Table 1.

Links between gut microbiota and magnesium.

Intervention	Study Population	Results	References
Research on animal models
A standard/control diet or a magnesium-deficient diet for 4 or 21 days (500 mg vs. 70 mg mg/kg).	Animal model—8 male C57Bl/6J mice (9 weeks old).	Magnesium-deficient diet reduced abundance of Bifidobacterium, which is associated with systemic inflammation and intestinal inflammation.	Pachikian et al. [156]
A standard/control diet or a magnesium deficient diet for 6 weeks (500 mg vs. 50 mg mg/kg).	Animal model—30 male C57BL/6NBomTac mice (8 weeks old).	Magnesium-deficient diet altered the composition of the gut microbiota and led to depressive-like behaviour.	Winther et al. [157]
Magnesium supplementation in colitis (30 mg vs. 1000 mg vs. 4000 mg mg/kg).	Animal model—27 female C57BL/6 mice (7–8 weeks old).	Increased abundance of Bifidobacterium and reduced abundance of pro-inflammatory Enterobacteriaceae alleviated colitis by modulating the gut microbiota.	Del Chierico et al. [158]
Dietary supplementation with a magnesium-rich marine mineral blend for 6 weeks (standard chow vs. 0.1% MMB-supplemented chow vs. 0.2%-supplemented MMB chow).	Animal model—30 male Sprague Dawley rats (7–8 weeks old).	A significant increase in the diversity of gut microbiota changed the profile of short-chain fatty acids (SCFAs) in the intestines compared to the control group.	Crowley et al. [160]
Studies with humans
Probiotic Lactobacillus reuteri DSM 17938 and magnesium oxide (MgO) for relieving chronic functional constipation in children (group A received L. reuteri DSM 17938 and lactose hydrate as a placebo of MgO; group B received L. reuteri DSM 17938 and MgO; group C received a placebo of L. reuteri DSM 17938 and MgO).	60 children aged from 6 months to 6 years—a double-blind and randomized clinical trial.	L. rueteri DSM 17938 combined with MgO was effective in treating functional constipation and did not disrupt the balance of the intestinal microbiota. MgO by itself suppressed the presence of the Dialister genus and disrupted the balance of the gut microbiota.	Kubota et al. [167]
Personalized magnesium supplementation for the prevention of colorectal cancer.	240 participants—a double-blind factorial randomized controlled trial.	Enhanced gut microbial production of medium-chain fatty acids (MCFAs) which consequently increased plasma MCFAs levels.	Fan et al. [168]