My body has already known it. Most of the time I listen to his respond to the things I eat. With dark chocolate, he reacts with deeper thougts (the opposit would be sugar or alcohol), good balanced mood and a comfortable body feeling.
But it´s nice to get my findings confirmed ;)

btw: dark chocolate (>85% of cocoa) is known to be very bitter, for many even too bitter. But same goes with the sweet or salty taste: It´s only the habit what defines your taste. For me, dark chocolate or even cocoa itself tastes more sweet than bitter after eating a lot of that. At the beginning it is a change but if you get familiar with the taste, you will find the bitter taste delicious and your body will thank you for treating him better (f.e. you will eat less sugar or salt and demand more vegetables or salat when your taste has changed)