Allergy to Casein in Milk
Separate and distinct from lactose intolerance is the fact that some people are allergic to the casein in cow's milk. Casein is a protein in cow's milk. Casein allergy is an adverse immune reaction to casein in milk. This is when the body's immune system sees the casein protein as a foriegn and as something to fight off.
The allergic reaction can consists of swelling of lips, mouth, tougue, and face. There can be skin reaction, nasal symptoms like sneezing, congestion, and running nose. Unlike lactose intolerance, casein allergy can potentially be dangerous when serious reaction such as anaphylaxis occur. Some people with casein allergy may need to carry a shot of epinephrine in case food with casein is accidentally eaten.
About 2% to 3% of babies will have this milk allergy. Some may outgrow this allergy when they get older. Others may not.
Note that this allergy is to formula cow's milk. Babies are not allergic to mother's breast milk, which is superior to using formula milk in many ways. Although if the breast-feeding mother is drinking cow's milk herself, these casein proteins may appear in the breast milk which the baby may have a reaction to.
Casein and Type 1 Diabetes
The exact cause of Type 1 diabetes varies from case to case. It is thought to be related to genetic predisposition, environment, and virus. Type 1 diabetes is an autoimmune condition where the body's own white blood cells attacks the insulin producing cells of the pancreas. Therefore the body is not able to produce insulin, resulting in Type 1 diabetes.
But what triggers this autoimmune attack? Some hypothesize that early exposure of babies to formula cow's milk may be a contributing factor in the development of Type 1 diabetes. The theory is that the babies autoimmune system attacks the casein in the milk and inadvertently attacks the insulin producing cells of the pancreas as well since they "look similar" biochemically to the immune system.
Problems with Milk
Casein allergy is one problem with cow's milk. Another problem is that most adults are lactose intolerant. This is not as serious of a problem as casein allergy. Lactose intolerance means that the adult no longer have the lactase enzyme that they had as a child that enable them to digest the lactose sugar in milk. This is actually a normal condition as about 75% of the world's population is lactose intolerant. [reference]
Perhaps adults are not meant to drink milk. Milk are meant for children prior to weaning. Furthermore, perhaps nature did not intend for us to drink the milk of another species. With the exception of the domesticated cat, no other specie drink milk as an adult and no other specie drink the milk of another specie.