Cognitive ability and cardiovascular help is due to
flavonols, which is found in cocoa.

Using MRI they showed that flavonols causes dilatation of
brain vessels.

It is interesting that this effect is different from the
effect of caffeine, also found in cocoa. It increases blood flow in the gray
area of the brain for three hours.

Unfortunately, during the processing many flavonols are
usually lost. Maybe in the future flavonols will be used for treatment of
stroke and dementia, researchers hope.

Ref: Neurology Reviews, March, 2007, P.20