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Abstract
Flavanols have beneficial effects on vascular health and we have recently demonstrated
that cerebral vasodilatory capacity in healthy young African Americans (AA) is improved
with acute flavanol intake relative to aged-matched Caucasian Americans (CA). However,
whether the positive benefits of acute flavanol consumption would also be present
in the cutaneous microvascular circulation of AA remains unknown. Thus, we hypothesized
that acute consumption of flavanol-rich cocoa (FC) would improve the previously reported
reduced cutaneous microvascular responses to local heating in young AA. Seven AA and
seven CA participated in this double-blind crossover study. Data were collected on
two different days, separated by a minimum of one week. Two intradermal microdialysis
membranes were inserted in the forearm and each site was randomly assigned to receive
lactated Ringer's solution or NO synthase (NOS) inhibitor. Participants were randomly
assigned to consume either a non-flavanol containing (NF) beverage or FC beverage.
Cutaneous vascular conductance (CVC) was calculated as cutaneous blood flux/mean arterial
pressure and normalized as % maximal CVC (%CVCmax). The difference in %CVCmax between
the Ringer's site and NOS inhibited site was calculated to assess NO contribution
(Δ %CVCmax). In the Ringer's site, acute consumption of FC beverage improved %CVCmax
during 39 °C heating when compared to NF beverage in AA (NF: 36 ± 6 vs. FC: 47 ± 5%CVCmax;
P < .01) while there was similar %CVCmax during 39 °C heating between beverages in
CA (NF: 55 ± 4 vs. FC: 59 ± 5%CVCmax; P = .40). During 39 °C heating, NO contribution
was significantly higher with FC beverage than NF beverage in AA (NF: 27 ± 5 vs. FC:
35 ± 4 Δ %CVCmax; P = .03) while there was similar NO contribution between beverages
in CA (NF: 42 ± 4 vs. FC: 45 ± 4 Δ %CVCmax; P = .36). This data suggests that acute
consumption of FC could be a therapeutic solution to improve an attenuated microvascular
function in young AA.