These can present as problems with the movement of the gut, ie. gastro-oesophageal reflux, upper gut movement disorders and constipation. Cow’s milk protein (and soya as there is approximately a 30% cross sensitivity between these two proteins in children in the gut) allergy can account for many cases of infantile gastro-oesophageal reflux and childhood chronic constipation. There is good evidence that a trial of exclusion of cow’s milk protein and soya using special milks called hypoallergenic milks or elemental milks can help substantially in determining whether children’s problems are due to this issue or not.
Older children may indeed have symptoms similar to irritable bowel syndrome due to allergies such as those with cow’s milk protein, soya or wheat and other food stuffs. This is often precipitated by a bad viral or other gut infection which then allows sensitisation of the gut to these proteins for either a short period of time or longer.
It is important not to confuse the allergy due to cow’s milk protein with lactose intolerance, which is the sugar in dairy produce. Lactose intolerance is not an allergy and very often confusion arises between cow’s milk protein, ie dairy allergy, causing gut problems and lactose intolerance, which is not an allergy but an enzyme deficiency. Intolerances to other food stuffs can also be present such as that with fructose.