Alteration of cardiovascular autonomic functions by vegetarian diets in postmenopausal women is related to LDL cholesterol levels

This study was designed to test the hypothesis that alteration of cardiovascular autonomic functions by vegetarian diets in healthy postmenopausal women is related to lipid metabolism. A total of 70 healthy postmenopausal women not on hormone therapy participated in this study: 35 were vegetarians (mean age 55.0 years) and 35 were omnivores (mean age 55.1 years). Cardiovascular autonomic functions and baroreflex sensitivity were evaluated by specific frequency-domain measures of heart rate variability (HRV) and arterial blood pressure fluctuation. The vegetarians had statistically significant lower blood pressure, total cholesterol, low-density lipoprotein (LDL) cholesterol, triglyceride, and fasting glucose levels compared with the omnivores. The vegetarians exhibited a significant higher total power, low-frequency (LF; 0.04-0.15 Hz) and high-frequency (HF; 0.15-0.4 Hz) of HRV and increased baroreflex sensitivity measures [Brr(LF) and Brr(HF)] compared with the omnivores. Total power, LF and HF of HRV, Brr(LF), and Brr(HF) were significant negatively correlated to LDL-cholesterol concentrations (P ＜ 0.01). We conclude that the increases of cardiac vagal activity and baroreflex sensitivity by vegetarian diets in postmenopausal women are inversely related to LDL-cholesterol levels.