Effect of dietary fat on blood pressure in a rural Finnish population

Abstract

Thirty couples living in Liperi, a community of North Karelia, aged 40 to 50 yr participated in a dietary intervention study to assess the influence of dietary fat on blood pressure and other parameters. After a weeklong base-line period the subjects consumed a low fat diet (24% of energy) with a polyunsaturated/saturated fat ratio (P/S) of 1.2 for 6 wk. After this 6-wk intervention period the subjects resumed their normal diets (36% energy from fat, P/S 0.15) for an additional 6-wk period. Body weight remained constant throughout the study and salt intakes were approximately 12 g/day. During the low fat, high P/S period a decrease of 7.5 and 2.8 mm Hg pressure occurred for systolic and diastolic blood pressure from the base-line level. When the normal diet was resumed, systolic and diastolic blood pressures increased by 7.7 and 6.3 mm Hg, respectively, from the levels observed at the end of the intervention period.

Lack of effect on blood pressure by low fat diets with different fatty acid compositions

“…The HP diet of the present study was closely similar to the intervention diet of the 1980 study. 24,50 The main difference between the two studies is found in the background diets of the subjects constituting the baseline against which the results of the interventions were compared. In 1980 the subjects habitually consumed a diet with 39 en% fat and 3.2 en%, PUFA.…”

“…24,25,29 We excluded hypertensive individuals and those with low BP levels unless the spouse fulfilled the criteria for recruitment. At screening a large proportion of the participants were borderline hypertensive, but both SBP and DBP levels showed a tendency to decline after screening and during the baseline period.…”

“…48 In 1980-1981 three consecutive trials with fatmodified diets were conducted among groups of middle-aged inhabitants of the North Karelia Province in eastern Finland. 24,25,29 The results suggested that an increase in the intake of linoleic acid with or without concomitant reduction in total fat intake reduced BP. In view of the conflicting results of other studies we decided to conduct in 1993, in the same area, in people with similar genetic background but with a different background diet, a further study comparing the effects on BP of fatreduced diets including different amounts of linoleic acid and different relationships between MUFA and PUFA.…”

“…Diet HP was similar to the diet of a previous intervention study conducted in the same area in 1980. 24,50 The goal for diets LF and HM was to reduce the proportion of PUFA as much as possible but their proportion could not be reduced below 3 en% by using natural foods. In all three diets fatty fish species and foods high in potassium and fibre were restricted in order to reduce differences between the diets in fish-derived n-3 fatty acids and other factors known to affect BP.…”

“…20 In the prospective Nurses' Health Study, dietary fatty acids showed no association with the 4-year incidence of hypertension. 21 An increase in linoleic acid intake has been shown to reduce BP both in combination with reduced fat intake [22][23][24][25] and with unchanged fat intake. [26][27][28][29] In contrast to these findings, several studies have failed to show an effect on BP by increased intake of linoleic acid.…”