Impact of a Plant‐Based Diet on Central Blood Pressure and Cerebrovascular Reactivity in African Americans
Authors: Martin Zachary Thomas , Olvera Guillermo , Villegas Christian Alejandro , Campbell Jeremiah Cedric , Akins John David , Brothers R. Matthew 
Published: April 2020

African American individuals (AA) face higher mortality rates from cerebrovascular diseases than Americans from other racial/ethnic backgrounds. The cause of this health disparity is multifactorial and includes biological factors, diet, and numerous socioeconomic factors. Diets rich in whole plant foods and low in animal products may protect blood vessels through their high antioxidant capacity and low inflammatory load. Thus, we tested the hypothesis that AA adhering to a 100% plant‐based (vegan) diet (PBD) would have a more favorable dietary intake of several key nutrients and more optimal blood cholesterol, which would contribute to better blood pressure and cerebrovascular reactivity (CVR) relative to AA following a typical American diet (TAD).

METHODS

Seventeen AA participated in the study. Of them, 8 (5 female; age: 25 ± 2 years; BMI: 23.4 ± 1.4 kg/m2) were following a PBD for 2.5 ± 0.3 years and 9 (5 female; age: 21 ± 1 years; BMI: 25.3 ± 2.1 kg/m2) were following a TAD. A fasting venous blood draw was performed to assess blood lipids. Participants completed a comprehensive diet questionnaire (DHQIII, NIH). Peripheral and central blood pressures were measured via the SphygmoCor system (AtCor Medical). A hypercapnic CVR test was performed by obtaining simultaneous middle cerebral artery blood velocity (MCAv, transcranial Doppler) and beat‐to‐beat blood pressure (photoplethysmography) data at baseline and during rebreathing‐induced hypercapnia.

RESULTS

PBD AA consumed more dark green vegetables and whole grains and less cholesterol than TAD AA (p < .05 for all). Consumption of sodium, potassium, and vitamins C & E was not different between groups (p > .05 for all). Total (TC) and low‐density lipoprotein (LDL‐C) blood cholesterol concentrations were lower in PBD AA relative to TAD AA (TC: 136 ± 9 vs. 174 ± 12 mg/dl; LDL‐C: 77 ± 6 vs. 106 ± 11 mg/dl; respectively; p < .05 for both). Resting brachial (b) and central (c) mean arterial blood pressures (MAP) were lower in PBD AA relative to TAD AA (bMAP: 85 ± 2 vs. 91 ± 2 mmHg; cMAP: 80 ± 2 vs. 87 ± 2 mmHg; respectively; p < .05 for both). There were no differences between groups in the % change in MCAv nor cerebrovascular conductance (CVC = MCAv / MAP) during the progressive hypercapnic stimulus (p = .08 and p = .40, respectively). At a PETCO2 of +3, 6, 9, & 12 mmHg from baseline, MCAv increased 10 ± 4, 21 ± 3, 38 ± 2, & 43 ± 2% in PBD AA and 7 ± 2, 19 ± 3, 31 ± 3, & 39 ± 4% in TAD AA, while CVC increased 12 ± 4, 18 ± 4, 31 ± 3, & 36 ± 3% in PBD AA and 8 ± 2, 16 ± 2, 27 ± 4, & 36 ± 6% in TAD AA, respectively.

CONCLUSION

These preliminary data suggest that a diet rich in whole plant foods and devoid of animal products may be associated with healthier blood cholesterol and peripheral and central blood pressures in AA but that these differences may not yet be translating to differences in CVR.

Support or Funding Information

UTA start‐up funds to R. Matthew Brothers