I have no personal recommendations, but a quick Google search found that this Naturopathic Medicine clinic in Winnipeg has 6 naturopathic physicians on staff. You could ask if any of them has experience treating ASD: http://www.thenaturedoctors.ca/index.cfm

MyZettel - he saw an Occupational Therapist for many years, and as a family we did the RDI program, which was helpful. As a young adult he tried iLS, but didn't have much patience for it, and didn't feel it was making much difference. He's done some university, and holds 2 part time jobs and has a bunch of friends and has had a few dates, so does quite well. Lately, his mood has been low, and he's motivated to try diets, etc to help with this. He sees his family doctor only occasionally. So for now, he is managing without any ongoing professional support.

About a doctor knowing how to interpret the results... who sent you to Great Plains -- a parent or a doctor?
I do not know of many pediatricians who would direct you to GPL...
On the other hand, a good developmental pediatrician should... like the ones I visited in Puerto Rico - June 2011...
There are other labs doing the same type of work... do your research?
yes, it is expensive but once you confirm your child is allergic or is contaminated with a variety of elements... you believe and you will want to find a solution... stat!!
The changes to be implemented, if needed... the most difficult thing you can do.. but the rewards and results are so wonderful...
For almost 2 yrs we've been sugar/soy/casein/lactose/dairy/egg/citrus/wheat/banana/nut FREE... my daughter regressed 2yrs ago, stopped speaking, major autism behavior... and now, she's speaking again (two languages), in a blended classroom, just began speech therapy, should begin OT soon, major improvements in behavior, sleeping wayyy better, very healthy stools (they were a mess), curious, fun, entertaining...
we have a long way to go (echolalia, potty training, transitions)... but way better than what it was...
Ask many questions? Trust your instinct. Try a variety of approaches - if something does not work, read, read, read and try something else...