Table 5.

Examination of causal relationship between BMD-associated metabolites and HTOT-BMD using the bi-directional MR approach

Directions	MR Methods	β	Standard Error	P-value
DA to HTOT-BMD	Simple median	-0.015	0.005	0.001
	Weighted median method	-0.015	0.005	0.001
	IVW	-0.020	0.003	< 0.001
	MR-Egger	-0.024	0.007	< 0.001
	MR-Egger (intercept)	-0.003	0.004	0.441
HTOT-BMD to DA	Simple median	-0.828	0.766	0.280
	Weighted median method	-0.848	0.766	0.268
	IVW	-1.002	0.572	0.080
	MR-Egger	-1.334	2.022	0.509
	MR-Egger (intercept)	0.015	0.085	0.864
GA to HTOT-BMD	Simple median	-0.009	0.006	0.122
	Weighted median method	-0.009	0.006	0.121
	IVW	-0.008	0.004	0.065
	MR-Egger	0.006	0.014	0.677
	MR-Egger (intercept)	-0.005	0.005	0.324
HTOT-BMD to GA	Simple median	-1.906	0.733	0.009
	Weighted median method	-1.847	0.734	0.012
	IVW	-1.662	0.545	0.002
	MR-Egger	-4.493	1.835	0.014
	MR-Egger (intercept)	0.124	0.077	0.106

β is the estimated effect size of the causal association between exposure and outcome. DA to HTOT-BMD is DA (as exposure) and HTOT-BMD (as outcome); HTOT-BMD to DA is HTOT-BMD (as exposure) and DA (as outcome); HTOT-BMD to GA is HTOT-BMD (as exposure) and GA (as outcome); GA to HTOT-BMD is GA (as exposure) and HTOT-BMD (as outcome).

Abbreviations: DA, dodecanoic acid; GA, glycocholic acid; HTOT-BMD, total hip bone mineral density; IVW, inverse-variance weighted; MR, mendelian randomization.