Extensive medical research shows that mothers' milk satisfies babies' nutritional needs far better than any manufactured infant formula. It also protects babies against many common infectious diseases and certain inflammatory diseases, and probably helps lower the risk of a child later developing diabetes, lymphoma and some types of leukemia.

These conclusions appear in a major new review of the medical literature published this month entitled "Benefits and Risks of Breastfeeding."

The article, published in the current issue of Advances in Pediatrics, surveys both risks and benefits associated with breastfeeding. Many mothers and medical professionals may not understand that a great number of protective factors unique to human milk are provided by breastfeeding and how much breastfeeding's benefits outweigh its rare but often well-publicized risks, said Dr. Armond Goldman, senior author of the paper and professor emeritus of pediatrics at the University of Texas Medical Branch at Galveston.

In the United States, this misunderstanding of benefits versus risks -- in addition to social factors such as less generous maternity leave policies and poor preventive health care for much of the population -- has helped keep the rates of initiation and continuation of breastfeeding in the U.S. lower than those in most developed countries, Goldman said.

Coincidentally, the paper appeared online just before the Washington Post reported on Aug. 31 that lobbyists for the infant formula industry had succeeded in getting the federal Department of Health and Human Services to tone down a government-sponsored "attention-grabbing advertising campaign" in 2004 designed to convince mothers that their babies faced real health risks if they did not breastfeed.

A congressional investigation is examining the allegations in the Post report, which emphasized the low rate of breastfeeding in the U.S. compared with that of other industrialized nations.

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In the Advances in Pediatrics paper, said Goldman, "we tried to clarify the benefits and risks, by putting together a definitive review of both sides of the issue." He added: "Substantially more physicians and members of the public should recognize that the overall benefits of breastfeeding are much greater and the overall risks are much less than are benefits and risks from feedings using commercial infant formulas." Goldman continued, "If you understand the potential risks, most can be identified during pregnancy or shortly after birth and can be prevented or minimized."

UTMB professor of pediatrics David K. Rassin, a co-author of the paper (with Baylor College of Medicine assistant professor of pediatrics Judy M. Hopkinson), said, "Although many of us assume that everyone knows breastfeeding is best for infants and the American Academy of Pediatrics has come out with really strong recommendations in favor of it, the prevalence of breastfeeding in the United States is only about 65 percent right now." Rassin elaborated: "Historically, we had a rapid increase from about 25 percent in the Sixties up to the area of 60 percent in the late Eighties, and it's only very gradually crept up since then."

"Within the United States, where we've got clean water and don't have a lot of the diseases associated with formula feeding in Third World countries, I think we still have this concept that there really isn't any difference between breastfeeding and formula feeding," Rassin said. "One of the points we tried to make in this article is that even in this country there are definitely some health risks associated with formula feeding -- they just tend to involve diseases that take a long time to emerge but may reflect lack of breastfeeding."

In countries where clean water is unavailable to much of the population, statistics show that breastfeeding significantly reduces infant mortality. However, in some areas, such as sub-Saharan Africa, the possibility of HIV transmission through breast milk makes the risk-benefit calculation more difficult, the paper's authors note.

"Certainly in the U.S. at the moment, it would be recommended that an HIV-infected mom not breastfeed," Rassin said. "But if you look at a poor sub-Saharan African nation and try to balance off the high risks of a child dying because of a severe gastrointestinal infection from dirty water in formula versus the potential for getting HIV infection from the mom, it's a tough call. Probably, you would tend to say breastfeeding would be better in that circumstance than not breastfeeding."

Other risks identified by the authors include an insufficient transfer of breast milk, leading to dehydration and growth failure in the infant; certain vitamin deficiencies such as Vitamin D in human milk; the possibility that allergens consumed by the mother and passed to the nursing infant could cause adverse reactions; the transmission of a serious infection during breastfeeding; the exposure of an infant to certain toxic medications that are excreted in human milk; and rare genetic defects in the infant that prevent the digestion and metabolism of the milk constituents lactose, galactose and phenylalanine.

Except for genetic disorders and some infectious diseases, the authors say, none of these risks absolutely precludes breastfeeding if preventive measures are taken. In particular, Rassin said, making sure new mothers have learned proper breastfeeding technique is critical to ensuring babies get enough breast milk to keep them hydrated and growing. "The way we manage newborns now, getting them out of the hospital in 24 or 48 hours, that's not enough time to really get a mom established on breastfeeding, and moms need the appropriate support to begin the behavior," Rassin said. "It is a natural behavior, but it's not always an easy behavior to get established -- in fact, it can be very difficult during the first couple of weeks."

Goldman also emphasized the need for better physician education on breastfeeding. "It's important that physicians and others in the health care profession understand the benefits and risks of breastfeeding, recognize problems when they occur and help mothers with them," Goldman said. "Part of the difficulty is that there is insufficient time in most medical schools and most residency training programs in pediatrics, obstetrics or family medicine to more fully educate medical trainees about this important public health issue."