The reasons a baby drinks soy formula vary. Some babies show signs of being lactose intolerant, while others may be on soy formula because of colic or the parents' diet preferences. The recommended age to switch a baby from formula to whole milk is 12 months according to babycenter.com, but you should always consult your doctor before making the switch. Many parents choose to make the switch to whole milk gradually and this change can be broken down into several steps.
Consult your baby's physician before beginning the switch to whole milk. Once he says it is OK to begin making the switch, do it gradually.
Mix a couple of tablespoons of whole milk with some cereal or fruit and offer it to your baby. The texture of whole milk is different from formula, so your baby may be hesitant to consume it in the beginning.
If your baby doesn't have any adverse reactions to small amounts of whole milk mixed with your baby's food, mix one part whole milk with three parts formula in a bottle or sippy cup and feed it to your baby. Watch for reactions to the cow's milk and call your doctor if you notice any changes.
If your baby doesn't have any reactions to small amounts of whole milk mixed with his formula, gradually increase the amount you are feeding him until he is drinking 16 to 24 ounces a day. According to babycenter.com, a one- to two-year-old baby should drink about 16 to 24 ounces of whole milk in a day. However, make sure your baby isn't drinking too much milk making them not hungry for other nutritious foods such as fruits and vegetables.