- Carbohydrate intolerance especially lactose intolerance.
- Protein intolerance especially cow’s milk protein intolerance.
Both lactose intolerance and cow’s milk protein intolerance usually cause persistent diarrhoea following earlier damage to the bowel caused by gastroenteritis.
Diarrhoea due to carbohydrate induced intolerance may be caused by the excessive intake of fruit juice especially apple juice (fructose intolerance).