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

Abstract

We compared the effects on blood pressure (BP) of three isocaloric diets with reduced total fat and saturated fatty acid (SAFA) contents but with different proportions of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). Diet LF (low fat) provided 20 en% fat (7.9% SAFA, 7.8% MUFA, 3.0% PUFA); diet HP (high PUFA) 26 en% fat (7.5% SAFA, 8.2% MUFA, 8.1% PUFA), and diet HM (high MUFA) 26 en% fat (7.3% SAFA, 14.1% MUFA, 3.2% PUFA). The diets were consumed for 8 weeks (intervention) preceded by 2 weeks and followed by 8 weeks on a habitual diet (baseline/ switchback) with 33-34 en% fat (13-14% SAFA, 12% MUFA, 6% PUFA). Forty-five free-living couples were randomly allocated into the three diet groups, and 43 men and 44 women completed the study. BP was measured weekly with an automatic device. Compliance to diet was monitored by repeated food records, serum

Evidence-Based Guideline of the German Nutrition Society: Fat Intake and Prevention of Selected Nutrition-Related Diseases

“…In the same study, there was also no difference compared to a low-fat, SFA-rich diet (20 en% total fat, 8 en% MUFA, 3 en% PUFA, 8 en% SFA) [149] (LOE Ib).…”

“…In intervention studies with normotensive people, no significant relations between the intake of SFA compared to n-6 fatty acids and blood pressure could be observed [144,145,146,147,148,149]. The substitution of SFA with MUFA under isocaloric conditions had no influence on blood pressure either [27] (LOE Ib).…”

“…No significant relations between intake of n-6 fatty acids compared to SFA and blood pressure were observed in intervention studies with normotensive persons [144,145,146,147,148,149]. …”

Dietary fat composition and the metabolic syndrome

“…This association has also been found in a Norwegian population [48] and confirmed in the 8-year prospective evaluation of the Chicago Western Electric Study [49]. In intervention studies the reduction of total and saturated fats, by using low-fat dairy products and a diet rich in fruits and vegetables, lowers systolic and diastolic blood pressure; whereas an increase in polyunsaturated fatty acid intake gave inconsistent results in randomized controlled trials [50][51][52][53][54]. In a 1-year cross-over trial in hypertensive individuals, monounsaturated fat seems to reduce blood pressure better than polyunsaturated fat and reduces the need for antihypertensive medication [55].…”

Diet Modifications to Control Hypertension: The Multifactorial Approach

“…Results from epidemiological studies relating total fat intake to blood pressure have not been consistent. In diet intervention trials aimed toward reducing total fat and saturated fat intakes, a reduction in blood pressure has been observed in some but not all of these studies [15,16]. In contrast, results from a meta-analysis of 17 controlled clinical trials that examined the effect of n-3 fatty acid supplements on blood pressure found significant reductions in blood pressure in individuals with hypertension (but not in normotensives) [17].…”