Introduction: Excess body fat disturbs the delicate balance of calcium in the body by influencing parathyroid hormone (PTH) levels and vitamin D metabolism, often leading to lower magnesium levels. Recent research suggests that single-strain probiotics can positively influence gut health and mineral balance in obese individuals. Yet, the potential of multi-strain probiotics in addressing these issues among obese postmenopausal women remains largely unexplored. This study seeks to uncover how multi-strain probiotic supplementation, administered at varying doses, impacts magnesium and calcium metabolism in this specific demographic.

Materials and Methods: Three groups of postmenopausal women with obesity, comprising 30 subjects each, received a nine-strain oral probiotic supplement in a daily dose of 2.5×10⁹colony forming units (CFUs) in the low dose (LD) group, 1×10¹⁰ CFUs in the high dose (HD) group, or a placebo for 12 weeks. The probiotic mixture contained bacterial strains (Bifidobacterium bifidum W23, B. lactis W51, B. lactis W52, Lactobacillus acidophilus W37, L. brevis W63, L. casei W56, L. salivarius W24, Lactococcus lactis W19, and Lc. lactis W58) in equal parts. The excipient was composed of maize starch and maltodextrins. The placebo group received the excipient alone packed in identical sachets.

Samples were washed in acetone and deionized water, dried at 105–110 °C, and weighed; permed or dyed hair was excluded. The Ca and Mg contents of hair and serum were determined after digestion in 65% spectra pure HNO3 using a Microwave Digestion system, followed by measurement with flame atomic absorption spectrometry. The accuracy of the method was verified using certified reference materials, achieving a 95%–98% accuracy for Ca and 99%–103% for Mg.

Results: Following the intervention, both supplemented groups exhibited elevated magnesium (Mg) levels in their hair compared to the placebo group. Conversely, hair calcium (Ca) content was higher in the placebo group compared to the low dose (LD) group post-intervention. Serum Mg concentration was notably higher in the LD group but lower in the high dose (HD) group compared to the placebo. Serum Ca concentration in the LD group was lower than that observed in both the placebo and HD groups post-intervention. Additionally, hair Ca content was significantly reduced compared to the HD group following the intervention.

Conclusion: This study indicates a clear impact of probiotic supplementation on Mg levels, as well as more nuanced effects on Ca levels, which are more complex and dosage-dependent.