VAT on food depends on how it is sold ..... some does attract VAT (Cooked Meats, crisps, ready prepared meals for example) and of course there's all the booze, flowers, pots n pans, paper napkins, ciggies, magazines, books, stationery, CDs, DVDs, make-up, toiletries, razor blades, clothing, tights, knickers, ..... actually quite a lot of your average supermarket basket does attract VAT and that's before you see how much they sell in the way of microwaves, TV sets, DVD players, rice cookers, electric fires, electric fans etc etc.
Asda are even worse and as for Tesco ~ half the local store is given over to non food items.