I must admit to finding aspects of Joanna Blythman’s investigation into the processed food industry hard to swallow. With so much cod science floating around the media at the moment on the subject of detoxes and so-called ‘clean eating’, sentences such as ‘natural ingredients in their least processed forms have an inbuilt, effortless integrity that makes them the best basis for a body- and soul-sustaining life’ ring alarm bells for me.

What exactly is a ‘natural’ ingredient? How processed is too processed? What does she mean by integrity? And, most importantly, how on earth does ‘a soul-sustaining life’ manifest itself? 

The word ‘natural’ gets bandied around a lot in these pages without much in the way of explanation. Food manufacturers are criticised for buying their onions chopped and their eggs separated, both of which seem perfectly sensible efficiencies, while I can’t help feeling it’s rather unfair to object to Marks