From the Research
Oral magnesium supplements typically begin to increase serum magnesium levels within 4-8 hours after starting supplementation, as evidenced by a study where serum magnesium was measured 4 and 8 hours after participants ingested 2 supplemental tablets (250 mg magnesium) or 2 placebo tablets 1.
Key Findings
- The study found that more than 75% of trial participants presented with suboptimal serum and RBC magnesium status at baseline, highlighting the need for magnesium supplementation 1.
- RBC magnesium increased 6% and 30% over 30 and 90 days, respectively, suggesting magnesium absorption and uptake into red blood cells over time 1.
- Overall symptomatology, assessed through a magnesium status questionnaire, improved 28% over 30 days and 63% over 90 days 1.
Important Considerations
- Serum magnesium levels don't always accurately reflect total body magnesium stores, as only about 1% of total body magnesium is in the bloodstream 2.
- Factors that can affect absorption include kidney function, gastrointestinal disorders, and concurrent medications like proton pump inhibitors 2.
- Regular monitoring of serum magnesium levels is recommended when initiating supplementation, particularly in patients with impaired kidney function 2.
Recommendations
- Patients should take oral magnesium supplements with food to minimize gastrointestinal side effects like diarrhea.
- Common oral magnesium supplements include magnesium oxide, magnesium citrate, and magnesium glycinate, with typical dosing ranging from 200-400 mg of elemental magnesium daily, often divided into 2-3 doses.
- For patients with normal kidney function, magnesium citrate and glycinate are generally better absorbed than magnesium oxide.