Racial Specificity In The Hypotensive Effects Of Dietary Capsaicin: A Spicy Conclusion

Cardiovascular disease (CVD) is the leading cause of death in the United States, and most pervasive among non-Hispanic Black/African Americans (AA). Central blood pressure and vascular stiffness are relatively novel independent risk factors for CVD. Whether racial disparities exist in these parameters, and the potential role of cardiac autonomic nervous system activity (estimated via heart rate variability) is unknown. Further, eating spicy peppers and its active ingredient, capsaicin, is suggested to reduce CVD deaths, with potential to reduce racial disparity in CVD. PURPOSE: To determine racial differences in central and peripheral BP and vascular stiffness between young healthy AA and Caucasian (CA), in response to capsaicin, and if HRV can explain such differences. METHODS: In a randomized crossover design, 25 young AA (n = 13 (4 female), 19 ± 1 yrs) and CA (n = 22 (10 female), 20 ± 2 yrs.) were assessed for peripheral systolic (SBP) and diastolic (DBP) BP, central systolic (cSys), diastolic (cDia) BP, augmentation index normalized to 75 beats/min (AIx@75), and pulse wave velocity (PWV) in duplicate using an automated oscillometric sphygmomanometer under capsaicin and placebo conditions. Time-domain indices of HRV, root mean square of successive differences (RMSSD), and standard deviation of n-n intervals (SDNN) were obtained via HR monitor and analyzed. RESULTS: In SBP of AA and CA, there was a significant interaction of treatment*race p = 0.03, η2p = 0.19. The same trend existed in cSys of AA and CA (treatment*race p = 0.048, η2p = 0.17). Specifically, in response to capsaicin, the AA SBP was reduced by ~5 mmHg but the CA increased 3 mmHg. The AA and CA response to capsaicin on AIx@75 approached significance in the interaction of treatment*race p = 0.08, η2p = 0.13, trending similar to BP with improvement in AA. No differences were noted in terms of HRV regarding race, treatment, or their interaction (all, p > 0.05). CONCLUSION: The blood pressure-lowering effect of acute dietary capsaicin on peripheral and central systolic blood pressures was dependent upon race, where AAs responded favourably, but CAs actually tended to increase modestly. These results do not appear to be due to differing cardiac autonomic activity response to capsaicin, suggesting other mechanisms are responsible, and warrants further study. Support: American Heart Association Grant#24AIREA1247045 (SJI)