The role of milk in early nutrition is unique. For the first few months of life, it is the baby's only food. Even when solid foods are introduced into the diet, milk remains a very important source of nutrients into the second and third years of life and beyond. At no other stage of the life cycle are humans so reliant on a single food.

What is meant by ‘milk'? In this context, the term ‘milk' refers to breastmilk and infant formula in young babies (0-6 months). In older infants (>6 months old) and children, the term is also used to describe cow's milk.

As stated, in the first few months of life milk is the only food. The first few months of life are a crucial period for growth and development. Milk allergy or milk intolerance in this period effectively means that the baby's only food is making him/her unwell. This can obviously have serious implications for growth and development. A milk substitute (e.g. a hypoallergenic formula) therefore has two roles – firstly, the avoidance of allergic symptoms and, secondly, the provision of a complete source of nutrition

From around 4-6 months onwards, the non-allergic baby will start having solid foods introduced to his/her diet. Milk allergic babies should probably wait until six months of age before introducing any solid foods. As more and more solid foods are introduced, the non-allergic baby's reliance on milk will decrease and he/she will begin to consume less milk. However, this is a gradual process and the volume of milk given should not be decreased, suddenly.
For the milk allergic child, solid foods may be introduced slowly. This cautious approach is often used to help spot any new food allergies that may arise. For this reason, the hypoallergenic formula remains a very important source of nutrition in this period.
The doctor or dietitian may recommend a minimum amount of hypoallergenic formula that needs to be consumed every day.
Babies should not be given less hypoallergenic formula than the minimum recommended amount. It may be possible, however, to add some of the hypoallergenic formula to solid foods – a doctor or dietitian can advise on this.

From the age of around one year onwards, children should be taking a mixed solid food diet that is similar to the diet taken by the rest of the family. Despite this, milk remains a very important food in the diet of non-allergic children, as illustrated by the table below:

In the milk allergic child, the hypoallergenic formula may be even more important as the child will need to avoid all dairy products and foods derived from them, possibly some non-dairy alternatives too, and perhaps even some other foods also. As such, the doctor or dietitian may recommend a minimum intake of hypoallergenic formula. Children should not be given less hypoallergenic formula than the minimum recommended amount. As before, however, it may be possible to give some of the hypoallergenic formula mixed in with solid foods.