Chocolate bait and switch

Headline:  Study: Dark chocolate calms you down

Lead:

Eating dark chocolate can calm you down according to a new study.

Number of people actually given dark chocolate in the study: 0 

Also, from the paper behind the story

Following 30 days of treatment, there were no significant effects of cocoa polyphenols on any of the cognitive factor scores.

That is, the differences on these questionnaires between people given drinks with or without cocoa chemicals were no larger than you’d expect by chance. The closest measurement to statistical significance was “Power of attention”, where the results were  worse with more cocoa chemicals.

A different question, where participants picked a point on a line to indicate ‘Calmness’ or ‘Contentedness’, was different between the treatment groups, even though the questionnaire that was supposed to measure the same mental qualities wasn’t. So the results are, at best, mixed.

Another interesting section from the paper is

As previously reported elsewhere (Camfield et al., 2012), participants in this study also had Steady State Visually Evoked Potentials (SSVEP) measured in response to a spatial working memory task…. Although cocoa polyphenols supplementation did not affect accuracy or response time, some phase differences at posterior-parietal and frontal sites were significantly different between the treatment groups

That is, this is the second analysis to be published from this study, and the first analysis also didn’t find what was hypothesised, although it did find some differences that might be interesting.

This is exactly the sort of research that may be worth doing, but shouldn’t be in the mass media, especially mislabelled as a health benefit of dark chocolate.