From the Guidelines
Powdered magnesium is generally more effective than tablet form due to its superior absorption and tolerance, as evidenced by studies suggesting that liquid or dissolvable magnesium products are usually tolerated better than pills. When taken as a powder mixed in liquid, magnesium bypasses some of the digestive barriers that tablets face, allowing for faster and more complete absorption into the bloodstream 1. Common powdered forms include magnesium citrate, glycinate, or malate, which typically offer 200-400mg of elemental magnesium per serving. For optimal results, mix the powder thoroughly in water or juice and consume with food to minimize potential digestive discomfort.
The improved absorption of powdered magnesium is particularly beneficial for addressing magnesium deficiency, muscle cramps, or sleep issues. However, powdered magnesium often has a stronger taste and requires preparation, while tablets offer convenience. If you choose powder, start with a lower dose (around 200mg) and gradually increase as needed to avoid digestive side effects like loose stools. It is essential to note that the dosage of magnesium should be initiated at the recommended daily allowance (350 mg daily for women; 420 mg daily for men) and increased gradually, according to tolerance, because of the possible occurrence of gastrointestinal tract intolerance, muscle weakness, flushing, hypotension, bradycardia, blurred vision, and cognitive effects associated with over-supplementation 1.
Some studies suggest that magnesium oxide (MgO) dosing of 1.5 g/d can exert a beneficial effect on constipation-related symptoms, but the bioavailability and clinical efficacy of other formulations of magnesium for this condition are unknown 1. Systemic regulation of magnesium levels is maintained by renal excretion, and hypermagnesemia is more likely to occur in individuals with significant renal impairment, making it crucial to avoid magnesium supplements in those with a creatinine clearance of <20 mg/dL 1.
In terms of efficacy, the combination of efficacy, tolerability, availability of OTC, and low cost make MgO an attractive first-line option for individuals with chronic idiopathic constipation (CIC) 1. However, limitations to consider include the small number of clinical trials and included participants with CIC, all trials being conducted in Japan, formulations other than MgO not being evaluated, the dose of MgO used in trials being higher than that typically used in clinical practice, and no long-term effectiveness or harms data being available 1.
Overall, the use of powdered magnesium is recommended due to its superior absorption and tolerance, but it is crucial to initiate treatment at the recommended daily allowance and gradually increase the dose as needed, while also considering the potential risks and limitations associated with magnesium supplementation.
From the Research
Magnesium Bioavailability
- The bioavailability of magnesium varies depending on the form of preparation, with some studies suggesting that organic forms such as citrate and amino-acid chelate have greater absorption than inorganic forms like oxide 2, 3.
- A study comparing magnesium oxide and magnesium citrate found that magnesium oxide significantly increased intracellular magnesium levels and reduced total cholesterol and LDL cholesterol, while both treatments reduced platelet aggregation 4.
- A systematic review of magnesium bioavailability found that inorganic formulations appear to be less bioavailable than organic ones, and that the percentage of absorption is dose-dependent 5.
Magnesium Preparation Forms
- Magnesium citrate has been shown to have superior bioavailability compared to other forms of magnesium, including oxide and amino-acid chelate 2.
- Magnesium oxide has been found to have relatively poor bioavailability, with a fractional absorption of around 4% 3.
- Organic forms of magnesium, such as citrate and lactate, are preferred by patients and may have greater bioavailability than inorganic forms 6.
Comparison of Magnesium Forms
- A study comparing the bioavailability of different magnesium preparations found that magnesium citrate and amino-acid chelate had greater absorption than magnesium oxide 2.
- Another study found that magnesium oxide had relatively poor bioavailability, but that magnesium chloride, lactate, and aspartate had greater and equivalent bioavailability 3.
- A systematic review found that the bioavailability of magnesium varies depending on the form of preparation and the dose, with organic forms generally having greater bioavailability than inorganic forms 5.