Breastmilk offers the newborn protection against disease. This benefit has been recognized for hundreds of years; however, only in the last few decades have investigators begun to identify the specific anti-infective components of human milk that make it a peerless substance for feeding the human infant. Breastmilk has been viewed from ancient times as living tissue and rightly so. This "white blood" contains enzymes, immunoglobu-lins, and leukocytes in abundance. These components, one frequently enhancing the efficacy of another, account for most of the unique anti-infective properties of human milk. In some cultures, fresh breastmilk is used as eyedrops to treat conjunctivitis; elsewhere, it is common practice to apply breastmilk on the skin to heal cracked nipples. Breastmilk provides several tiers of defense against diseases of infants that include a top tier of secretory antibodies against specific pathogens, next a tier of fatty acids and lactoferrin that provide broad-spectrum protection, followed by glyco-con-jugates and oligosaccharides, each protecting against one or more specific pathogens (Newberg et al., 1998).
Studies that measured the protectiveness of human milk reaffirm its significance in preventing infections (Dewey, Heinig, & Nommsen-Rivers, 1995; Frank et al., 1982; Gulick, 1986; Kovar et al., 1984; Kramer et al., 2001; Pullan et al., 1980; Rosenberg, 1989; Victora et al., 1987). The evidence is strongest for bacterial infections, gastroenteritis, and necrotizing enterocolitis but is less convincing for respiratory infections (Kramer et al., 2001).
Wherever infant morbidity and mortality are high, breastfeeding conclusively helps to prevent infantile diarrhea and gastrointestinal infections (Almroth & Latham, 1982; Brown et al., 1989; Clavano, 1982; Duffy, 1986; Espinoza, 1997; Granthan-
McGregor & Back, 1972; Habicht, DaVanso, & Butz, 1988; Jason, Niebury, & Marks, 1984; Koop-man et al., 1985; Kovar et al., 1984; Mitra & Rabbani, 1995; Perera et al., 1999; Ravelomanana et al., 1995; Ruuska, 1992). Breastfeeding minimizes diarrhea both by providing protective factors and by reducing exposure to other foods or water that may contain enteropathogens (Van Derslice, Pop-kin, & Briscoe, 1994). As antibiotic resistance becomes a global problem, discoveries about the protective effect of breastfeeding become even more important (Hakansson et al., 2000).
Protection is dose-dependent. In a review of field studies conducted to identify the effect of breastfeeding on childhood diarrhea in Bangladesh, children partially breastfed had a greater risk of diarrhea than had those who were exclusively breastfed (Glass & Stoll, 1989). Although breastmilk's protective effect is most easily demonstrated in areas of poverty and malnutrition, evidence of this protection is worldwide. In China, Chen, Yu, and Li (1988) showed that compared with breastfed infants, artificially-fed infants are more likely to be admitted to the hospital for gastroenteritis and other conditions. In the Cebu region of the Philippines, giving water, teas, and other liquids to breastfed babies doubled or tripled the likelihood of diarrhea (Popkin et al., 1990). Young Nicaraguan children who develop rotavirus infections very early are partially protected by specific IgA antibodies in their mothers' milk. Rotavirus in stool samples correlated significantly with the concentration of anti-rotavirus IgA antibodies in colostrum (Espinoza et al., 1997). Canadian infants exclusively breastfed for the first 2 months had significantly fewer episodes of diarrhea than did infants bottle-fed from birth (Chandra, 1979). Breastfed children in Burma required less oral rehydration solution than did those who were not breastfed during the early acute phase of diarrhea and recovered from diarrhea more quickly (Khin-Maung et al., 1985).
A major methodological problem in breastfeeding research on disease is the dose response effect—i.e., the greater the amount of breastmik the infant receives, the greater the protection against disease; protection improves with the duration of breastfeeding. A lack of a clear consistent definition of breastfeeding is a flaw in many breastfeeding studies given the fact that there is a wide variation in feeding practices and that mothers often erroneously report supplements given to the infant (Aarts, Kylberg, Hornell et al., 2000; Zaman et al., 2002). Moreover, it is neither feasible nor ethical to randomly assign mother/infant dyads to breastfeeding or formula feeding groups.
Kramer et al. (2001) got around this problem by looking at infant outcomes of hospitals and clinics in Belarus that introduced Breastfeeding Friendly Hospital Initiatives and compared them with hospitals and clinics that continued their traditional practices. Results indicated that infants at the intervention site were more likely to breastfeed to any degree at 12 months and were more likely to be exclusively breastfeeding at 3 and 6 months. The risk of gastrointestinal infections and atopic eczema were significantly lower in the intervention group but there was not significant reduction in respiratory tract infection.
Epidemiological evidence indicates that human milk continues to confer protection even with supplementation. Partial breastfeeding is better than no breastfeeding at all. This protection is specific to pathogens in the mother's and infant's environment. Moreover, the infant receives protection against the pathogens it is most likely to encounter. Table 4-4 summarizes the ameliorating and protective effects of human milk. We assume that breastfeeding is the norm and that artificial feeding is a deviation from the norm that brings about hazards to infant health. Two infant health problems exacerbated by lack of breastfeeding—respiratory illness and otitis media—are discussed here. Others are discussed throughout this book, especially in Chapters 18 and 19.
Studies of the protective effects of breastfeeding against respiratory tract infections are conflicting and complex because of error in parents' reports and other conditions not related to feeding. Several studies suggest that breastfeeding helps to prevent respiratory illnesses (Abdulmoneim & Al-Gamdi, 2001; Cushing et al., 1998; Lopez-Alarcon, Villal-pando, & Fajardo, 1997) and others indicate little protection (Dewey, Heinig, & Nommsen-Rivers, 1995; Kramer et al., 2001). There is, however, strong evidence that breastmilk protects against res-
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For many years, scientists have been playing out the ingredients that make breast milk the perfect food for babies. They've discovered to day over 200 close compounds to fight infection, help the immune system mature, aid in digestion, and support brain growth - nature made properties that science simply cannot copy. The important long term benefits of breast feeding include reduced risk of asthma, allergies, obesity, and some forms of childhood cancer. The more that scientists continue to learn, the better breast milk looks.