Hi claw3.
THe best book you can get abut this is by Marilyn Le Breton - called Diets, Intervention and Autism (or similar)
it explains everything
she ahs a website, too, I htink, but it is subscription (google AllergyInduced Autism, sorry can't remeber the web address)
Basically, the hypothesis is that lots of ASD children and adults cannot break down either/both gluten and casein (the protein found incow's milk). THe incomplete breakdown of these products leaves the person with opiate-like substnces as a by-product of the digestion.
This can be tested for using the SUnderland test. Used to be the Autism Research Unit at Sunderland, now called something else, I believe. Google Paul Shattock, and it might throw up what they arenow (sorry, no links as still on my phone here)
Anyway, the opiates obscure lots of things, and unsurprisingly, peope who have this issue tend to be "addicted" to gluten/dairy foods.
dd1 is both gluten and casein free, and has been for the last 3 years.
The result have been amazing, both physiclly and emotionally.
Physically, she now at least produces proper poos, instead of runny, nasty, toxic substances that docs often refer to as "toddler diaorrhea" (how do you spell that?!). She has less bloating (and I think associated pain, but not something that she knows to tell meabout, iyswim) and isin better health overall.
Emotionally/socially the results have been startlign ot say the least. shortly after she went gf, she started talking properly - actual meaningful interaction, rather than pure echolalia she used before.she now has anormal pain response - both inbeing able to recognise pain (before, she could hurt herself quitebadly andnot notice) and in being able to tell me about it (and more crucially, exactly where is hurting)
dd1 is less anxious as well. on gluten/dairy (sadly we still have the occasional infringement - the stuff is bunged in everywhere!) she is very stressed, permanently, and paces, hand wrings, needs constant reassurance etc.
she stims less when gf/cf too.
crucially, the diet as a whole is really no gluten, no dairy, no sweetners/colourings/flavourings and no MSG.
basically, only real food, I guess. that's where life gets hard, because so many foods have things added as extra - eg even Kelloggs crnflakes have gluten in them (via barley malt added for flavouring!)
gf/cf has been oneof the best and most important things we have done for dd1 - it means she has lost the "otherworld fog" she used ot go around in (due to the opiate highs/lows) and is aware of her surroundings, meaning she is at least ready and able to learn.
hth, and if you have any questions,do ask!