What are the main types of infant formula?

Commercial infant formulas are regulated by the Food and Drug Administration (FDA). Three major types are available:

• Cow milk protein-based formulas. Most infant formula is made with cow's milk that's been altered to resemble breast milk. This gives the formula the right balance of nutrients — and makes the formula easier to digest. Most babies do well on cow's milk formula. Some babies, however — such as those allergic to the proteins in cow's milk — need other types of infant formula.
• Soy-based formulas. Soy-based formulas can be useful if you want to exclude animal proteins from your child's diet. Soy-based infant formulas might also be an option for babies who are intolerant or allergic to cow's milk formula or to lactose, a carbohydrate naturally found in cow's milk. However, babies who are allergic to cow's milk might also be allergic to soy milk.
• Protein hydrolysate formulas. These types of formulas contain protein that's been broken down (hydrolyzed) — partially or extensively — into smaller sizes than are those in cow's milk and soy-based formulas. Protein hydrolysate formulas are meant for babies who don't tolerate cow's milk or soy-based formulas. Extensively hydrolyzed formulas are an option for babies who have a protein allergy.

In addition, specialized formulas are available for premature infants and babies who have specific medical conditions.