From the Guidelines
Magnesium oxide is the most commonly given form of magnesium for oral absorption, containing more elemental magnesium than other salts, and is typically administered as gelatine capsules of 4 mmol magnesium oxide (160 mg of MgO) to a total of 12–24 mmol daily. According to the guidelines for management of patients with a short bowel 1, magnesium oxide is preferred due to its high elemental magnesium content and solubility in dilute acid, which allows for conversion to magnesium chloride in the stomach. This form of magnesium is often given at night to take advantage of slower intestinal transit and potentially improve absorption. While other forms of magnesium, such as magnesium glycinate, malate, and taurate, may be well-absorbed, the provided evidence does not support their use over magnesium oxide in this context. Key considerations for oral magnesium supplementation include:
- Starting with a lower dose and gradually increasing to assess tolerance
- Monitoring serum magnesium levels to adjust dosage as needed
- Avoiding excessive doses to prevent gastrointestinal side effects, such as diarrhea
- Considering alternative forms of magnesium, like magnesium glycinate, if gastrointestinal discomfort occurs with magnesium oxide. However, the evidence from 1 suggests that magnesium oxide is a suitable and commonly used option for oral magnesium supplementation.
From the FDA Drug Label
ACTIVE INGREDIENT Magnesium Glycinate: ~93.75% Active Ingredient Magnesium citrate 1.745g per fl oz The best form of magnesium for oral absorption is not explicitly stated in the provided drug labels.
- Magnesium glycinate and magnesium citrate are two different forms of magnesium, but the labels do not compare their absorption rates or provide information on which one is better absorbed orally 2 3. No conclusion can be drawn about the best form of magnesium for oral absorption based on the provided information.
From the Research
Magnesium Bioavailability
The bioavailability of magnesium from different compounds has been studied in various research papers.
- Magnesium malate and magnesium acetyl taurate have been found to have higher bioavailability compared to other compounds such as magnesium oxide and magnesium citrate 4.
- Magnesium acetyl taurate was rapidly absorbed and had the highest tissue concentration level in the brain, and was found to be associated with decreased anxiety indicators 4.
- Magnesium malate levels remained high for an extended period of time in the serum 4.
Comparison of Magnesium Compounds
- A study compared the bioavailability of magnesium from magnesium citrate and magnesium oxide, and found that magnesium citrate was more soluble and bioavailable than magnesium oxide 5.
- Another study found that magnesium from effervescent tablets had better bioavailability than from capsules 6.
- The bioavailability of magnesium from different pharmaceutical formulations has been found to vary, with some compounds having higher bioavailability than others 6, 5.
Magnesium and Sleep/Anxiety
- Some studies have found that magnesium supplementation can improve sleep quality and reduce anxiety symptoms 7, 8.
- However, the evidence is not conclusive, and more research is needed to confirm the effectiveness of magnesium supplementation for sleep and anxiety disorders 7, 8.
- The optimal form and dosage of magnesium for sleep and anxiety disorders is not established, and further research is needed to determine the most effective treatment 7.