No proof of this at all. For all the talk and research, nothing really convincing has come out so far. There is certainly nothing wrong with ordinary vitamin or mineral supplementation for children, especially with iron. A sunken fontanelle in a healthy child is of no concern. In South Texas, where I once practiced, the belief was held by some that not only could the baby's soft spot fall, but the cure for this malady was to promptly hold the baby upside down and massage the hard palate with the practicioner's finger.
Milk normally curdles in the strong acid of the stomach soon after it is ingested.
Sugar makes children hyper. Actually, sugar loading makes a person sleepy. Sucrose solution on a pacifier actually has a sedating effect on newborns. Tickling the feet of babies causes them to stutter later in life. That was a reader submission I had never before heard.