Effect of Dietary Synbiotics on Weightlessness‐Induced Bone Loss

Mitigating weightlessness‐induced bone loss is critical for maintaining functionality in astronauts. The objective of this study was to test the effectiveness of dietary synbiotics (probiotics + prebiotics) in reducing bone loss in a rat model of simulated weightlessness. The experiment followed a 2x2 factorial design with forty rats randomly assigned to a weight [hindlimb‐unloaded (HLU) or control] and diet (synbiotic or control) condition. Twenty rats were HLU for 14 d followed by 14 d of reambulation. Bone structure parameters were measured at endpoint using microcomputed tomography. Statistical analysis utilized generalized linear mixed models. Results showed significant (P<0.05) beneficial effects of synbiotics on femur volume, surface area, and trabecular spacing and pattern. The interaction of diet*weight condition was significant (P<0.05) for multiple measures of cortical bone and showed a protective effect of synbiotics. Measurements of humerus, an intra‐individual control bone, did not differ across groups. These results provide evidence supporting dietary synbiotics as a protective treatment against weightlessness‐induced bone loss. Funded by NASA Idaho Space Grant Consortium.