scholarly journals Circulating Alpha-Tocopherol Levels, Bone Mineral Density, and Fracture: Mendelian Randomization Study

Nutrients ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1940
Author(s):  
Karl Michaëlsson ◽  
Susanna C. Larsson

Recent cohort studies indicate a potential role of the antioxidant α-tocopherol in reducing bone loss and risk of fractures, especially hip fractures. We performed a Mendelian randomization investigation of the associations of circulating α-tocopherol with estimated bone mineral density (eBMD) using heel ultrasound and fractures, identified from hospital records or by self-reports and excluding minor fractures. Circulating α-tocopherol was instrumented by three genetic variants associated with α-tocopherol levels at p < 5 × 10−8 in a genome-wide association meta-analysis of 7781 participants of European ancestry. Summary-level data for the genetic associations with eBMD in 426,824 individuals and with fracture (53,184 cases and 373,611 non-cases) were acquired from the UK Biobank. Two of the three genetic variants were strongly associated with eBMD. In inverse-variance weighted analysis, a genetically predicted one-standard-deviation increase of circulating α-tocopherol was associated with 0.07 (95% confidence interval, 0.05 to 0.09) g/cm2 increase in BMD, which corresponds to a >10% higher BMD. Genetically predicted circulating α-tocopherol was not associated with odds of any fracture (odds ratio 0.97, 95% confidence interval, 0.91 to 1.05). In conclusion, our results strongly strengthen a causal link between increased circulating α-tocopherol and greater BMD. Both an intervention study in those with a low dietary intake of α-tocopherol is warranted and a Mendelian randomization study with fragility fractures as an outcome.

2019 ◽  
Vol 106 (2) ◽  
pp. 131-146 ◽  
Author(s):  
Zhiyong Cui ◽  
Xiangyu Meng ◽  
Siying Zhuang ◽  
Zhaorui Liu ◽  
Fang Zhou ◽  
...  

Abstract Until recently, it remains unclear whether schizophrenia, bipolar disorder (BD), and Alzheimer’s disease (AD) is associated with bone mineral density (BMD). We aimed to investigate the causal effects of schizophrenia, BD and AD on BMD with Mendelian randomization (MR) analysis. Single-nucleotide polymorphisms (SNPs) strongly associated with these three neuropsychiatric diseases as instrumental variables were selected from genome-wide association studies in the MR Base database. We analyzed the effects of these SNPs on the femoral neck BMD (FN-BMD), lumbar spine BMD (LS-BMD) and forearm BMD (FA-BMD), and evaluated the heterogeneities and pleiotropy of these genetic variants. We also evaluated the potential confounding factors in the association between these three neuropsychiatric diseases and the BMD level. It was found that none of these genetic variants were significantly associated with BMD or confounding factors. Using these genetic variants, we did not find statistically significant causal effects of per unit increase in the log-odds of having schizophrenia, BD or AD with FN-BMD, LS-BMD and FA-BMD changes (e.g. schizophrenia and FN-BMD, MR-Egger OR 0.9673, 95% CI 0.8382 to 1.1163, p = 0.6519). The MR results also revealed that directional pleiotropy was unlikely to bias the causality (e.g., schizophrenia and FN-BMD, intercept = 0.0023, p = 0.6887), and no evidence of heterogeneity was found between the genetic variants (e.g., schizophrenia and FN-BMD, MR-Egger Q = 46.1502, I2 = 0.0899, p = 0.3047). Our MR study did not support causal effects of increased risk of schizophrenia, BD and AD status with BMD level.


Author(s):  
Shuai Yuan ◽  
Zi-Hao Wan ◽  
Shi-Le Cheng ◽  
Karl Michaëlsson ◽  
Susanna C Larsson

Abstract Context The associations of circulating insulin-like growth factor-1 (IGF-1) levels with bone mineral density and fracture risk are inconclusive in observational studies. Objective We conducted a mendelian randomization study to assess the associations of serum IGF-1 levels with estimated bone mineral density (eBMD) and fracture. Methods Genetic instruments for IGF-1 were selected at the genome-wide significance level (P &lt; 5 × 10–8) from a genome-wide association study including 358 072 individuals of European ancestry. Summary-level data for eBMD (426 824 individuals) and fracture (53 184 fracture cases and 373 611 noncases) were obtained from the UK Biobank study. Univariable and multivariable mendelian randomization analyses methods were used to estimate the associations of IGF-1 with eBMD and fracture. The main outcome measure included the change of eBMD and odds ratio of fracture per genetically predicted 1-SD increase of serum IGF-1 levels. Results For 1-SD increase in IGF-1, the change of eBMD levels was 0.04 g/cm2 (95% CI, 0.01-0.07; P = .011) and the odds ratio of fracture was 0.94 (95% CI, 0.91-0.98; P = .003). The associations persisted with similar magnitude after adjustment for height. The association was consistent for fracture but not for eBMD after excluding genetic instruments that might directly influence these outcomes. The association between IGF-1 and fracture was somewhat attenuated after adjustment for eBMD (odds ratio 0.96; 95% CI, 0.92-0.99; P = .012). Conclusion The present study supports a role for IGF-1 in preventing fracture, possibly and partly mediated by greater bone mineral density.


2013 ◽  
Vol 16 (2) ◽  
pp. 275-278 ◽  
Author(s):  
Lianbing Shen ◽  
Yihua Qiu ◽  
Shunming Xing ◽  
Dechun Chen ◽  
Yazhong Zhu ◽  
...  

2018 ◽  
Author(s):  
Jie Zheng ◽  
Marie-Jo Brion ◽  
John P. Kemp ◽  
Nicole M. Warrington ◽  
Maria-Carolina Borges ◽  
...  

AbstractStatin treatment increases bone mineral density (BMD) and reduces fracture risk, but the underlying mechanism is unclear. We used Mendelian randomization (MR) to assess whether this relation is explained by a specific effect in response to statin use, or by a general effect of lipid-lowering. We utilized 400 single nucleotide polymorphisms (SNPs) robustly associated with plasma lipid levels and results from a heel BMD GWAS (derived from quantitative ultrasound) in 426,824 individuals from the UK Biobank. We performed univariate and multivariable MR analyses of low-density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and triglyceride levels on BMD. To test whether the effect of statins on BMD was mediated by lowering lipid levels, MR was repeated with and without SNPs in theHMGCRregion, the gene targeted by statins. Univariate MR analyses provided evidence for a causal effect of LDL-C on BMD (β= −0.060; −0.084 to −0.036; P = 4×10-6; standard deviation change in BMD per standard deviation change in LDL-C, with 95% CI), but not HDL or triglycerides. Multivariable MR analysis suggested that the effect of LDL-C on BMD was independent of HDL-C and triglycerides, and sensitivity analyses involving MR Egger and weighted median MR approaches suggested that the LDL-C results were robust to pleiotropy. MR analyses of LDL-C restricted to SNPs in theHMGCRregion showed similar effects on BMD(β= −0.083; −0.132 to −0.034; P = 0.001) to those excluding these SNPs (β= −0.063; −0.090 to −0.036; P = 8×10-6). Bidirectional MR analyses provided some evidence for a causal effect of BMD on plasma LDL-C levels. Our results suggest that effects of statins on BMD are at least partly due to their LDL-C lowering effect. Further studies are required to examine the potential role of modifying plasma lipid levels in treating osteoporosis.


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