From the Guidelines
To correct hypomagnesemia, the recommended dose of oral magnesium is 350 mg daily for women and 420 mg daily for men, which can be increased gradually according to tolerance. This dose is based on the recommended daily allowance and is supported by a recent study published in the Mayo Clinic Proceedings 1. The study suggests that high doses of oral magnesium (600 to 6500 mg daily) may be effective in improving symptoms, but it also highlights the importance of starting with a lower dose and increasing gradually to avoid gastrointestinal tract intolerance and other side effects.
When supplementing with oral magnesium, it is essential to consider the following factors:
- Divide the daily dose into 2-3 doses throughout the day to improve absorption and reduce gastrointestinal side effects
- Choose a well-absorbed supplement form, such as magnesium citrate or glycinate, which may be better tolerated than magnesium oxide
- Start with a lower dose and gradually increase to minimize digestive issues like diarrhea
- Take supplements with food to improve tolerance
- Monitor serum magnesium levels and adjust the dose accordingly, as individual factors such as kidney function, medication use, and the severity of deficiency can affect the required dose.
It is also important to note that magnesium supplementation can improve various symptoms of deficiency, such as muscle cramps, fatigue, and irregular heartbeat, as it is essential for over 300 enzymatic reactions in the body, including energy production, muscle function, and nervous system regulation 1. Improvement in serum levels typically occurs over 1-2 weeks of consistent supplementation.
From the Research
Magnesium Supplementation for Hypomagnesemia
- The required dose of oral magnesium to correct hypomagnesemia is not explicitly stated in the provided studies, but some studies suggest the following:
- Asymptomatic patients with hypomagnesemia can be treated with oral magnesium supplements 2
- The best recommendation is to increase consumption of magnesium-rich food, and for people who do not get sufficient magnesium from their diet, completing the daily amount with supplements of up to 600 mg/day should be considered 3
- Factors to consider when determining the dose of oral magnesium include:
- Serum magnesium levels: a low serum magnesium is a definite sign of magnesium deficiency, but values within the reference range do not rule out deficiencies 4
- Renal function: patients with chronic kidney disease (CKD) may be at risk of hypermagnesemia when taking oral magnesium oxide 5
- Dietary intake: a combination of a dietary intake <250 mg/day, urinary excretion <80 mg/day, and serum magnesium concentration < 0.85 mmol/L could indicate that an individual would respond to magnesium supplementation 6
Dosage Considerations
- The dosage of oral magnesium oxide associated with hypermagnesemia and high serum magnesium concentration in patients with functional constipation was >1,000 mg/day 5
- The Estimated Average Requirement and Recommended Dietary Allowance for magnesium are 175 and 250 mg/d, respectively, for 70 kg healthy individuals, and increase or decrease based on body weight 6
- Urinary excretion data from balance studies indicate that 40 to 80 mg Mg/day are excreted when magnesium intakes are <250 mg/day, and 80 to 160 mg/day when intakes are >250 mg/day 6
Monitoring and Treatment
- Serum magnesium levels should be checked at least every six months in patients with heart failure, people taking diuretic therapy, and people taking proton-pump inhibitors 3
- Parenteral magnesium should be reserved for symptomatic patients with severe magnesium deficiency (< 1.2 mg/dL) 2
- Establishment of adequate renal function is required before administering any magnesium supplementation 2