Long-term effects of four fat-modified diets on blood pressure.

The purpose of the present study was to examine the effects of four fat-modified diets on BP in 160 middle-aged subjects most of whom had mildly to moderately elevated serum total cholesterol levels and to analyse the relationship of BP to fatty acid composition of serum cholesterol esters. After screening, the subjects (74 men and 85 women) were randomised for the next six months into one of the four experimental diets: control diet (high in saturated fats) (35/14:10:4, indicating 35% of energy from total fat/14% from saturated, 10% from monoenes and 4% from polyenes in the actual diet), AHA (American Heart Association) type diet (32/10:8:8), monoene-enriched diet (34/11:11:5) and low-fat diet (30/12:8:3). Serum total cholesterol decreased significantly during the AHA type diet and monoene-enriched diet in both men and women. No significant changes were found in BP levels in any of the groups in the long-term when both sexes were analysed together but in men the AHA type diet resulted in a significant decline in SBP (-4.5 -7.9 mmHg, mean +/- SD) and a consistent reduction was also found in DBP (-2.1 +/- 8.4 mmHg). In contrast, control diet induced a significant rise (+5.5 +/- 14.3 mmHg) in both SBP and DBP (+3.4 +/- 8.4 mmHg) in men. In women, no persistent significant changes in BP levels were observed. An increase in the sum of proportions of myristic (C14:0), palmitic (C16:0) and palmitoleic acids (C16:1) of serum cholesterol esters was associated with the elevation of BP in men of the control group. Furthermore, at baseline, BP had significant positive correlations with C14:0, C16:0 and C16:1 of serum cholesterol esters in the entire study population whereas linoleic acid had an opposite effect on BP even after adjustment for body mass index and age.