There were 16 participants who were hypertensive women aged 56.2 +/- 5.4 years. The participants ate a diet enriched with HOSO or
olive oil for two 4-week periods with a 4-week washout period before starting the second type of MUFA diet. At entry and during study of each diet, plasma
lipids and
apolipoproteins were measured by conventional enzymatic methods. Erythrocyte membrane
lipid and
fatty acid compositions were analysed by means of the latroscan thin-layer chromatography/flame ionization detection technique and by gas chromatography, respectively. Blood pressure was also measured. The statistical analysis was conducted by using Student's two-tailed paired t-test.
RESULTS: In both groups of hypertensive patients, there was a significant increase in plasma
high-density lipoprotein (
HDL) cholesterol concentration after the HOSO or
olive oil diets, with regard to baseline. Additionally, a significant decrease in plasma
HDL2 cholesterol concentration and an increase in plasma
HDL3 cholesterol concentration were evident. The membrane free-
cholesterol concentration increased significantly and the
phospholipid concentration decreased significantly in erythrocytes after the
olive oil diet, though both MUFA diets produced a significant decrease in the concentration of membrane esterified
cholesterol. Therefore, the molar ratio of
cholesterol to
phospholipids was raised significantly in the erythrocyte membrane of hypertensive women after the dietary
olive oil, but not after the HOSO diet. In the hypertensive and normo-cholesterolaemic group the HOSO diet significantly increased the content in the erythrocyte membrane of oleic, eicosenoic, arachidonic and docosapentaenoic
acids, whereas the
olive oil diet increased the content of
palmitoleic acid and long-chain
polyunsaturated fatty acids of the n-3 family besides, compared with baseline. A significant decrease in
linoleic acid was also evident. In the hypertensive and hypercholesterolaemic group, the HOSO diet resulted in significant increases in palmitoleic, oleic, eicosenoic and behenic
acids, whereas the
olive oil diet enhanced the content of arachidonic, docosapentaenoic and
docosahexaenoic acids besides, with respect to baseline. In addition, there was a significant decrease in
stearic acid, but only after dietary
olive oil was there a decrease in
linoleic acid. The most important differences between the two MUFA diets were the increase in
n-3 fatty acids and the decrease in the n-6;
n-3 fatty acids ratio after dietary
olive oil in the erythrocyte membranes of hypertensive patients. Interestingly, a significant reduction in systolic and diastolic blood pressures was only evident after the ingestion of
olive oil.
CONCLUSION: