From Ergo Log
Athletes who take a portion of cocoa two hours before training or a competition reduce the impact of their exertions on their heart and blood vessels. That’s the message reading between the lines of a human study carried out by nutritionists at the University of South Australia, which was published in the British Journal of Nutrition. The phenols in cocoa make the blood vessels more supple and reduce the increase in blood pressure that occurs with physical exercise.
Confectioner Mars has been trying for years to boost the image of chocolate – and to do so has been working on ‘healthier’ and more expensive products containing lots of extra cocoa phenols. That’s why Mars is getting research done all over the world on the positive effects of cocoa. It’s a blessing and a curse: without Mars we would know little about the protective effect of cocoa on the heart and blood vessels, but at the same time all the positive evidence is probably giving us an exaggerated view of the importance of cocoa.
Mars also financed this study. Which doesn’t mean the results are not interesting for athletes who go to extremes, including strength athletes. Blood pressure can rise so high when doing exercises like squats, leg presses and deadlifts, that sports scientists were alarmed at first.
The researchers did an experiment with 21 overweight people in their fifties. Doctors think this group should move more, but are concerned that too intensive exercise can cause blood pressure to rise too high.
The researchers wanted to find out whether they could reduce the rise in blood pressure by giving the subjects chocolate milk containing extra polyphenols from cocoa. They got the subjects to cycle for 15 minutes at 75 percent of their VO2max. That means cycling at a speed where it’s impossible to talk at the same time. Two hours before getting on their bikes the fatties drank a 200 ml chocolate shake containing 139 mg epicatechin, 39 mg catechin and 523 mg procyanidins. [The curves joining the white circles below] On another occasion the test subjects drunk a chocolate shake containing very few polyphenols. [The curves joining the black circles]
SBP = blood pressure during heart beat, systolic pressure; MAP = average blood pressure during a complete cycle of heart muscle contraction/relaxation; DBP = blood pressure between two heart beats, diastolic pressure. The figure shows the difference between values during exercise and rest.
The increase in the MAP was 14 percent less as a result of the cocoa phenols; the increase in the DBP was 68 percent less.
The amount of phenols the researchers used is the equivalent to what is contained in 163 g dark chocolate. But that amount of chocolate also contains 28 g saturated fat – 252 kcal. The researchers used a product that had had the fats removed. That might be healthier – certainly for people who are already overweight, say the researchers.
Couldnt you achieve the same effect using fruit? Or green tea? And if you combine cocoa with fish oil, maybe then you’d need less to achieve the same effect? We’ve found no research that answers these questions. And Mars is unlikely to finance research like this either.
Br J Nutr. 2010 Jan 19:1-5. [Epub ahead of print].