Infant formula: The next-best thing to breast-feeding

Although breast milk is the best food for your baby, many mothers choose not to breast-feed exclusively or not to breast-feed at all. Others start out breast-feeding but need to stop before their babies are old enough to digest regular milk. In any circumstances that preclude breast-feeding, formula-feeding is the next best choice. Here's some basic information on how to choose and use infant formula.

Three main types of baby formula:

For most full-term babies, a cow's-milk-based formula is digestible and nutritionally sound, but some babies do better on a soy-based or protein-modified (protein hydrolysate) formula. More specialized formulas are available for premature infants, as well as for babies with allergies or metabolic disorders such as phenylketonuria. The three main types of infant formula are:

•  Cow's milk formula. Most formula is made with cow's milk that has been extensively altered so that it closely resembles breast milk. The alteration makes formula easier to digest and gives it the right amount of carbohydrates and the right percentages of protein and fat.

Infants have very high energy requirements. Infant formula, like breast milk, is designed to be energy-rich — about half its calories are from fat. The fatty acids included in infant formula are similar to those found in breast milk. They help in the development of your baby's brain and nervous system as well as in meeting your baby's general energy needs.

For healthy full-term infants not receiving breast milk, formula based on cow's milk is the first choice. Remember, though, that the cow's milk you drink yourself is no substitute for infant formula. Goat's milk and evaporated milk aren't either. During the first year of life, the protein in regular milk can cross through the intestine into the circulatory system, potentially leading to allergy. When cow's milk is introduced too early, anemia can also occur.

•  Soy-based formula. Babies allergic to cow's-milk proteins may use soy-based formula. Soy-based formula is also an alternative for babies unable to tolerate lactose, a sugar naturally present in milk. Babies with lactose intolerance may develop abdominal cramps, watery diarrhea and gas if they drink more than a small amount of milk. For these babies, soy formula is the formula of choice.

If you decide to give your baby a soy product, be sure to choose a soy infant formula, not soy milk. Soy milk is not nutritionally adequate for infants.

•  Protein hydroslysate formula. For infants who come from families with a strong history of milk allergy, an alternative to standard formulas is a special cow's milk formula known as protein hydrolysate formula.

Although it's more expensive than standard infant formula, protein hydrolysate formula is less likely to cause allergic reactions because the proteins in it have been broken down in a process that mimics digestion.

Most infants can thrive on one of these formulas. Competing brands of each of the three main formula types are all quite similar, so you shouldn't need to switch unless your baby's doctor advises you to. Fussiness, crying and spitting up rarely indicate a baby's intolerance to formula and won't be eliminated by changing formulas.

A few babies develop a true allergy to formula. Look for these signs and report them promptly to your baby's doctor:

•  Diarrhea — frequent, loose bowel movements mixed with mucus

•  Persistent or increasingly forceful vomiting

•  Unusual tiredness or weakness

•  A rash, usually eczema (dry, red, scaly skin)