Primary Care Corner with Geoffrey Modest MD: Dark Chocolate helps with peripheral arterial disease (PAD)
29 Sep, 14 | by EBM
A recent article on the impressive role of dark chocolate in improving walking for patients with PAD (see DOI: 10.1161/JAHA.114.001072). I can’t resist it: so many bad things going on around the world and here is a chance to trumpet a universal (or nearly so) positive. So, in this remarkably important study (albeit small, with only 20 patients, mean age 69, 85% with hypertension, 30% diabetes, 90% dyslipidemia, 80% former smokers, 60% on ACE-I, 100% on statins, 95% on anti-platelet drugs), they measured maximal walking distance (MWD) and maximal walking time (MWT) in those randomly given 40 g of dark chocolate (>85% cocoa) vs. 40 g of mild chocolate (<=35% cocoa) in single-blind cross-over design study, checking the MWD and MWT at baseline and 2 hours after chocolate ingestion. And…
–dark chocolate increased MWD by 11% (p<0.001) and MWT by 15% (p<0.001). MWD increased from 110.7m to 122.2m, MWT from 124.8 to 142.2 seconds. also flow-mediated dilation doubled (p=0.003)
–dark chocolate also increased serum NOx by 57% (p<0.001) and decreased serum isoprostanes by 23% (p=0.01), and sNOX2-dp by 37% (p<0.001)
–no change in above after milk chocolate
There are some data suggesting that oxidative stress as well as endothelial dysfunction, reduced glucose-oxidation, accumulation of toxic metabolites, impaired nitric oxide generation (above study measured the metabolic endproducts of serum nitrite and nitrate, or NOx) play a role in intermittent claudication. Cocoa is rich in polyphenols, which induce arterial dilation (by lowering activation of NOX2, catalytic substrate of NADPH oxidase, which acts as a vasoconstrictor — above study measured the sNOX2-dp, the serum NOX2-derived protein). This study suggests that dark chocolate down-regulates NOX2-mediated oxidative stress (perhaps mediated by the polyphenols). Other data note increased arterial dilation in smokers with dark chocolate.
Of note, these very positive changes were after only 40 g of dark chocolate. Just imagine the effects of a much higher dose? Continuous infusion? This study does not undermine the most important PAD therapies: stopping smoking and exercise; it just raises the possibility of combo therapies — eating dark chocolate instead of smoking, or eating dark chocolate while walking.