Role of dietary fat in blood pressure control.

Three controlled intervention studies were carried out in North Karelia to study the possible role of dietary fat in the control of human blood pressure. All studies included middle-aged free-living couples (families) and a baseline (BS, 2 weeks), an intervention (IN, 6-12 weeks) and a switch-back (SB, 4-6 weeks) period. During IN the families were instructed to eat low fat (less than 25 en% instead of 39 en%), high P/S ratio diet (0.4-1.1 instead of 0.2). Salt and energy intake and other lifestyles were kept constant. In the first study the P/S ratio of the IN diet was 1.1. Both systolic and diastolic blood pressures decreased significantly during IN and increased back again during SB. The same results were obtained in the second study at P/S level 0.9 when a randomized group with 60% salt reduction and a control had little change in their blood pressure levels. In the third study the blood pressure reduction was again repeated during a 12 week IN period. The reduction was similar in two randomized groups with P/S 0.4 and 0.9, when both group had less than 25 en% of total fat. The results strongly support the hypothesis that dietary fat is related to human blood pressure, and that modification of dietary fat should be considered in the non-pharmacological prevention and management of hypertension.