The supermarket aisle has become a confusing place. It used to be full of recognisable items like cheese and butter; now you find yourself bamboozled by all manner of odd alternatives such as ‘raw’ hummus, wheat-free bread and murky juices. You have to stay pretty alert to make sure you pick up a pint of proper milk, rather than a soy-based alternative or one free from lactose. Supermarkets have become shrines to ‘clean eating’, a faith that promises happiness, healthiness and energy. Food is to be worshipped — and feared.