The Metabolic Syndrome and the Membrane Content of Polyunsaturated Fatty Acids in Hypertensive Patients

Background: Polyunsaturated fatty acids (PUFA) have been reported to be beneficial on some components of the metabolic syndrome (MetS). We tested the hypothesis that in hypertensive patients, presence of MetS and its related components is associated with cell membrane content of PUFA, a measure that reflects the dietary intake of these fatty acids. Methods: In 55 consecutive patients with primary hypertension referred to our university center, we measured anthropometric variables, 24-hour ambulatory blood pressure, general biochemistries including plasma lipids, and the fatty acid composition of red blood cell (RBC) membrane by gas chromatography. Results: The prevalence of the MetS was 36.4% and in hypertensive patients with MetS, the RBC membrane content of total PUFA, PUFA of the n-6 family (n-6 PUFA), PUFA of the n-3 family (n-3 PUFA), polyunsaturated to saturated fatty acid ratio (PUFA/SFA), and omega-3 index was significantly lower than in patients without MetS. RBC membrane total PUFA, n-6 PUFA, n-3 PUFA, PUFA/SFA ratio, and omega-3 index were significantly and directly correlated with high-desity lipoprotein (HDL) cholesterol levels, a correlation that did not differ across tertiles of plasma apolipoprotein-A1. In multivariate linear regression analysis, HDL-cholesterol resulted to be directly and independently related to RBC membrane n-6 PUFA, PUFA/SFA ratio, and omega-3 index. Conversely, total cholesterol to HDL-cholesterol ratio had inverse and independent relationship with n-6 PUFA, PUFA/SFA ratio, and omega-3 index. Conclusions: In patients with hypertension the MetS is associated with lower cell membrane content of PUFA that is explained by a direct and independent relationship of membrane PUFA with HDL-cholesterol. This observation suggests reduced dietary intake of PUFA in these patients that might contribute to their cardiovascular risk.