Effect of population-approach programs promoting salt reduction and potassium intake in Japan: the Population-based Sodium/Potassium Improvement Program (PoSPIP).

Reducing sodium intake in populations is essential, but insufficient for preventing and managing high blood pressure, while the importance of increasing potassium intake is overlooked. We investigated the effects of 1-year population-approach programs (2021-2022) promoting salt reduction and potassium intake using urinalysis feedback and food environment improvement. This retrospective observational study included 7649 participants (mean age, 54.0 years; 45.3% women) from 11 municipalities and 4 workplaces. Outcomes in intensive support programs-including urinary sodium, potassium, and sodium-to-potassium (Na/K) ratio measurements with feedback, dietary promotion, and food environment improvement-were compared with standard support programs providing usual health guidance. In linear regression adjusted for demographics, lifestyle factors, and medical history, the reduction in urinary Na/K ratio was greater in the intensive support group (n = 4064) than in the standard support group (n = 3585) (mean difference -0.14 [95% confidence interval, -0.27 to -0.01]). Although estimated potassium intake decreased in both groups, the decline was smaller in the intensive support group (mean difference 31 [12 to 51] mg/day). Estimated salt intake did not differ between the groups. The intensive support group showed greater increases in diastolic blood pressure and high-density lipoprotein cholesterol and smaller increases in blood glucose, as well as greater reductions in hemoglobin A1c and Salt Check Sheet scores. Mean differences between the groups for endpoints were not heterogeneous across intensive support program types. Our findings support the development of hypertension prevention and management strategies that promote healthier dietary behaviors and can be implemented in community and workplace settings, with broad public health applicability.