[10,11,14,15] But zinc should not be supplemented without the guidance of a nutritionist or physician, because a balance needs to be maintained between
zinc and copper. People in the autistic spectrum tend to be low in
zinc and high in copper. But if one is not autistic, supplementing zinc without copper can create a copper deficiency, and create unintended side effects. [16,17]"
Of course there are lots of other possible contributors.