The causal relationship between gut microbiota and bone mineral density: a Mendelian randomization study

Area of Science:

• Microbiome Research
• Bone Health and Metabolism
• Human Genetics

Background:

• Gut microbiota plays a crucial role in bone health.
• The impact of gut microbiota on bone mineral density (BMD) varies across different life stages.

Purpose of the Study:

• To investigate the causal relationship between gut microbiota and BMD across five distinct age groups using Mendelian randomization.
• To identify specific gut bacteria associated with BMD variations throughout the human lifespan.

Main Methods:

• Mendelian randomization (MR) analysis was performed on five age groups (0-15, 15-30, 30-45, 45-60, 60+ years).
• Three MR methods (MR-Egger, weighted median, inverse-variance weighting) were employed for robust findings.
• Sensitivity analyses, including pleiotropy, heterogeneity, and leave-one-out tests, were conducted.

Main Results:

• Specific gut bacteria were identified as risk or protective factors for BMD in each age group.
• For instance, in the 0-15 group, Eubacterium_fissicatena_group and Eubacterium_hallii_group were risk factors.
• In older adults (60+), Fusicatenibacter and Ruminococcaceae_UCG_002 were risk factors, while Alistipes and Coprococcus_3 were protective.

Conclusions:

• A significant causal link exists between gut microbiota and BMD throughout life.
• The Firmicutes phylum is consistently associated with BMD across age groups.
• Microbiota-BMD associations show stability until age 45, with increased diversity and a shift towards Bacteroidetes in older individuals.