Everyone knows that aerobic exercise is good for the body, but is it always as good for brain? Furthermore, is exercise better than eating lots of chocolate for the aging brain? A recent study published in the journal Nature Neuroscience by a group of scientists from Columbia University and NYU gave a large daily dose of flavanols extracted from cocoa powder to a small number of 50 to 69 year old subjects; they reported improved memory and enhanced blood flow in a part of the brain, the hippocampus, that is responsible for memory formation. If this sounds too good to be true, it probably is.
Two things about this study are disturbing and tend to undermine my confidence in their results. First, the older people didn’t benefit at all from exercising. This finding is not only inconsistent with the broad literature on this topic but is also a surprising failure by these scientists to replicate their own previous findings. Second, the supposed health benefits of cocoa flavanols have been extensively investigated in both humans and animals and consistently found to produce no real health benefits. Both the US FDA and European Food Safety Authority have refused to approve any health claims made about these chemicals.
Chocolate is an excellent example of how difficult it is to differentiate food from drug. The cocoa powder used to produce chocolate is rich in flavanols and many other potentially psychoactive chemicals. Although the amount and types of flavanols depend on how the cocoa powder was processed and manufactured, the powder produced may contain up to 10% its weight in flavanols. Overall, chocolate is not a great source of these flavanols. While expensive dark chocolate may contain anywhere from 45-80% cocoa powder, the chocolate found in the average candy bar has only about 5-7% cocoa powder.
So how much chocolate would a person need to eat in order to achieve the results reported in this study? The subjects in this study consumed a specially prepared commercial product that contained about one gram of flavanols every day for three months. One hundred grams of cocoa powder usually contains about 100 milligrams of flavanols. These values suggest that you would need to eat about one kilogram of pure unrefined cocoa powder or about 44 pounds of chocolate candy every day! Therefore, in spite of the hype surrounding this report in the popular press, I would not recommend that anyone attempt to replicate this study at home.
Headline image credit: Compound Chocolate. Uploaded by SKopp. CC BY-SA 3.0 via Wikipedia.