No compelling evidence exists to support the assertion of causality between the vaccines (MMR and TCVs) and autism.
The dramatic increases of autism cases would be expected given the low serum d scenarios with pregnant women of color in northern continents.
Since autism has been shown to be associated with changes in the structure of the brain including in some cases a section of the brain stem that is missing entirely, it's not at all clear that providing vitamin D and feeding non-allergenic foods is going to solve the problem.
That said, I do have some friends with a daughter who had been diagnosed as autistic and who has no vocabulary at age six. They did discover that removing wheat from her diet caused a considerable improvement in her behavior. They ascribed this improvement to the fact that their daughter had previously been in pain when trying to digest what products. But their daughter still has extremely severe problems. She has subsequently been diagnosed with Angelman syndrome.
Celiac is caused by any one of 9 different genes with variant alleles.
It can, if left untreated, result in holes being torn into the walls of the small intestine. Undigested food can get into the blood stream as a consequence and cause all sorts of problems.
The treatment is total avoidance of gluten containing substances such as wheat, barley and rye.
No beer for you! And be very careful with those salad dressings and barbeque sauces made from malted barley (Jack Daniels for example).
Celiac, however, does not cause autism ~ rather, it causes misery if untreated, and less misery if treated. There's not even a good statistial relationship between the two situations, but I've heard from folks with such a child that his behavior was dramatically improved after gluten was removed from the diet.