Influence of Daidzein, Tempeh, and Probiotics on Phosphorus Levels in the Postmenopausal Rat Model

Phosphorus is an essential component of bone and energy metabolism; however, the mechanism involved in the regulation of phosphorus under postmenopausal conditions remains insufficiently understood. Interestingly, the disruption of estrogen status can alter mineral homeostasis. Meanwhile, phytoestrogens and probiotics may offer a non-pharmacological strategy to support mineral homeostasis; nonetheless, evidence of their impact on phosphorus distribution remains limited. Thus, this study aimed to evaluate the effect of daidzein, tempeh, and Lactobacillus acidophilus on phosphorus distribution in ovariectomized (OVX) rats.

A total of 64 female Wistar rats were allocated to sham-operated (n = 8) or OVX (n = 56) groups. Following a three-week calcium-deficient diet, the OVX rats were randomized to seven dietary interventions for six weeks: control (O), alendronate (OB), daidzein (10 mg/kg diet/day; OD), tempeh (250 g/kg diet/day; OT), probiotic L. acidophilus (1 × 10¹⁰ CFU/day; OL), daidzein + probiotic (ODL), or tempeh + probiotic (OTL). Food intake, body mass, and phosphorus concentrations in feces, the femur, kidney, pancreas, spleen, heart, and liver were analyzed.

OVX groups (O, 366 ± 14 g; p = 0.01; OD, 361 ± 18 g; p = 0.02; OL, 358 ± 29 g; p = 0.04) gained significantly more body mass than sham controls (311 ± 30 g). Dietary interventions with daidzein, tempeh, and L. acidophilus enhanced phosphorus deposition in the femur, kidney, and pancreas compared with the OVX controls. The OT group showed the highest femoral phosphorus levels (178,111 ± 32,628 mg/kg d.w., p = 0.02), while the ODL group revealed elevated phosphorus levels in the kidney (12,966 ± 462 mg/kg d.w.; p = 0.01). The OD (914 ± 115 mg/kg d.w.; p < 0.001), ODL (913 ± 39 mg/kg d.w.; p < 0.001), and OTL (926 ± 70 mg/kg d.w.; p < 0.001) groups showed significantly increased levels of pancreatic phosphorus. A positive correlation was noted between the pancreatic and femoral phosphorus levels (r = 0.33; p = 0.02). Alendronate treatment had no significant effect.

Dietary daidzein, tempeh, and probiotics modulate phosphorus distribution in postmenopausal rats. These results support the translational potential of dietary bioactives to improve phosphorus metabolism in postmenopausal women.