The participants took various probiotic products, including a mix of different bacterial strains, for 3 to 12 months.

The effect sizes on hip and spine BMD, bone formation, and bone resorption were negligible and were neither statistically significant nor clinically significant.

Two trials reported a lower fracture risk in probiotic groups, but fracture risk was very low (1%) in the control groups, so this effect is unlikely to be clinically significant.

There was considerable methodological variability across trials: different strains, multistrain products, and frequent co-supplementation (e.g., calcium, vitamin D, and red clover extract). These are confounding factors that limit the interpretability of the effects.

Probiotics may not improve bone health after menopause Original paper