on calcium oxalate crystallization in short-term human studies 5
- However, animal studies suggest magnesium oxide may help prevent calcium oxalate nephrolithiasis by increasing urinary pH and modestly increasing urinary citrate excretion 6
Administration Recommendations
- Oral magnesium is best administered at night when intestinal transit is slower, allowing more time for absorption 1
- For patients with short bowel syndrome, magnesium oxide is commonly given as 12-24 mmol daily 2
- Divided doses throughout the day may help maintain stable magnesium levels 2
Precautions and Contraindications
- Avoid magnesium supplementation in patients with renal insufficiency due to risk of hypermagnesemia 2
- Common side effects include diarrhea, abdominal distension, and gastrointestinal intolerance 2
- Monitor for signs of magnesium toxicity, including hypotension, bradycardia, and respiratory depression 2
Conclusion
Magnesium oxalate is not used clinically as a supplement. For patients requiring magnesium supplementation, magnesium oxide, citrate, or other formulations should be used instead, with dosing based on the specific clinical indication and patient factors.