Dr Emma Ross led the experiments that showed Willie's chocolate had a positive effect for energising exercisers. Charlie Cottrell put the scientist to the test to find out what makes cacao so special
I don't eat chocolate all the time, but I do enjoy dark chocolate. I'm also keen on hot chocolate as a winter warmer.
I am an accredited sport and exercise physiologist with the British Association of Sport and Exercise Sciences (BASES). An exercise physiologist is someone who looks at how the human body responds to exercise, and we also look at how different interventions might alter the body's response to exercise. In this case, Willie wanted to test his claims that his chocolate enhances physical performance in some way.
It wasn't surprising to me that Willie has claimed some health and performance benefits from his chocolate. Chocolate is derived from the cacoa bean, one of the most concentrated sources of flavanol, a subgroup of the natural antioxidant plant compounds called flavanoids (also found in tea, red wine and tomatoes). Being a natural source of antioxidants, dark chocolate has the potential to exert antioxidant protection against free radicals, and it can contribute to improved cardiovascular health, including lowering blood pressure and improving blood flow.
Dark chocolate is also an optimal natural source of theobromine. This is the interesting component for the improved exercise performance claims, since theobromine belongs to a class of molecules called methylxanthines. Caffeine is also a naturally occurring methylxanthine, and theobromine has been shown to affect humans similarly to caffeine, albeit on a 'smaller' scale. Caffeine has been well researched in exercise science literature, and findings have shown that it can improve exercise performance, off-set fatigue during exercise, increase fat utilisation during exercise, improve neuromuscular performance and increase arousal.
If someone claims that something can positively affect exercise performance the best way to fairly test whether this is true is to conduct a randomised, blinded, placebo-controlled study. This means that the participants in the experiment perform a bout of exercise with and without the chocolate to see if they perform better by taking it, but we don't tell the participants if they are drinking Willie's chocolate or not. In the trial without Willie's chocolate we give them a similar chocolate flavoured drink (but without the high cacao content, and no real nutritional value).
Since caffeine is usually ingested about 60 minutes before exercise, we had the participants drink the chocolate drink one hour before their exercise test. Six participants completed both the trials. This means that whilst the results are a good indication of the effects of Willie's chocolate, they cannot be classed as definitive until further experiments have been conducted.
The long term effects of cacao include lowering blood pressure and generally improving cardiovascular health, improving insulin sensitivity (important in preventing diabetes), and acting as an antioxidant. Some of the short term effects of cacao have been noted as bronchodilation and its role as an antitussive (cough suppressant).
During the testing, we measured a number of physiological parameters, which give us an overall picture of the body's response to exercise. These included;
- heart rate (which gives us an idea about how the cardiovascular system responds to the exercise)
- oxygen uptake (the amount of oxygen required to perform the exercise)
- the amount of air breathed per minute (giving us some indication of respiratory function during exercise)
- the respiratory exchange ratio (a good indication of which fuel source we are using to get our energy for the exercise, i.e. fat or carbohydrate)
- perceived exertion, (the person's rating of how hard the exercise feels)
During the exercise trial where the pre-exercise drink was Willie' chocolate participants demonstrated two main differences in their performance. The first was that the ratings of perceived exertion were lower at all exercise intensities. This means that the participants felt the exercise was easier after they had drunk Willie's chocolate, even though they were exercising at the same intensities in both trials. This is an important finding because, when people find exercise feels easier they are more likely to continue exercising for longer periods of time (which has obvious health benefits). It also means that they tend to exercise at a higher exercise intensity for the same feelings of effort. This has implications for the more serious sports performer, who benefits from, for example, being able to run at a faster pace for the same feelings of effort as running at slower speeds without the chocolate drink.
The second finding was that there was a tendency for participants to utilise fat as their main fuel source after drinking Willie's chocolate. Similar findings have been observed in some trials looking at the effect of caffeine. Utilising fats for energy has benefit during exercise for several reasons. The main ones being that we have a plentiful supply of fat (unlike our limited supply of carbohydrates), so we won't run out of energy as quickly; and also, if someone is exercising in order to maintain or achieve a healthy body composition, then utilising more fat during exercise will help achieve this.
These health benefits relate almost exclusively to dark chocolate, since it is high in cacao. The lighter colour, sweeter tasting, milk chocolate is often prepared in products that dilute the cacao concentration with other ingredients that minimise the previously mentioned benefits of cacao, and also add saturated fat and calories. In addition, research has shown that milk may interfere with the absorption of antioxidants from chocolate.
Basically, the more processed the chocolate, the more of the health benefits are lost. In contrast, the reason why Willie's chocolate drink may offer health and performance benefits afforded by high concentrations of cacao (and therefore flavanoids and theobromine) is because it is pure chocolate, with nothing added, and so retains the natural qualities of these beneficial compounds.
I wasn't surprised that the chocolate drink had an effect on performance, but I was interested to see which measures it affected, and the encouraging results have also prompted me to continue investigating the effects of cacao on physical performance, since it is an under-researched topic in the exercise science literature.
Willie was quite nervous during the test - I can see that he truly believes in the power of his product. However, he rightly knows that anecdotal evidence is not enough of a claim in itself, and I admire him for putting his chocolate to the test in such a public way. There was every chance that the results might not have shown an effect. Aside from the nerves during the test, Willie was over the moon with the results that we found - albeit from a small experiment. It confirmed what he had previously believed about his chocolate drink, and provides the foundation for future investigation.
There is still a great deal of research which needs to be done before we can start claiming that Willie's chocolate drink is the 'ultimate energy drink'! Not only do we need to perform larger studies to confirm our preliminary findings, we need to investigate things like the optimal dose required for performance benefits. However, the initial findings are positive, and I believe that there is the potential for Willie's chocolate (because of its pure nature and high cacao content) to be the subject of future investigation as to how it can be used to enhance performance, either as a drink, or a bar.
The optimal serving of dark chocolate to reap both the long term benefits and short term effects is, as yet, unknown.
Dark chocolate that is unprocessed and still has a high cacao content has proven health benefits and our research has shown it may have even more potential to be beneficial in physical activity performance. However, like with anything, it is only good for us in moderation. To use another example, there is plenty of evidence that carbohydrate drinks (like Lucozade) help us perform better during exercise, but if you drink them all the time, you will be tipping the calorie scales in the wrong direction and taking in more than you are expending.
Until I met Willie I had not tasted his chocolate, but since doing the show I do use it quite a lot. This is for a few reasons; mainly because I like how unprocessed it is, so it retains all of its natural goodness and obviously it tastes good too! Since I became more aware of the benefits of the flavanoids and theobromine in the cacao, as well as the interesting findings that came out of our experiment, there's no excuse not to use it.
Peruse delicious chocolate recipes on 4Food
Catch up with Channel 4's chocolate guru, Willie Harcourt-Cooze
Watch Willie do his stuff again, free, with Channel 4 Catch-up
Mmmm - it's so good! Eat it straight off the block, or throw it in some of these chocolatey recipes
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