Blood pressure change in a free-living population-based dietary modification study in Japan

Objective To assess whether dietary intervention in free-living healthy subjects is effective in improving blood pressure levels. Design Open randomised, controlled trial Setting Free-living healthy subjects in two rural villages in north-eastern Japan. Participants Five hundred and fifty healthy volunteers aged 40-69 years. Interventions Tailored dietary education to encourage a decrease in sodium intake and an increase in the intake of vitamin C and carotene, and of fruit and vegetables. Main outcome measures Blood pressure, dietary intake and urinary excretion of sodium, dietary carotene and vitamin C, and fruit and vegetable intake data were collected at 1 year after the start of the intervention. Results During the first year, changes differed significantly between the intervention and control groups for dietary (P = 0.002) and urinary excretion (P < 0.001) of sodium and dietary vitamin C and carotene (P = 0.003). Systolic blood pressure decreased from 127.9 to 125.2 mmHg (2.7 mmHg decrease; 95% confidence interval, -4.6 to -0.8) in the intervention group, whereas it increased from 128.0 to 128.5 mmHg (0.5 increase; -1.3 to 2.3) in the control This change was statistically significant (P = 0.007). In contrast, the change in diastolic blood pressure did significantly differ between the groups. In subjects, a significant difference in systolic blood reduction was seen between the groups (P = 0.032). Conclusion Moderate-intensity dietary counseling in living healthy subjects achieved significant dietary which resulted in a significant decrease in systolic pressure.