Chocolate lowers blood pressure 

 It’s packed with compounds called flavanols — compounds like epicatechin, catechin and procyanidins, which are extracted from cacao beans and are thought to be responsible for the formation of nitric acid in the body. Nitric acid, in turn, serves to relax blood vessel walls and lower pressure. 
100% Cocoa powder would be better than chocolate bars because it is minimally processed and contains no sugar or additives. . When choosing chocolate go  for 70% and above.