Many years ago - decades in fact, when we were at the start of our real Autism journey we tried it and it didn't really seem to do much, if anything.

My child takes vitamin daily because of his eating issues and it seems to have helped keep him healthy.

Not B12, but our Neurobehavioral Pediatrician did instruct us to make B6 part of the regimen for our daughter who has ODD/OCD/ADHD (and we suspect undiagnosed HFA) and our son who has LFA and ADHD. I can't say exactly how it's helped (they're both on a cocktail of medicine) but he would have explained to us what its specific purpose was, just can't recall now.

Yes . But B-12 doesn't help her Autism Spectrum Disorder