You have a wonderful question. You are right, most of the time cows milk is good for our health: it has lots of calcium and other nutrients. However, what is not known is that some children and adults are very allergic to cows milk, and too much milk can ac- tually be harmful for our health.

Before going on any further, I want to mention that there is a big difference between lactose intolerance and cows milk allergy. Lactose intolerance is not an allergy, it simply means that we donʼt have the enzyme lactase in our intestines to digest lactose, which is present in cows milk and in motherʼs breast milk. Without the lactase, normal bacteria in our intestines will ferment the lactose and cause cramps, gassiness, and sometimes diarrhea. It is uncomfortable for those with lactose intolerance to consume any significant amount of dairy product, but this is not an allergy.

When we talk about cows milk allergy, we are actually talking about allergy to the cows milk protein. This is not an uncommon condition at all. Fortunately, most of the time, this allergy is relatively mild, and many donʼt even recognize it as allergy.

The most common symptom of cows milk allergy is eczema, which is a form of skin allergy. They have rough skin especially behind the ears, in the arms, and in the legs. In young infants, the skin creases in the elbows and armpits, or behind the knees and in the ankles, can become red and raw. Sometimes, these inflamed areas can develop secondary bacterial infection. On the scalp, eczema can develop into cradle cap.

Some children who have asthma can develop cough and chest congestion when they drink cows milk. In this case, cows milk is one of the triggers of asthma. Other children with cows milk allergy can have vomiting and diarrhea.

What you described in your grandson is probably the most severe form of cows milk allergy. It is quite rare, but if it is not recognized, these children can become very sick. The allergy causes damage to the intestine mucosa, which is the thin layer of cells that is responsible for digestion and absorption of food. This allergy is usually a slow process, and these children develop symptoms gradually, over weeks and sometimes months. Much of the normal mucosa that produces enzymes to digest and absorb food is damaged. As a result, children are not able to digest not just cows milk, but other foods as well. Diarrhea and sometimes vomiting are the most obvious symptoms. Because foods are not digested or absorbed, these children suffer from malnutrition even though they are being fed properly by their parents.

Their problem unfortunately doesnʼt stop there. Because of the damage to the intestines, these children actually can lose important nutrient and blood as well. As a result, anemia follows.

There is also leaking of important proteins into the gut. These proteins include albumin and immunoglobulins. Albumin is a protein that is produced by the liver. It holds onto water and other electrolytes in our blood. When albumin is lost, water will leak out of blood vessels into body tissues, causing generalized swelling that you see in the face, the abdomen, as well as in the hands and the feet.

Losing immunoglobulins can be potentially more dangerous. Immunoglobulins are specialized proteins in our blood that helps us to fight infections. Without these immunoglobulins, they become much more susceptible to infections like pneumonia and meningitis.

As you can see, severe cows milk allergy is not a trivial medical problem. Without the proper diagnosis and treatment, these children can die from malnutrition and overwhelming infection. Fortunately, his doctor was able to recognize it and changed his milk. He should stay away from cows milk for a very long time.

One last piece of information I want to add here is the danger of drinking too much cows milk. Although cows milk is generally good, it has lots of calcium, but it has very little iron. When children drink too much milk, they are not as hungry and will eat less solid food, which has much broader variety of nutrition that the body needs. Over time, some of these children can develop iron deficiency anemia. In North America, excessive drinking of cows milk is the most common cause of iron deficiency anemia.