There are many reasons why you might want to give someone chocolate on Valentine’s Day. There’s the tradition of it, and the idea of sweets for your sweetheart. Here’s another tempting reason: certain compounds in chocolate, called cocoa flavanols, have recently been linked with improved thinking skills. Italian researchers found people who drank a daily cocoa brew with a lot of flavanols (more than 500 milligrams) significantly improved their scores on tests that measured attention, executive function, and memory. How might cocoa flavanols boost thinking skills? They may help brain cells connect with each other. Dark chocolate is a good source of flavonols. It’s also a good source of calories. Adding it to your diet without taking out other foods can lead to weight gain, which may wipe out any health gain.