Magnesium absorption and solubility
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Magnesium Absorption and Solubility: Key Factors
Solubility of Magnesium Salts and Its Impact on Absorption
The solubility of magnesium salts is a major factor influencing how well magnesium is absorbed in the body. Organic magnesium salts, such as magnesium citrate, bisglycinate, and glycerophosphate, are much more soluble in water and in simulated digestive conditions than inorganic salts like magnesium oxide. This higher solubility translates directly into better absorption and bioavailability in humans and animals 12. For example, magnesium citrate is significantly more soluble and leads to a greater increase in urinary magnesium (a marker of absorption) compared to magnesium oxide . Similarly, magnesium bisglycinate and glycerophosphate outperform magnesium oxide in both solubility and absorption efficiency .
Influence of Formulation and Food Matrix
The way magnesium is formulated also affects its solubility and absorption. Enteric-coated magnesium supplements, which are designed to dissolve further down the digestive tract, can actually reduce magnesium absorption compared to more soluble forms like magnesium acetate . In contrast, magnesium from natural food sources such as almonds is as bioavailable as from highly soluble supplements, indicating that the food matrix does not necessarily hinder absorption if the magnesium is in a soluble form . Marine-derived magnesium products, such as Aquamin-Mg, have shown superior solubility during digestion, especially when taken with food, and are well tolerated .
Dietary Interactions Affecting Magnesium Solubility
Other dietary minerals can impact magnesium solubility and absorption. High intakes of calcium and phosphate can decrease magnesium solubility in the intestine by forming insoluble complexes, which in turn reduces magnesium absorption . This effect is particularly pronounced when both calcium and phosphate are present at elevated levels.
Absorption Mechanisms in the Intestine
Magnesium is absorbed in the small intestine through both paracellular (between cells) and transcellular (through cells) pathways. The paracellular route is responsible for the majority of magnesium absorption, but recent research has shown that transcellular absorption also plays a significant role, especially in the colon 910. Factors such as intestinal pH, the presence of certain hormones, and even the gut microbiome can influence these absorption pathways .
Solubility Testing and Predicting Bioavailability
Simple in vitro solubility tests, such as the "Vinegar test" using acetic acid, can reliably rank the quality of inorganic magnesium sources and predict their bioavailability in animals like dairy cattle . These tests help refine dietary formulations by identifying which magnesium sources are most likely to be absorbed efficiently.
Magnesium from Seaweeds and Other Natural Sources
The absorption of magnesium from seaweeds varies depending on the type of seaweed and its fiber content. Some seaweeds, like Kombu and Aosa, provide magnesium that is as absorbable as magnesium oxide, while others may have lower absorption due to their fiber composition. Notably, magnesium solubility alone does not always predict absorption, as the overall absorbable magnesium concentration is also important .
Conclusion
Magnesium absorption is strongly influenced by the solubility of the magnesium source, with organic and highly soluble forms being absorbed more efficiently than poorly soluble inorganic forms. Dietary factors, supplement formulation, and interactions with other minerals can further affect magnesium solubility and absorption. Understanding these factors is crucial for optimizing magnesium supplementation and addressing deficiencies effectively 12345678+2 MORE.
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