Can dark chocolate protect against stress? The effects of a single serving of dark chocolate on psychobiological stress reactivity in humans

Project leader: Petra Wirtz

Project duration: 2009 - 2015
Funding: Swiss Foundation of the Cocoa and Chocolate Industry (2009 to PW), Swiss National Science Foundation (PP00P1-128565/1, to PW)

A growing body of research suggests beneficial effects of flavanol-rich dark chocolate consumption on biological risk factors for cardiovascular disease (CHD). Psychosocial stress is a further CHD risk factor that seems to exert parts of its CHD risk by eliciting increases in biological CHD risk factors such as inflammatory and coagulation activity as well as lipid levels. To date, it has not yet been investigated whether flavanol-rich dark chocolate consumption protects from psychobiological stress reactivity such as stress-induced increases in CHD risk factors.
The project investigated the effect of acute consumption of dark chocolate on psychosocial stress reactivity. Apparently healthy medication-free non-smoking men were randomly assigned to consume either dark chocolate with flavanols or dark chocolate without flavanols. All participants underwent a psychosocial stress task two hours after chocolate consumption. Blood and saliva samples were be obtained several times before chocolate consumption as well as before and up to 2 hours after stress cessation. In addition to stress hormones, we did measure intermediate biological CHD risk factors such as coagulation activity and inflammation. Notably, in addition to assessing peripheral inflammatory measures we also measured intracellular immune activation. A thorough assessment of psychological factors completed evaluation of psychobiological stress reactivity.
This project investigated for the first time in humans whether acute consumption of flavanol-rich chocolate protects from potentially harmful effects of acute stress via a buffering effect on psychobiological stress reactivity.


Wirtz, P.H., von Kanel, R., Meister, R.E., Arpagaus, A., Treichler, S., Kuebler, U., Huber, S., Ehlert, U. (2014). Dark chocolate intake buffers stress reactivity in humans. J Am Coll Cardiol 63(21): 2297-99. [Link]

von Kanel, R., Meister R., Stutz, M., Kummer, P., Arpagaus, A., Huber, S., Ehlert, U. & Wirtz, P.H. (2014). Effects of dark chocolate consumption on the prothrombotic response to acute psychosocial stress in healthy men. Thromb Haemost 112(6):1151-8. [Link]

Kuebler, U., Arpagaus, A., Meister, R.E., von Känel, R., Huber, S., Ehlert, U. & Wirtz, P.H. (2016). Dark chocolate attenuates intracellular pro-inflammatory reactivity to acute psychosocial stress in men: A randomized controlled study. Brain Behav Immun, epub ahead of print. [Link]