Q What is the best type of baby formula to use? There are so many brands. What should I look for in a formula? — T.H., Westminster

A Your doctor may have a preferred brand of formula that he/she recommends for newborns. So ask the doctor for suggestions, or if your baby has any special requirements.

There are three major types of infant formula. The most common is made from cow’s milk. The milk is altered to provide the same amounts of carbohydrates, proteins and fat as in breast milk, which helps the baby digest the formula. You cannot substitute regular milk, goat milk or evaporated milk for formula.

Soy-based formulas are used for babies who have protein allergies or lactose (sugar) intolerance.

Again, you cannot substitute soy milk; you need to purchase soy-based formula that has been altered.

When there is a family history of milk allergies, the doctor may recommend protein hydrolysate formula, which is easier for the baby to tolerate and digest.

Many premature infants have medical conditions that affect their nutritional needs, so they may require more specialized formulas. It’s important to work with the doctor to find the most appropriate nutrition for a premature baby.

The American Academy of Pediatrics recommends that all infant formulas be fortified with iron.

Brand and generic formulas are essentially the same. Your baby may tolerate one brand better than another.

According to Vincent Iannelli, M.D., Similac and Enfamil are made with a combination of whey and casein proteins, like breast milk. Good Start is made entirely from whey protein.

The types of fat in the formula differ as well. Similac is made without palm olein oil, while Enfamil contains it. The American Academy of Pediatrics has never taken a stand nor made any recommendation about formula feeding, except to say that breastfeeding is preferred and that if you feed your baby formula, it shouldn’t be low in iron.

Even more important than the brand of formula is how you prepare it. Powdered formula is the cheapest and can be mixed whenever needed. A concentrated liquid formula is mixed with water and stored until needed. Prepared formula is convenient, but must be used within 24 hours. It’s very important to use a measuring cup when adding water to powdered or concentrated liquid formula.

Never feed your baby formula that wasn’t mixed correctly. If the formula is too concentrated or too diluted, your baby won’t receive the appropriate nutrition. If the formula is too concentrated, it may

cause electrolyte imbalance. If too diluted, your baby is underfed and hungry.

If your baby develops diarrhea, persistent or increasingly forceful vomiting, unusual tiredness or weakness or gas, contact your doctor. Babies can become dehydrated quickly.

Send your health questions to Debbie Jackson, PhD, MN, Clemson University, 302 Sikes Hall, Clemson, SC 29634-5155 or e-mail dbj@clemson.edu