Dairy consumption has a partial inverse association with systolic blood pressure and hypertension in populations with high salt and low dairy diets: cross-sectional data analysis from the Iwaki Health Promotion Project

The prevalence of hypertension in Japan remains high, owing to the high salt content of the typical Japanese diet. Dairy-based foods may reduce blood pressure and hypertension risk. However, dairy consumption is low in Japan, and the relationships between dairy intake and blood pressure or the mechanisms by which dairy products affect blood pressure are not fully understood. This cross-sectional study was conducted as part of the Iwaki Health Promotion Project in Aomori, Japan. A total of 1071 participants were included from those who underwent annual medical checkups in June 2015. Adjusted multivariate linear and logistic regression analyses were performed to analyze the relationships between dairy consumption and blood pressure or hypertension risk. Comprehensive blood biomarker measurements were also performed. Whole- and high-fat dairy consumption was found to have significant inverse associations with systolic blood pressure (SBP) for all participants (beta = -0.0213, P = 0.044) and with SBP and systolic hypertension risk for non-users of antihypertensive medicines (beta = -0.0306, P = 0.011; and OR = 0.9927, P = 0.016; respectively). Three blood biomarkers related to phosphorus metabolism (inorganic phosphorus, intact parathyroid hormone, and interleukin-6) were associated with both dairy consumption and SBP. Dairy consumption had a partial inverse association with SBP and hypertension risk in a Japanese population with high salt and low dairy consumption. Analysis of blood biomarkers suggested that phosphorus metabolism is involved in the associations between dairy consumption and blood pressure.