Not all bodies are able to cope with dairy produce. This intolerance is more common in non-western countries. Milk contains milk sugar (lactose) and some people lack the enzyme (lactase) that can convert lactose. Consequently, drinking milk may give them a sore stomach or diarrhoea.
Fermented dairy products, such as yoghurt, cheese and butter contain less or no lactose and therefore cause fewer problems. Even so, some people cannot tolerate these products either.
Others are oversensitive to milk protein. This is also known as cow’s milk allergy. People who suffer from this are allergic to the protein that is found in milk. It may give them a sore stomach or cause a rash. Products such as yoghurt and quark can also provoke an allergic reaction because they still contain milk proteins.
Read more about the nutritional value of milk