Objective: The effect of dietary restriction on blood pressure (BP) changes to acute sympathetic activation has not been adequately evaluated. This study was designed to evaluate the effect of the Ramadan model of intermittent dietary restriction (IDR) on BP changes to acute sympathetic activation.
Method: Seventy healthy volunteers, mean age 25±1 years, participated in the study after giving written informed consent. Ethical approval was obtained from LASUCOM Ethical and Research Grant Committee. Experiments were carried out one week before (1BF) and in the 4th week (4WF) of Ramadan. Sympathetic activation was carried out using the Cold Pressor Test (CPT) with the subjects inserting their left feet for 1 minute in ice slurry maintained at 4°C. Blood pressure was measured before and after CPT. Subjects were considered hyperreactive if CPT caused ΔBP ≥+15mmHg, systolic or diastolic and normoreactive if <15mmHg, systolic or diastolic. Differences in means were calculated and compared with the student t test using GraphPad Prism version 5.01 for Windows. Data are expressed as mean ± SEM and level of significance set at p=0.05.
Results: Pressor response to the CPT was blunted by IDR (ΔSBP 19.93±1.57% at 1BF versus 15.30±1.62% at 4WF, p = 0.006) and (ΔDBP 21.93±1.98% at 1BF versus 17.12±1.83% at 4WF, p = 0.032). Vascular reactivity was also reduced by IDR though systolic hyperreactivity was higher than diastolic hyperreactivity at 1BF (60% versus 46%) and 4WF (47% versus 36%).
Conclusion: We conclude that 4 weeks’ intermittent dietary restriction modulated blood pressure responses to acute sympathetic activation.