What makes kefir different from yogurt is that kefir is fermented with bacteria and yeast, while yogurt is just fermented with bacteria. Elaine's position on kefir is more reflective of the intestinal diseases than autism: she feels that there is the chance of cross-reactivity between an already-overstimulated immune system and yeast from kefir. She has
said that kefir is OK for someone whose gut is well along the road to healing.
My son with the intestinal problems and colitis has documented autoimmune activity. So, for example, I would not give him kefir. My child with ASD does not have overt intestinal problems, and he's been on SCD™ for a year, so sometimes I give him kefir. Kefir is much more sour than yogurt because the bacteria have produced acetic acid rather than lactic acid, so it's not something he's wild about anyway.