Chapter 85 - Virgin Olive Oil and Blood Pressure in Hypertensive Elderly Subjects

Abstract

In order to study the normotensive effect of virgin olive oil (VOO) in the elderly, and the possible influence of non-oleic acid components of the oil, two different VOO of the same variety, season and geographic localization were employed. The oils presented a similar composition in minor components and very little differences in oleic and linoleic acids, resulting in significant differences in triacylglycerol (TG) molecular species composition. These oils were administered within the diet to 81 normotensive and hypertensive very old subjects (mean age 84 years) at a home for the elderly for 4 weeks each, including a 4-week washout period with sunflower oil before and in between the VOO. The results corroborated previous studies, demonstrating that VOO consumption can reduce systolic blood pressure in hypertensive subjects. However, it was interesting to note that the concentrations of total and LDL-cholesterol were reduced only after consumption of the VOO with the highest triolein content. The cholesterol reduction was related with the TG molecular species composition of very-low-density lipoproteins (VLDL). In these particles, fatty acids were selectively distributed to form TG after the consumption of either VOO. Since low-density lipoproteins (LDL) are synthesised in plasma from VLDL remnants, LDL formation and composition are, in part, determined by the TG composition of VLDL and the activity of lipoprotein lipase, the enzyme responsible for their hydrolysis. Therefore, it is concluded that the differences in TG molecular species in VOO, and not oleic acid itself, were responsible for the effects on the concentration of plasma cholesterol observed. In contrast, as both VOO studied reduced systolic and diastolic blood pressure, the effect could not be ascribed to TG. Previous studies had suggested that non-oleic acid components can also cause the normotensive effect of VOO. Therefore, these results pointed towards a key role of minor components in this regard.