The essential role of magnesium in immunity and gut health: Impacts of dietary magnesium restriction on peritoneal cells and intestinal microbiome.

Magnesium (Mg) is essential for life, and low levels impair immune function, promote chronic inflammation, and influence the intestinal microbiome, with the peritoneal cavity serving as a site for direct interaction between the cavity and intestinal contents, including the microbiota. This study investigates the effects of a Mg-restricted diet on peritoneal immune cells and its interplay with the intestinal microbiome. Male C57BL/6NTaq mice were divided into three groups: control, restricted, and restored. The control group received a diet containing 500 mg Mg/kg, the restricted group received a diet with 50 mg Mg/kg for four weeks, and the restored group first received the restricted diet for four weeks, followed by the control diet supplemented with 0.5 g MgCl₂ per liter of water for an additional four weeks. Results showed Mg restriction did not affect body weight, food intake, or water consumption but induced hypomagnesemia, reversible upon dietary restoration. Mg deficiency increased in neutrophils numbers in the blood and peritoneal cavity, indicating an inflammatory response. Gene expression analysis in peritoneal mononuclear cells revealed elevated levels of Nfkb, Stat1 and Stat3, suggesting heightened inflammatory signaling. Additionally, cytokine expression analysis showed increased levels of Tnfa, Il1b and Il10, but not Il6, in Mg-restricted group. The intestinal microbiome of Mg-restricted mice exhibited increased alpha diversity, with changes in taxa abundance, including an increase in Romboutsia ilealis and a decrease in the Oscillospiraceae and Lachnospiraceae. Mg deficiency significantly affects some immune functions and gut microbiota, highlighting the importance of Mg² in maintaining the gut health.