Higher serum 25(OH)D concentration is associated with lower risk of metabolic syndrome among Aboriginal and Torres Strait Islander peoples in Australia

TL;DR

This study found that higher serum vitamin D levels are linked to a lower risk of metabolic syndrome among Aboriginal and Torres Strait Islander peoples in Australia, suggesting vitamin D sufficiency could improve metabolic health.

Contribution

First investigation of the association between serum 25(OH)D levels and metabolic syndrome in this Indigenous population group.

Findings

Each 10 nmol/L increase in serum 25(OH)D reduces metabolic syndrome risk by 16%.

Higher serum 25(OH)D is associated with smaller waist circumference.

Inverse association between serum 25(OH)D and most metabolic risk factors.

Abstract

Although previous observational studies have shown associations between serum 25-hydroxyvitamin D (25(OH)D) concentration and metabolic syndrome, this association has not yet been investigated among Aboriginal and Torres Strait Islander peoples. We aimed to investigate the association between serum 25(OH)D concentration and metabolic syndrome and its risk factors in this population group. We used cross-sectional data from the 2012-2013 Australian Aboriginal and Torres Strait Islander Health Survey. Metabolic syndrome is defined as having 3 or more risk factors: elevated waist circumference, elevated triglycerides, low high-density lipoprotein (HDL) cholesterol, elevated blood pressure, or elevated fasting blood glucose. We used binomial logistic regression to test associations between serum 25(OH)D concentration and metabolic syndrome, and multiple linear regression to test associations between serum 25(OH)D concentration and each risk factor. We included the following covariates: age, sex, smoking status, education level, socio-economic status, remoteness of location, season, and body mass index (BMI). After adjusting for covariates, we found that each 10 nmol/L increase in serum 25(OH)D concentration was statistically significantly associated with a 16% lower risk of metabolic syndrome (odds ratio: 0.84, 95% confidence interval: 0.76, 0.92) and a 2.1 cm (95% confidence interval: 1.65, 2.57) lower waist circumference (BMI was not included in the model for waist circumference). We found small inverse associations between serum 25(OH)D concentration and all other risk factors except systolic blood pressure. Given that higher serum 25(OH)D concentration may confer metabolic health benefits, promoting vitamin D sufficiency may be beneficial for this population.