The Association of Dietary and Urinary Sodium With Bone Mineral Density and Risk of Osteoporosis: A Systematic Review and Meta-Analysis

Objective: Although some earlier studies have indicated an association between dietary/urinary sodium and bone mass density (BMD), bone mass content (BMC), and the risk of osteoporosis (OS), findings are still conflicting. The aim of this study was to summarize the relation of dietary/urinary sodium with BMD, BMC, and the risk of OS.

Methods: We conducted a systematic search up to April 2017 in PubMed/MEDLINE, SCOPUS, and Web of Science to find relevant studies. Articles with cross-sectional and cohort designs in which odds ratios (ORs), correlations (r), or beta coefficients were reported for the association between dietary/urinary sodium and OS, BMD, or BMC were included.

Results: Pooling 11 effect sizes with a total of 39,065 people showed that higher sodium consumption significantly increased the risk of OS (OR = 1.20; 95% confidence interval [CI], 1.02–1.41; p = 0.026), with high heterogeneity among studies (I² = 68.0%; p = 0.001). Subgroup analyses showed significantly higher risk of OS in premenopausal women (OR = 1.31; 95% CI, 1.01–1.69; p = 0.036), in participants with a mean age older than 50 years (OR = 1.15; 95% CI, 1.04–1.28; p = 0.005), in dietary sodium intake subgroup (OR = 1.45; 95% CI, 1.19–1.77; p < 0.001), and in individuals with adjustment for energy (OR = 1.77; 95% CI, 1.38–2.27; p < 0.001). The correlation coefficients showed no significant association between urinary sodium and BMD (r = ?0.46; 95% CI, ?0.74 to ?0.18; p = 0.02).

Conclusions: We found a positive association between sodium intake and the risk of OS, while no association was found with urinary sodium. Furthermore, there was no significant correlation between sodium intake and BMD. Due to high heterogeneity in this research, more studies are suggested.     

Increased level of cathelicidin (LL-37) in vitiligo: Possible pathway independent from vitamin D receptor gene polymorphism

Vitiligo is a multifactorial skin disease with established role of genetics and autoimmunity in its pathogenesis. Vitamin D receptor (VDR) polymorphisms have been suggested to correlate with risk of vitiligo in some ethnic populations. On the other hand, cathelicidin, one of the innate immune system components, has a role in development of some chronic skin diseases and VDR regulates the expression of cathelicidin. We aimed to determine the plasma level of cathelicidin and its association with the VDR gene polymorphisms as well as plasma vitamin D level in patients with vitiligo. Ninety vitiligo patients and 90 non-vitiligo controls participated in this study. Blood levels of 25(OH) vitamin D and cathelicidin were determined with ELISA. Genotyping for VDR polymorphisms (ApaI, TaqI, FokI and BsmI) was done with RFLP-PCR method. Mean blood level of cathelicidin was significantly higher in vitiligo patients as compared to controls (P < .0001). Mean blood level of vitamin D was significantly lower in patients than controls (P = .01). Statistically significant differences were not observed for both genotype and allele frequencies of BsmI, ApaI and TaqI polymorphisms. There was a borderline increased risk of vitiligo in over-dominant model of FokI polymorphism with OR = 1.8 and P = .051. Our findings was suggestive of the potential role of cathelicidin in the pathogenesis of vitiligo; however, future evaluations are needed to determine its precise mechanism. Genetic study of VDR gene polymorphism was suggestive of increased risk of vitiligo in association with a FokI polymorphism in Iranian population.