I have a second-cousin with mild autism, a cousin with aspergers, and a nephew that possibly has autism; Needless to say, I have a great interest in this condition. I have heard of all the hypes (including the one about vaccinations) and have also heard of many treatments (such as special learning setting, which was effective for my 2nd cousin I might add...). One treatment that has really spiked my interest, however, is the Gluten-Free/Casein-Free (GFCF) diet. According to WebMD, "the gluten-free/casein-free diet is based on the theory that children with autism may have an allergy or high sensitivity to certain foods." Though little research has been done on this, many parents still give it a try in hopes it could ease symptoms.
This diet involves removing all foods containing gluten (wheat products being the most common) and casein (most dairy products). This diet is strict, hard to follow, and can lead to improper nutrition being so many foods are restricted. With these products removed from an autistic person's diet, other measures will need to be taken in order to make sure the nutrition is being gotten from elsewhere.
For more information on the GFCF diet visit: http://www.webmd.com/brain/autism/gluten-free-casein-free-diets-for-autism
Watch this video for a brief overview on a book written about the GFCF diet (appeared on the Today Show):