Association between nonalcoholic fatty liver disease and bone mineral density: a systematic review and meta-analysis

Decreased Sclerostin Secretion in Humans and Mice With Nonalcoholic Fatty Liver Disease

Objectives

Growing evidence argues for a relationship between liver and bone metabolisms. Sclerostin is a secreted glycoprotein and could antagonize osteoblast-mediated bone formation. Previous studies indicated that circulating sclerostin levels may be associated with metabolic parameters with inconsistent results. This study was designed to evaluate serum sclerostin in patients with or without nonalcoholic fatty liver disease (NAFLD) and to analyze its relationship with metabolic parameters in different populations.

Methods

A cross-sectional study was designed and 168 NAFLD subjects and 85 control subjects were included in this study. Serum sclerostin and metabolic parameters were measured. Mouse models of NAFLD were also induced by high-fat diet. Bone structural parameters were determined using microCT and mRNA expression levels of sclerostin in bone and liver tissues were measured.

Results

Our study suggested that circulating sclerostin levels were significantly lower in NAFLD subjects compared with normal controls. In NAFLD subjects, sclerostin was negatively correlated with multiple metabolic parameters, including waist circumference, urea, hepatic enzyme, gamma-glutamyl transpeptidase, and triglyceride, while such correlation was not significant in control subjects. Circulating sclerostin was also negatively correlated with fatty liver index in NAFLD subjects but not in control subjects. Mice fed on a high-fat diet had reduced bone mass and lower sclerostin expression levels in both the bone and liver tissues.

Conclusions

Our study suggested that the liver-lipid-bone interactions may play a key role in the abnormal bone metabolism in NAFLD, and circulating sclerostin may be a surrogate marker to reflect bone metabolism status in NAFLD subjects.

The Impact of Nordic Walking on Bone Properties in Postmenopausal Women with Pre-Diabetes and Non-Alcohol Fatty Liver Disease

This study investigated the impact of Nordic walking on bone properties in postmenopausal women with pre-diabetes and non-alcohol fatty liver disease (NAFLD). A total of 63 eligible women randomly participated in the Nordic walking training (AEx, n = 33), or maintained their daily lifestyle (Con, n = 30) during intervention. Bone mineral content (BMC) and density (BMD) of whole body (WB), total femur (TF), femoral neck (FN), and lumbar spine (L2-4) were assessed by dual-energy X-ray absorptiometry. Serum osteocalcin, pentosidine, receptor activator of nuclear factor kappa-B ligand (RANKL) levels were analyzed by ELISA assay. After an 8.6-month intervention, the AEx group maintained their BMC_TF, BMD_TF, BMC_L2−4, and BMD_L2−4, and increased their BMC_FN (p = 0.016), while the Con group decreased their BMC_TF (p = 0.008), BMD_TF (p = 0.001), and BMD_L2−4 (p = 0.002). However, no significant group × time interaction was observed, except for BMD_L2−4 (p = 0.013). Decreased pentosidine was correlated with increased BMC_WB(r = −0.352, p = 0.019). The intervention has no significant effect on osteocalcin and RANKL. Changing of bone mass was associated with changing of pentosidine, but not with osteocalcin and RANKL. Our results suggest that Nordic walking is effective in preventing bone loss among postmenopausal women with pre-diabetes and NAFLD.

Association Between Liver Fat and Bone Density is Confounded by General and Visceral Adiposity in a Community-Based Cohort

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) is associated with low bone mineral density (BMD); however, it is not known whether early-stage NAFLD may be associated with BMD after accounting for BMI or visceral adipose tissue (VAT).

METHODS

This was a cross-sectional study of 3,462 Framingham Heart Study participants who underwent computed tomographic measurement of liver fat, VAT volume, volumetric spine BMD, vertebral cross-sectional area (CSA), and vertebral compressive strength. This study excluded heavy alcohol consumers. Multivariable linear regression models were used to assess the association between NAFLD and volumetric BMD, CSA, and vertebral compressive strength after accounting for covariates, including BMI or VAT.

RESULTS

A total of 2,253 participants (mean age, 51.2  [SD 10.7] years; 51.1% women) were included. In multivariable-adjusted models, positive associations between NAFLD and integral BMD, trabecular BMD, and vertebral compressive strength were observed. However, results were attenuated and no longer significant after additionally adjusting for BMI or VAT. NAFLD was observed to be weakly associated with a lower vertebral CSA in adjusted models.

CONCLUSIONS

In a community-based cohort, the associations between NAFLD and BMD and vertebral strength were confounded by BMI and VAT. However, NAFLD was associated with a reduced vertebral CSA in adjusted models.

Hepatic fat content and bone mineral density in children with overweight/obesity

OBJECTIVES

To examine the influence of non-alcoholic fatty liver disease (NAFLD) and hepatic fat content on bone mineral density (BMD), and to investigate whether the relationship between NAFLD and BMD is independent of lifestyle factors related to BMD.

METHODS

Hepatic fat content (magnetic resonance imaging), BMD, lean mass index, total and abdominal fat mass (dual-energy-X-ray absorptiometry), moderate to vigorous physical activity (MVPA) (accelerometry), and calcium and vitamin D intake (two 24 h recalls) were measured in 115 children with overweight/obesity aged 10.6 ± 1.1 years old.

RESULTS

Children with NAFLD had lower BMD than children without NAFLD regardless of sex, puberty stage, lean mass index, fat mass, MVPA, and calcium and vitamin D intake (0.89 ± 0.01 vs. 0.93 ± 0.01 g/cm² for NAFLD and non-NAFLD, respectively, P < 0.01). Higher hepatic fat content was significantly associated with lower BMD regardless of confounders (adjusted P < 0.05).

CONCLUSIONS

Findings of the current study suggest that hepatic fat accumulation is associated with decreased BMD independently of adiposity, and regardless of those lifestyle factors closely related to bone mineral accrual in children. These results may have implication in the clinical management of children with overweight/obesity given the high prevalence of pediatric NAFLD.

Association between bone mineral density and nonalcoholic fatty liver disease in Korean adults

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is associated with various metabolic abnormalities that can increase the risk of an osteoporotic fracture. Across the few previous studies of the association between NAFLD and bone mineral density (BMD), the association was not consistent. We examined the association between BMD and NAFLD in generally healthy adults.

METHODS

The subjects who visited the Seoul National University Hospital for health checkup between 2005 and 2015 were included. Men aged more than 40 and postmenopausal women were included. Lumbar spine and femoral neck (FN) BMD were measured using dual-energy X-ray absorptiometry. Liver ultrasonography was conducted to evaluate the extent of fatty changes. After excluding subjects with a secondary cause of liver disease such as heavy drinking or viral hepatitis, multivariable linear regression analysis adjusted for possible cofactors was performed to investigate the association between BMD and NAFLD.

RESULTS

A total of 6634 subjects was included in this study (men:women = 3306:3328). Multivariate regression analysis revealed a significant negative association between FN BMD and NAFLD in men (β = -0.013, p = 0.029). However, there was a positive correlation between lumbar spine BMD and NAFLD in postmenopausal women (β = 0.022, p = 0.005).

CONCLUSIONS

Moderate or severe NAFLD exerted a detrimental effect on FN BMD in men. However, moderate or severe NAFLD had a positive effect on lumbar spine BMD in postmenopausal women. Potential sex-specific differences of the effect of NAFLD on BMD need to be elucidated further.