To maintain safety standards for infant health in this country, an act of Congress governs the contents of infant formula, and the Food and Drug Administration monitors all formulas. When shopping for infant formula, you'll find several basic types.
Cow's Milk–Based Formulas
Cow's milk–based formulas account for about 80% of the formula sold today. Although cow's milk is the basis for such formulas, the milk has been changed dramatically to make it safe for infants. It is treated by heating and other methods to make the protein more digestible. More milk sugar (lactose) is added to make the concentration equal to that of breast milk, and the fat (butterfat) is removed and replaced with vegetable oils and other fats that infants can more easily digest and are better for infant growth.
Cow's milk formulas have additional iron added.
These iron-fortified formulas have dramatically reduced the rate of iron-deficiency anemia in infancy in recent decades. Some infants do not have enough natural reserves of iron, a mineral necessary for normal human growth and development, to meet their needs. For that reason, the American Academy of Pediatrics (AAP) currently recommends that iron-fortified formula be used for all infants who are not breastfed, or who are only partially breastfed, from birth to one year of age.
Additional iron is available in many baby foods, especially in meats, egg yolks, and iron-fortified cereals. Low-iron formulas should not be used since they do not provide enough iron to optimally support your baby's growth and development. Some mothers worry about the iron in infant formula causing constipation, but the amount of iron provided in infant formula does not contribute to constipation in babies. Most formulas also have docosahexaenoic acid (DHA) and arachidonic acid (ARA) added to them, which are fatty acids, believed to be important for the development of a baby's brain and eyes.
Some formulas also are fortified with probiotics, which are types of "friendly" bacteria. Others are now fortified with prebiotics, in the form of manufactured oligosaccharides, to mimic the natural human milk oligosaccharides, which are substances that promote healthy intestinal lining.
Another type of formula is hydrolyzed formulas. They often are called "predigested," meaning that their protein content has already been broken down into smaller proteins that can be digested more easily. In infants who have a high risk of developing allergies (because of family history, for example) and who have not been breastfed exclusively for four to six months, there is some evidence that skin conditions like eczema (atopic dermatitis) can be prevented or delayed by feeding them either extensively or partially hydrolyzed (hypoallergenic) formulas. Ask your pediatrician to recommend a brand of hypoallergenic formula, which can reduce the risk of allergic reactions. However, these hydrolyzed formulas tend to be costlier than regular formulas. Your pediatrician can advise you on whether your child is a candidate for hydrolyzed formulas.
The hypoallergenic formulas will help at least 90% of babies who have food allergies, which can cause symptoms such as hives, a runny nose, and intestinal problems. In these types of situations, breastfeeding is particularly desirable because—when there is a strong family history of allergies—it could help avoid some infant food allergies, especially when the child is exclusively breastfed for about six months.
Soy formulas contain a protein (soy) and carbohydrate (either glucose or sucrose) different from milk-based formulas. They are sometimes recommended for babies unable to digest lactose, the main carbohydrate in cow's milk formula, although simple lactose-free cow milk–based formula is also available. Many infants have brief periods when they cannot digest lactose, particularly following bouts of diarrhea, which can damage the digestive enzymes in the lining of the intestines. But this is usually only a temporary problem and does not require a change in your baby's diet. It is rare for babies to have a significant problem digesting and absorbing lactose (although it tends to occur in older children and adults). If your pediatrician suggests a lactose-free formula, know that it provides your baby with everything that she needs to grow and develop just as a lactose-containing formula does.
When a true milk allergy is present, causing colic, failure to thrive, and even bloody diarrhea, the allergy is to the protein in the cow's milk formula. In this case soy formulas, with soy as the protein, might seem like a good alternative. However, as many as half the infants who have milk allergy are also sensitive to soy protein, and thus they must be given a specialized formula (such as amino-based or elemental) or breast milk.
Some strict vegetarian parents choose to use soy formula because it contains no animal products. Remember that breastfeeding is the best option for vegetarian families. Also, although some parents believe that a soy formula might prevent or ease the symptoms of colic or fussiness, there is no evidence to support its effectiveness for this purpose.
The AAP believes that there are few circumstances in which soy formula should be chosen instead of cow milk–based formula in term infants. One of these situations is in infants with a rare disorder called galactosemia; children with this condition have an intolerance to galactose, one of the two sugars that make up lactose, and they cannot tolerate breast milk and must be fed a formula free of lactose. Most states include a test for galactosemia in routine newborn screening, which involves performing a blood test on all newborns after birth.
Specialized formulas are manufactured for infants with specific disorders or diseases. There are also formulas made specifically for premature babies. If your pediatrician recommends a specialized formula for your infant, follow his guidance about feeding requirements (amounts, scheduling, special preparations), since these may be quite different from regular formulas.