From the Guidelines
Magnesium citrate, magnesium aspartate, magnesium lactate, and other organic salts are considered to have higher bioavailability compared to magnesium oxide or hydroxide. When considering the best absorbed form of magnesium, it's essential to look at the most recent and highest quality studies. According to the study published in Kidney International in 2021 1, organic salts such as magnesium citrate, aspartate, and lactate have higher bioavailability than magnesium oxide or hydroxide.
Key Points to Consider
- The study recommends oral administration of magnesium salts, with a preference for organic salts due to their higher bioavailability 1.
- Magnesium citrate is another well-absorbed option, though it may have a mild laxative effect, as noted in a study published in Gastroenterology in 2014 1.
- Magnesium oxide, on the other hand, has poor absorption rates and should be avoided if possible.
- The American Gastroenterological Association also discusses the role of magnesium in managing constipation, highlighting its osmotic effect in the GI tract, but notes that only magnesium oxide has been evaluated in RCTs for this purpose 1.
Recommendations for Supplementation
- For optimal absorption, consider taking 300-400mg of magnesium citrate or other organic salts daily, divided into 2-3 doses with meals.
- Start with a lower dose and gradually increase to minimize digestive discomfort.
- Absorption is enhanced when taken with vitamin D and reduced when taken with high-fiber meals or calcium supplements.
- Magnesium is essential for over 300 biochemical reactions in the body, including energy production, muscle function, and nervous system regulation, making proper absorption crucial for overall health.
From the FDA Drug Label
Both IV and IM administration are appropriate IM administration of the undiluted 50% solution results in therapeutic plasma levels in 60 minutes, whereas IV doses will provide a therapeutic level almost immediately.
The best absorbed form of magnesium is IV administration, as it provides a therapeutic level almost immediately, whereas IM administration takes 60 minutes to reach therapeutic plasma levels 2.
- Key points:
- IV administration provides immediate therapeutic levels
- IM administration takes 60 minutes to reach therapeutic plasma levels
- No oral form of magnesium is mentioned in the provided drug label as being more effective than IV or IM administration.
From the Research
Magnesium Absorption
The absorption of magnesium varies depending on the form and compound used.
- Organic magnesium compounds have been shown to have better absorption than inorganic compounds 3.
- Magnesium citrate has been found to increase muscle and brain magnesium levels in a dose-independent manner 3.
- Studies have also shown that magnesium citrate has superior bioavailability compared to other magnesium preparations, such as magnesium oxide and amino-acid chelate 4.
Comparison of Magnesium Preparations
Different magnesium preparations have been compared in terms of their bioavailability.
- Magnesium citrate has been found to have greater bioavailability than magnesium oxide and amino-acid chelate 4.
- Magnesium chloride, magnesium lactate, and magnesium aspartate have been shown to have equivalent and higher bioavailability than magnesium oxide 5.
- The bioavailability of magnesium preparations can be measured using methods such as urinary magnesium excretion and renal elimination 6, 7.
Factors Affecting Magnesium Absorption
Several factors can affect the absorption of magnesium, including: