“Eating chocolate could improve the brain’s ability to do maths”

April 3, 2009 at 8:50 pm (Media) (, , , , , , , , , , , )

Well, according to the Daily Telegraph and a conference presentation it can. It all seems a little bit flakey to me.

Apparently, “Mental arithmetic became easier after volunteers had been given large amounts of compounds found in chocolate, called flavanols, in a hot cocoa drink.” The report is based on findings that were presented at the British Psychological Society’s annual conference in Brighton. Here’s what they did: 30 volunteers were asked to count backwards in groups of three from a random number between 800 and 999 generated by a computer. Here’s what they found: it turned out that the volunteers “could do the calculations more quickly and more accurately after they had been given the drink.” According to the report, “The findings also show that the volunteers did not get as tired doing the calculations if they had been given the cocoa drink[*], despite being asked to do them over and over for an hour.” However, “the same was not true when the group was asked to count backwards in groups of seven, which the researchers described as a more complex task”[#]

Interestingly, the authors of the paper ascribe the effects of the cocoa drink to something they call “flavanol”. Flavanols are found in fruit and vegetables as well as in cocoa. If it’s true that cocoa drinks (not chocolate, as the headline states, but cocoa drinks) improve ones ability to do maths and if it’s true that it’s the flavanols that are responsible for the stated beneficial effects of the cocoa on the human brain, then surely it would have been equally correct to state that “vegetables can help improve your maths”. [To be fair to the authors of the conference paper, they do recommend the consumption of plenty of fruit and veg.] Why headline the piece “How eating chocolate can help improve your maths”? Probably because we love to be told something that runs contrary to typical advice on diet – especially when it’s something that allows us to indulge ourselves ‘guilt-free’. [The same is true of the reporting of the health benefits of red wine, I think – try googling resveratrol and red wine for an idea of the media’s over-extrapolation of studies into a specific component of red wine that also appears in other foodstuffs.]

Of course, I can’t see the research on which the Telegraph report is based because at the moment it’s a conference presentation rather than a publicly published, peer-reviewed research paper. It occurs to me, though, that 30 is rather a small number of participants for a study of this nature. It also occurs to me that, given the flavanols were provided in the form of a cocoa drink, that there could be other ingredients in the cocoa that may have had effects on the brain. Cocoa contains methylxanthines, including a certain amount of caffeine.

In a paper on the effects of energy drinks on cognitive performance, the authors stated that “The findings suggest that most of the effects of energy drinks on cognitive performance are related mainly to the presence of caffeine” [PMID: 18470842], while in this paper [PMID: 12204388] on the effects of caffeine on human behavior, it is noted that:

[*]Caffeine increases alertness and reduces fatigue; Caffeine improves performance on vigilance tasks and simple tasks that require sustained response; [#]Effects on more complex tasks are difficult to assess and probably involve interactions between the caffeine and other variables which increase alertness; Regular caffeine usage appears to be beneficial, with higher users having better mental functioning.

Given the overlap between what the research says on the effects of caffeine on mental performance and what the authors of the conference presentation found, I’d be very interested to find what sort of control (if any) was used in the research on flavanol-rich cocoa drinks (I reiterate: not chocolate, but flavanol-rich cocoa drinks).

[*]Note that caffeine is said to increase alertness in the paper by A Smith, and in the report of the (caffeine-containing) cocoa drink with flavanol.

[#]Note that the effects of caffeine are said to be more difficult to assess with regards more complex tasks. Compare this with the report of the (caffeine-containing) cocoa drink.

Linky to the Telegraph report.


  1. Alan Henness (zeno) said,

    I’m sitting here with a large spreadsheet, trying to work out some 2D to 3D transformation stuff and the chocolate cheesecake I’m eating isn’t helping much…perhaps I need more?

  2. jdc325 said,

    Maybe it’s “the wrong kind of chocolate”. Have you checked it for cocoa content? :)

  3. Elisa said,

    I saw this today and immediately wondered who had commissioned the study… the press release is here:


    “[Professor MacDonald] emphasised that the level of cocoa flavanol used in the study is not available commercially.”

    Interesting… the links to the FSA and the UK Nutrition Society are interesting too, but reading the boilerplate I’m wondering if this was aimed at education journalists in a bid to recruit more undergraduates.

    I reckon this one is more a bit of harmless fun than a sinister confectioner’s plot. This isn’t the first time the University of Nottingham have had a bit of fun with chocolate: http://www.periodicvideos.com/videos/feature_valentines.htm

  4. Elisa said,

    Ooops… just realised I’d totally miseread that as “nottingham” and posted the wrong link… the press release is here:

    Still looks like it’s promoting the department though:


    I’m guessing it was put out as a nice easter story and there isn’t much more to it, though the department could be one to keep an eye on, judging by their published research.

  5. jdc325 said,

    Thanks Elisa. I’ve just taken a look at one of the papers [linky] the department lists and it includes David Kennedy as an author (as per the chocolate research). This one looks at the effects on cognition of “a vitamin/mineral/guaraná supplement” and finds that “The vitamin/mineral/guaraná combination resulted in improved task performance, in comparison to placebo, in terms of both increased speed and accuracy […] the increase in mental fatigue associated with extended task performance was also attenuated by the supplement.” So, they found increased speed and accuracy along with a relative decrease in mental fatigue. This is what I would have expected them to find when they gave participants guarana, which contains a significant amount of caffeine. The authors, though, don’t mention caffeine. They state that the research “provides evidence that its [guarana’s] addition to a multi-vitamin-mineral supplement can improve cognitive performance and reduce the mental fatigue associated with sustained mental effort.” I’m not sure why you would want to add guarana to multivitamins and minerals when it seems you would get similar effects on cognition by simply drinking coffee. [There seem to be lots of similar papers looking at the effects of ginseng, guarana, or similar on cognition and mood.]

  6. Maddy said,

    Chocolates with all kinds of things I believe but it’s the cocoa solids % that you ahve to watch for.

  7. LeeT said,

    I am all in favour of recycling, but this “chocolate is good for you” story keeps turning up every couple of months.

    It is true, I think, that dark chocolate with 70% cocoa solids does have some beneficial effects but it also contains a high amount of saturated fats. I have seen a few chocolate wrappers which say “take two squares a days.” I don’t know about the rest of you, but I find it difficult to stop at two squares!

    There are probably better nutritional ways to benefit your mood and brain than scoffing some chocolate.

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