Excessive salt intake is a significant predictor for future development of metabolic syndrome in the general population

Abstract

Abstract Background/Introduction Dietary salt consumption is one of the most important modifiable factors in our lifestyle and restriction of dietary salt results in the reduction of blood pressure in previous studies. Excessive salt intake causes cardiovascular diseases independently of its effects on blood pressure. Since metabolic syndrome also increases a risk of cardiovascular disease, there may be some association between salt intake and metabolic syndrome. Purpose The present study was designed to investigate a possible relationship between salt intake and future development of metabolic syndrome in the general population. Methods Consecutive 12,256 subjects without metabolic syndrome (male=7,053, 52.1±12.3 year-old) who visited our hospital for an annual physical check-up from April 2010 to March 2018 were enrolled. After baseline examination, subjects were followed up until March 2019 (median 1,582 days) with the endpoint being the development of metabolic syndrome. Metabolic syndrome was diagnosed according to the Japanese criteria (2005). Individual salt intake was estimated using a spot urine by a previously reported method. Results Salt intake was 11.9±3.0 g/day in male and 8.2±2.1 g/day in female subjects at baseline. During the follow-up period, 1,669 subjects developed metabolic syndrome (29.9 per 1,000 person-year) with the incidence being more frequent in male than female subjects (41.8 vs. 14.2 per 1,000 person-year). Non-adjusted hazard ratio (HR) (95% confidence interval [CI]) of salt intake for the development of metabolic syndrome was 1.157 (1.142–1.173). In analysis where subjects were divided into gender-specific quartiles according to the baseline salt intake, Kaplan-Meyer curve analysis revealed that the incidence of metabolic syndrome were increased across the quartiles (20.6, 25.0, 32.4, and 42.7 per 1,000 person-years; logrank p<0.001). Multivariate Cox proportional hazard analysis adjusted for age, gender, body mass index, systolic blood pressure, heart rate, serum creatinine, uric acid, fasting plasma glucose, low-density lipoprotein cholesterol, triglyceride, hemoglobin and current smoking habit at baseline revealed that salt intake predicted the new onset of metabolic syndrome (HR: 1.036, 95% CI: 1.019–1.054). Conclusions Excessive salt intake is significantly associated with the new development of metabolic syndrome in the general population. The results suggest that salt restriction prevents metabolic syndrome as well as hypertension leading to cardiovascular diseases. Funding Acknowledgement Type of funding source: None