Salt intake and mental distress among rural community-dwelling Japanese men

Background: Activated mineralocorticoid receptors influence the association between daily salt intake and blood pressure. A relatively low mineralocorticoid receptor function is reported to be a risk for mental distress such as depression. Since mental distress is also a known risk for hypertension and cardiovascular disease, understanding of the association between estimated daily salt intake and mental distress contributing to hypertension is important for risk estimation for cardiovascular disease. However, no single study has reported this association. Methods: We conducted a cross-sectional study of 1014 Japanese men undergoing general health check-ups. Mental distress was diagnosed as a Kessler 6 scale score >= 5. We also classified mental distress by levels of hypertension. Estimated daily salt intake was calculated from a causal urine specimen. Results: Independent from classical cardiovascular risk factors and thyroid disease, we found a significant inverse association between estimated daily salt intake and mental distress. When we analyzed for mental distress and hypertension, we also found a significant association. With the reference group being the lowest tertiles of estimated daily salt intake, the multivariable odds ratios (ORs) of mental distress and mental distress with hypertension for the highest tertiles were 0.50 (0.29-0.88) and 0.46 (0.22-0.96). Conclusions: Lower estimated daily salt intake is a significant risk of mental distress for rural community-dwelling Japanese men. Since depression is reported to be associated with cardiovascular disease, risk estimation for the lower intake of salt on mental distress, especially for mental distress with hypertension, may become an important tool to prevent cardiovascular disease.