This article is part 1 of an overview of infant nutrition. It discusses government and European Union advice, as well as the specific nutrients contained in breast milk and breast milk substitutes. Essentially breastfeeding should be recommended to all infants for at least the first six months of life and continued for as long as the mother wishes. Breastfeeding women and breastfed infants over six months should be advised to take a vitamin D supplement. Weaning should not begin before six months, but at least not before four months. Breast milk is the ideal source of nutrition for infants because of its immunomodulatory components and its nutritional profile. If mothers choose not to breastfeed, cannot breastfeed or need to use a top-up feed, ordinary cows' milk should not be used for a number of reasons. Cows' milk based infant formula is the only suitable alternative. Midwives should be well informed regarding the benefits of breast milk and how the different formulas compare to breast milk and to each other. This will enable them to convey up-to-date information to pregnant women/mothers. Part 2 will discuss allergy prevention in small babies.