Cocoa flavanols protect endothelial function during prolonged sitting in healthy older adults

Sitting time is high in older adults and has been shown to temporarily impair endothelial function and blood pressure (BP). Flavanols, plant-derived compounds, acutely enhance endothelial function and reduce BP in older adults. The aim of this study was to investigate whether acute ingestion of cocoa flavanols can improve peripheral endothelial function and BP during prolonged sitting in healthy older adults. In a randomised, double-blinded, within-subject, cross-over, placebo-controlled human study, 20 apparently healthy, older adults (age, 72.4 ± 5.0 years; 7 males, 13 females) consumed a high-flavanol (695 mg) and a low-flavanol (5.6 mg) cocoa beverage immediately before a 2-hour sitting bout. Flow-mediated dilation (FMD) of the superficial femoral (SFA; primary outcome) and brachial (BA) arteries, and BP, were assessed before and after sitting. Microvasculature haemodynamics were assessed in the gastrocnemius before, during, and after sitting. Sitting reduced both SFA FMD (Δ = -0.7%; p = 0.005) and BA FMD (Δ = -0.7%; p = 0.016) in the low-flavanol condition. The high-flavanol intervention prevented the decline in both SFA and BA FMD following sitting, with FMD measures remaining similar to pre-sitting (p > 0.3). Sitting increased both systolic (Δ = 6.1 mm Hg, p = 0.001) and diastolic BP (Δ = 2.6 mm Hg, p = 0.001), with no benefit from flavanol intake. Sitting increased muscle oxygenation resting levels (p < 0.001) and haemoglobin content (p < 0.001), and decreased muscle oxygen consumption during SFA occlusion (p < 0.001). Flavanols had no effect on the muscle microvasculature. These findings indicate that flavanol-rich foods may be efficacious nutritional strategies to counteract sitting-induced endothelial impairments during prolonged sitting in older adults, but do not alleviate sitting-induced increases in BP.