When in the depths of a YouTube rabbit hole, I find myself watching celebrity food diaries. After a day of avocadoes and green juices, the end-of-day treat is often a few squares of dark chocolate, and social media is awash with claims that the stuff can enhance the health of our heart, brain and gut microbiome. This is somewhat supported by studies that hint at some beneficial effects – but are we collectively engaging in wishful thinking, or should we all be looking at how to consume more of the…