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

OBJECTIVETo assess whether dietary intervention in free-living healthy subjects is effective in improving blood pressure levels. DESIGNOpen randomised, controlled trial. SETTINGFree-living healthy subjects in two rural villages in north-eastern Japan. PARTICIPANTSFive hundred and fifty healthy volunteers aged 40–69 years. INTERVENTIONSTailored 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 MEASURESBlood 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. RESULTSDuring 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). CONCLUSIONModerate-intensity dietary counseling in free-living healthy subjects achieved significant dietary changes, which resulted in a significant decrease in systolic blood pressure.