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 group. This change was statistically significant (P = 0.007). In contrast, the change in diastolic blood pressure did not significantly differ between the groups. In hypertensive subjects, a significant difference in systolic blood pressure reduction was seen between the groups (P = 0.032).Conclusion
Moderate-intensity dietary counseling in free-living healthy subjects achieved significant dietary changes, which resulted in a significant decrease in systolic blood pressure.