Breast milk is by far the superior milk for infants, providing ideal nutrition and protection against infection. Exclusive breast-feeding up until weaning provides the healthiest start in life. Ideally it should continue during weaning and can continue as the main milk drink for as long as the mother chooses. Formula milks are the only suitable alternative from birth and during the first year of life. Compared with breast milk, some nutrients are less well absorbed and formula milks do not contain anti-infective agents to protect against infections.

Cow's milk is not suitable as a drink before 12 months of age.

Various formula milks are available in the United Kingdom and their content must comply with statutory regulations. Types include whey- and casein-dominant formulae, modified formulae for minor digestive disorders, follow-on milks for babies over six months of age, and milks designed for toddlers.
Formulae are modified as new research becomes available and developments in recent years include nucleotides, long-chain polyunsaturated fatty acids, prebiotics and fresh thinking on protein content.

Recent guidance on the safe preparation and storage of infant milks is outlined. Specialised formulae such as those for preterm infants or those with cow's milk protein allergy or inborn errors of metabolism are not included here but will be covered in a later article.