Current opinion on the regulation of small intestinal magnesium absorption

Abstract

Magnesium (Mg 2+ ) has an important role in numerous biological functions, and Mg 2+ deficiency is associated with several diseases. Therefore, adequate intestinal absorption of Mg 2+ is vital for health. The small intestine was previously thought to absorb digested Mg 2+ exclusively through an unregulated paracellular mechanism, which is responsible for approximately 90% of total Mg 2+ absorption. Recent studies, however, have revealed that the duodenum, jejunum, and ileum absorb Mg 2+ through both transcellular and paracellular routes. Several regulatory factors of small intestinal Mg 2+ uptake also have been explored, e.g. , parathyroid hormone, fibroblast growth factor-23, apical acidity, proton pump inhibitor, and pH-sensing channel and receptors. The mechanistic factors underlying proton pump inhibitor suppression of small intestinal Mg 2+ , such as magnesiotropic protein dysfunction, higher mucosal bicarbonate secretion, Paneth cell dysfunction, and intestinal inflammation, are currently being explored. The potential role of small intestinal microbiomes in Mg 2+ absorption has also been proposed. In this article, we reviewed the current knowledge on the mechanisms and regulatory factors of small intestinal Mg 2+ absorption.

Mg2+-dependent mechanism of environmental versatility in a multidrug efflux pump

“…Moreover, in the human small intestine, increased luminal acidity enhances Mg 2+ absorption. 18,39 We, therefore, investigated whether Mg 2+ could influence the structural dynamics of AcrA within the two pH regimes (pH 7.4 and pH 6.0) previously tested.…”

“…stomach pH 1.5-4.0 and intestines pH 4.0-7.5) and within the microenvironments of macrophage phagosomes. [15][16][17][18][19] Previous investigations have shown that AcrA conformation is pH-and Mg 2+ -sensitive 16,20,21 and that related heavy metal efflux RND (HME-RND) pump systems -which export metals as part of their function, i.e. Zn 2+ by ZneCAB, and Cu + and Ag + by CusCBA -can interact with the divalent metal cations they export to induce conformational changes.…”

Associations of dietary calcium and magnesium intake with chronic diarrheal symptoms and inflammatory bowel disease: a large cross- sectional study in adults

“…It has also been shown that magnesium, often in the form of laxatives or antacids, are prone to diarrhea [32,33], which should be noted when magnesium is used medicinally. In general, the gastrointestinal symptoms arising under the in uence of magnesium vary, which may be related to the concentrated or dispersed intake of magnesium, the form of intake, and the health status of the individual, whereas exceeding the absorption threshold of magnesium may have a negative impact on the health of humans [34].…”

Case report: Near-fatal hypermagnesemia resulting from the use of Epsom salts in a patient with normal renal function

“…The human body predominantly absorbs magnesium through the paracellular pathway in the jejunum and ileum, accounting for 80–90% of total absorption ( 32 , 33 ). The majority of magnesium in the human body is stored in bones.…”