The effect of pre-dive ingestion of dark chocolate on endothelial function after a scuba dive

Abstract

Objective: The aim of the study was to observe the effects of dark chocolate on endothelial function after scuba diving.

Methods: Forty-two male scuba divers were divided into two groups: a control (n=21) and a chocolate group (n=21). They performed a 33-metres deep scuba-air dive for 20 minutes in a diving pool (Nemo 33, Brussels). Water temperature was 33⁰C. The chocolate group ingested 30 g of dark chocolate (86% cocoa) 90 minutes before the dive. Flow-mediated dilatation (FMD), digital photoplethysmography and nitric oxide (NO) and peroxynitrites (ONOO-) levels were measured before and after the scuba dive in both groups.

Results: A significant decrease in FMD was observed in the control group after the dive (91±7% (mean±95% confidence interval) of pre-dive values; P<0.001) while it was increased in the chocolate group (105±5% of pre-dive values; P<0.001). No difference in digital photoplethysmography was observed between before and after the dives. No variation of circulating NO level was observed in the control group whereas an increase was shown in the chocolate group (154±73% of pre-dive values; P=0.04). A significant reduction in ONOO- was observed in the control group (84±12% of pre-dive values; P=0.003) whereas no variation was shown after the dive with chocolate intake (100±28% of pre-dive values; ns).

Conclusions: Ingestion of 30 g of dark chocolate 90 minutes before scuba diving prevented post-dive endothelial dysfunction, as the antioxidants contained in dark chocolate probably scavenge free radicals.