Predictors of blood pressure change in a series of controlled dietary intervention studies.

Three controlled dietary intervention studies were carried out in 1981-1983 in North Karelia, Finland, to asses the impact of dietary fat intake modification on blood pressure (BP). All these studies involved middle-aged men and women in rural or semirural areas and comprised a baseline period, a six week (or 12 weeks in the third study) intervention period and a four to six week return to baseline. During the intervention period the total fat intake was reduced from 39% to 24% of energy and the polyunsaturated/saturated (P/S) ratio increased from 0.2 to 0.4-1.2. In all groups energy intake was kept constant. For the present report data from the three studies were pooled for a series of stepwise regression analyses to predict changes in BP with different dietary changes. For both systolic (SBP) and diastolic (DBP) blood pressure, change in polyunsaturated fatty acid intake was the strongest dietary predictor of BP change. Changes in body weight, total fat intake, urinary sodium and potassium did not have significant predictive power in any of the analyses. The findings support the hypothesis that modification of dietary fat intake is a significant predictor of change in BP.