I'm curious about what causes food intolerance, that is, lactose intolerance & gluten intolerance.  Does anyone know?  There is no treatment?  You just have to live with it your whole life?

I can't keep track of it: there's allergies, intolerances and sensitivities to food. As I understand it, the first is an extreme immune reaction and can kill you or make you very sick. The rest are some combination of your genetic make-up - if you can't metabolise lactose you just can't - how your immune system has been trained from early life - when you were weaned, what foods you were exposed to, whether formula or bottle fed - bad luck - sometimes your immuse sytem just fucks up - and how your gut flora and fauna are configured - if you're not used to eating a class of foods then it may make you ill because your bacteria don't know what to do with it. Oh, and hypochondria and quackery, which discredits the whole area and makes making sense of it almost impossible.

For instance, at the moment, the advice is that babies should be weaned at 17 weeks at the earliest and that they should receive no gluten until they're six months old at least, in order to avoid triggering food allergies in the immature immune system. There's also the issue that breast milk contains all sorts of things that interact with the baby's immune system to help educate it about what is food and should be ignored. Formula fed babies don't get that, so may be at higher risk of the various syndromes above. Twenty years ago the advice was to formula feed and wean them as soon as possible ...