My daughter is three and one-half months old and I'm considering starting her on formula. Is there a particular type of formula that's best? Soy? Lactose free? Does it matter?
The vast majority of infants are fed one of the cow's-milk based formulas and do very well. Examples of these are Enfamil and Similac. The proteins in these formulas are milk proteins, casein, and whey.
For the small number of infants who demonstrate an allergy or intolerance to these proteins, the soy formulas substitute a soybean protein for those from milk. This situation is not as common as many feel and should be diagnosed by a medical professional.
The lactose-free option is specifically designed for infants who can't digest the sugar component of formulas. True lactose intolerance, as is found in many adults, is rare in infancy. A severe bout of diarrhea, however, can temporarily cause lactose intolerance by damaging the lining of the gut. In this case, lactose-free formulas are used for a few weeks as the intestine heals.
As a starter formula, unless there is a strong family history of milk allergy, a standard milk-based formula is the way to go. Although there are several to choose from, they are all nutritionally equivalent.