What is the best absorbed and tolerated daily oral magnesium supplement formula?

From the Guidelines

Magnesium oxide (MgO) is the best absorbed and best tolerated daily oral magnesium supplement formula, with a recommended dose of 500 mg/d to 1 g/d, as it has been evaluated in RCTs and has shown to be effective in exerting a beneficial effect on constipation-related symptoms. When considering the best magnesium supplement, several factors come into play, including absorption, tolerance, and efficacy.

• The bioavailability and clinical efficacy of other formulations of magnesium, such as citrate, glycinate, lactate, malate, and sulfate, are unknown, as only MgO has been evaluated in RCTs 1.
• MgO creates an osmotic gradient in the GI tract, leading to net secretion of water and electrolytes, which can help alleviate constipation-related symptoms 1.
• The available data suggest no increased reports of diarrhea with MgO compared with placebo, making it a well-tolerated option 1.
• Systemic regulation of magnesium levels is maintained by renal excretion, and hypermagnesemia is more likely to occur in individuals with significant renal impairment, so magnesium supplements should be avoided in those with a creatinine clearance of <20 mg/dL 1.
• It is essential to note that the dose of MgO used in trials was 1.5 g/d, but lower doses of 500 mg/d to 1 g/d are often used in clinical practice and may be effective while minimizing potential side effects 1.
• When taking magnesium supplements, it is crucial to start with a lower dose and gradually increase to the full recommended amount to allow the body to adjust and minimize potential stomach upset.
• Additionally, taking the supplement with food can further improve absorption and reduce potential stomach upset.
• Overall, MgO is an attractive first-line option for individuals due to its efficacy, tolerability, availability, and low cost, but it is essential to consider the limitations, including the small number of clinical trials and the lack of long-term effectiveness or harms data 1.

From the FDA Drug Label

Directions shake well before using drink a full glass (8 ounces) of liquid with each dose may be taken as a single daily dose or in divided doses adults and children 12 years of age and over - 6.5 to 10 fl oz maximum 10 fl oz in 24 hours When using this product DO NOT EXCEED RECOMMENDED DOSE.

The best absorbed and best tolerated daily oral magnesium supplement formula cannot be determined from the provided information.

• Magnesium citrate and magnesium malate are both oral magnesium supplements, but the labels do not provide information on their absorption or tolerance compared to each other 2, 3.
• The labels only provide dosage instructions for magnesium citrate and a warning not to exceed the recommended dose for magnesium malate.
• There is no direct comparison or information on which formula is better absorbed or tolerated.

From the Research

Best Absorbed Magnesium Supplement

• Magnesium citrate is found to be more bioavailable than other magnesium preparations in a randomised, double-blind study 4
• Magnesium citrate led to the greatest mean serum magnesium concentration compared with other treatments following both acute and chronic supplementation 4
• Magnesium malate levels remained high for an extended period of time in the serum, and had the highest area under the curve calculation 5

Best Tolerated Magnesium Supplement

• Magnesium citrate malate (MgCM) is proposed to be used in food supplements that are intended to provide up to 300-540 mg/day magnesium, and the data provided demonstrate that the production process results in batches of MgCM that comply with the product specifications and that the product is stable throughout its proposed shelf life 6
• The human studies provided demonstrate that magnesium from MgCM is bioavailable, but the extent of its bioavailability per se or compared to other magnesium sources cannot be established due to the lack of an appropriate magnesium source as a comparator in the studies provided or relevant kinetic data for magnesium 6

Comparison of Different Magnesium Compounds

• Magnesium acetyl taurate was rapidly absorbed, able to pass through to the brain easily, had the highest tissue concentration level in the brain, and was found to be associated with decreased anxiety indicators 5
• Magnesium oxide and magnesium citrate had the lowest bioavailability when compared to the control group 5
• The absorption of organic magnesium compounds is better than absorption of inorganic compounds 7