This is not one of my specialist fields, but I can point you in the right direction.
Here are some links to great resources that should help you:
A BBC Health page on Autism and Asperger Syndrome, a good introduction
About Autism - a site written by a parent of an autistic child
Autism Research Centre - a more scientific look at the subject
FoodsMatter - research reports, causes, management and links with vaccines, food sensitivity, gluten etc
These flyers, albeit from Spectracell, a nutritional testing company, I think are an excellent aide-memoire for the nutrition connections with autism (and ADHD). Could give you a place to start. I do now offer their test actually because it is the only one where I have found intracellular vitamins and other elements like CoQ10, the key antioxidants like glutathione and E Complex, plus carbohydrate and fructose sensitivity in one test. You can read about it here; it is pricey but it is cutting edge too.
There is a fabulous article written about the work of the original pioneer for using orthomolecular medicine (ie. nutritional therapy) for behavioural issues in children on WDDTY. You do have to subscribe to read it - do a trial, maybe - but it gives hope and specific recommendations for treatment so I've included it here for you. Have a read: Magic Bullet.
Having read this page, Caring4ourkids.com contacted me to suggest some other useful articles. I particularly found these two full of practical information:
I hope that helps.
Click here for more info on what's in it ...
Then, please use the links on the site. Doing this helps us offer this free website and support to you and others. Thank you, we all appreciate it. Some people have asked for a donate button, which is lovely, so here it is. Thank you!
Please feel free to share material from this site (not paid-for items) as long as you do not alter it and give full credit plus a link back to this site. Enjoy.
The information given is not meant to be a substitute for seeing a health professional. It is our opinion only, based on several years of natural medicine practice and research. We're sure you'll find it useful, but please use it wisely and always exercise common sense.