Abstract
BACKGROUND: Although it has been reported that the intermittent fasting (IF) diet has positive effects on heart health and improvement in blood pressure, it has not been sufficiently clarified how it could have these positive effects yet. OBJECTIVE: We aimed to evaluate the effects of IF on the autonomic nervous system (ANS) and renin-angiotensin system (RAS), which are closely related to blood pressure. METHODS: Seventy-two hypertensive patients were included in the study, and the data of 58 patients were used. All the participants fasted for about 15-16 hours for 30 days. Participants were evaluated with 24-hour ambulatory blood pressure monitoring and Holter electrocardiography before and after IF; also, 5 ml venous blood samples were taken for assessment of Serum angiotensin I (Ang-I) and angiotensin II (Ang-II) levels and angiotensin-converting enzyme (ACE) activity. For data analysis, the p-value <0.05 was accepted as significant. RESULTS: Compared to pre-IF, a significant decrease was observed in the patients' blood pressures in post-IF. An increase in high-frequency (HF) power and the mean root square of the sum of squares of differences between adjacent NN intervals (RMSSD) were observed after the IF protocol (p=0.039, p=0.043). Ang-II and ACE activity were lower in patients after IF (p=0.034, p=0.004), and decreasing Ang-II levels were determined as predictive factors for improvement of the blood pressure, like the increase in HF power and RMSSD. CONCLUSION: The present findings of our study demonstrated an improvement in blood pressure and the relationship of blood pressure with positive outcomes, including HRV, ACE activity, and Ang-II levels after the IF protocol.