Associations between water iodine concentration and the prevalence of dyslipidemia in Chinese adults: A cross-sectional study

Abstract

Iodine is important in both thyroid function and lipid metabolism. Some studies have explored the effect of thyroid hormones (THs) and urinary iodine concentration (UIC) on serum lipid levels. However, the association between iodine intake and dyslipidemia has not been well established. This study aimed to investigate the relationship between water iodine concentration (WIC) and dyslipidemia, including hypercholesterolemia, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C) and high low-density lipoprotein cholesterol (LDL-C). A cross-sectional survey was conducted involving 409, 390 and 436 adults (≥18 years) from the iodine-deficient (median water iodine, MWI < 10 µg/L), iodine-adequate (MWI between 40 and 100 µg/L) and iodine-excess (MWI > 100 µg/L) areas, respectively. WIC, total cholesterol (TC), triglyceride (TRIG), HDL-C and LDL-C were measured. The prevalence of dyslipidemia were calculated based on the level of WIC using the chi-square method. To further explore whether prevalence was associated with WIC, simple linear regressions and multiple logistic regression models were used. Compared to those with WIC of 40–100 µg/L, a WIC of >100 µg/L was found to be protective associated with against the occurrence of hypertriglyceridemia [adjusted odds ratio (AOR) = 0.649, 95% confidence interval (CI): 0.455–0.924] and low HDL-C (AOR = 0.429, 95% CI: 0.264–0.697). The prevalence of hypertriglyceridemia, low HDL-C and high LDL-C as a function of WIC was found to be an inverted U-shaped association with a zenith at a WIC of 40–100 µg/L. Collectively, our research showed that serum lipid levels are related to WIC. The benefit effect association between WIC and dyslipidemia appears in cases of iodine excess (>100 µg/L).