Gluten-free: health fad or life-saving diet?

Up to a third of American adults are now avoiding gluten, and numbers in Britain are growing rapidly: gluten-free sales are soaring. But is it really our dietary enemy - or, as Jennifer Lawrence thinks, just the 'new cool eating disorder'? If your nearest supermarket is anything like mine, you will have noticed increasing space being given over to "free from" products. Sporting images of foods that look as good as their regular counterparts, the packaging hints at health benefits; the labels pro...