Chocolate has taken a special place in our culture, this is also reflected in the Latin name for chocolate Theobroma cacao; food of the gods. Is there something unique about chocolate?

Chocolate contains a number of ingredients that have the potential to influence cognitive functions.These ingredients are carbohydrates, flavanol and methylxanthines (caffeine and theobromine). The effects of carbohydrates and methylxanthines have been subject to many studies and these ingredients are not exclusive for chocolate. So, is there perhaps a special role for flavanol?

Flavanol comes in high concentrations in green tea, red wine, fruits and vegetables but is particularly rich in cacao. Research on the consumption of flavanol revealed that this substance is capable of passing through the bloodbrainbarrier, especially towards areas related to specific cognitive functions. This has given rise to two theories about the neurobiological and cognitive impact of flavanol:
In the first theory flavanol triggers gene expression through a series of proteincascades resulting in long term potentiation and establishing long term memories. In addition, flavanol promotes the expression of brain-derived neurotrophic factor; this strengthens synaptic growth and increases the survival of neurons. These actions primarily occur in brain areas related to learning and memory such as the hippocampus.
In the second theory, flavanol enhances cerebral blood flow and thus provides the brain with more oxygen and glucose. This can lead to general improvement of visual and cognitive performance.

These supposed mechanisms attracted the attention of Field, Williams and Butler (2011). In their research, they have put the second theory to the test. In a crossover design participants consumed white chocolate on one occasion and dark chocolate on the second.
The consumption of dark chocolate improved contrastsensitivity: the correct reading of numbers that became progressively more similar in luminance to their background. Cognitive performance was assessed with a visual spatial working memory task, a task measuring choice reaction time and a task measuring the detection time of a movement. On all these measures a significant improvement was found.

The research conducted by Field, Williams and Butler (2011) seems to support the second theory. However in dark chocolate there are other ingredients present besides flavanol. The waiting is for follow up research on both theories to give a definitive answer to the question whether there are special effects which can be accounted for by flavanol, and if chocolate has something unique in this respect.

This blog was written as an assignment for the course Pharmacology of Cognition, part of the minor Brain and Cognition.