Sweltering weather may be a blessing in osteoporosis
Exposure to warm weather has the potential to prevent bone loss and fractures, with a recent study showing that it can improve bone strength in adulthood and prevent osteoporosis in mice.
A team of researchers investigated whether heat applied postdevelopmentally in healthy and during osteoporotic states would exert positive effects on bone strength. They conducted a human metadata analysis on the incidence of hip fractures per capita and country worldwide.
Results revealed an inverse association between average temperature and hip fracture incidence. This was independent of vitamin D and calcium levels.
To further investigate, the team housed a group of mice at 34 °C and another group at room temperature for 8 weeks. Interestingly, exposure to warm temperature prevented ovariectomy-induced bone loss in adult female and young male mice. This benefit was attributed to increased trabecular bone volume, connectivity density, and thickness, leading to improved biomechanical bone strength—an effect that was not related to food intake.
Additionally, in ovariectomized mice (an osteoporosis model), exposure to warm temperature after surgery prevented the bone loss observed in controls housed at room temperature.
Combinatorial metagenomics/metabolomics analysis showed that warmth could boost bacterial polyamine biosynthesis, leading to higher total polyamine levels in vivo. Spermine and spermidine supplementation appeared to enhance bone strength, whereas inhibiting polyamine biosynthesis in vivo curbed the beneficial effects of warm temperature on the bone.
Additional investigation should inform the possibility of using warm temperature exposure as a treatment option for osteoporosis.