Breast milk contains lactose, a sugar found in all types of milk and milk-based formula. The enzyme lactase, produced in the small intestine, digests the lactose in milk. Infants with lactose intolerance do not produce this enzyme or produce a quantity too small to effectively digest large amounts of lactose. Lactose intolerance is extremely rare in infants. Depending on the cause and prognosis of lactose intolerance, some infants may continue or resume breastfeeding. Others must switch to lactose-free formula.
Galactosemia
A rare genetic disorder called galactosemia affects 1 in 60,000 newborns, according to the Illinois Department of Public Health. Infants with this metabolic disorder lack the enzyme their body needs to use galactose, a sugar formed in the body from lactose. Galactosemic newborns have difficulty eating and develop liver and immunity problems and cataracts. Their condition becomes life-threatening if left untreated. Infants with this severe form of lactose intolerance cannot breastfeed, but must be fed lactose-free formula and adhere to a lactose-free diet for life. Other forms of congenital lactose intolerance are also rare and cause diarrhea and dehydration in untreated newborns. Likewise, these infants cannot breastfeed.
Preterm Lactose Intolerance
The fetal gut does not begin to produce lactase until 34 weeks gestation. Infants born prematurely may require lactose-free formula until their bodies begin to produce lactase. Another treatment is to supplement their breast milk or formula feedings with lactase. Preterm infants are not harmed by consuming breast milk.
Secondary Lactase Deficiency
Infants younger than 3 months or malnourished infants are at risk for developing secondary lactase deficiency. Infections that cause diarrhea, such a rotavirus or Giardia parasite, injure the gut and affect the ability of cells in the intestine to produce lactase. Infected infants lose the ability to digest lactose in breast milk. Once the infection is treated, infants can resume breastfeeding.
Gastroenteritis
Infants who become ill with a "stomach flu" sometimes develop gastroenteritis, inflammation of the stomach and intestines due to a viral infection. Infants with gastroenteritis recover in four to eight weeks, depending on age; infants younger than 3 months take longer to heal. Otherwise healthy, well-nourished infants may continue to breastfeed with gastroenteritis because some lactose absorption occurs despite the inflammation in the gut. Malnourished or extremely ill babies with gastroenteritis should avoid breastfeeding because the diarrhea they experience due to the consumption of lactose could worsen their symptoms.
References
- Australian Breastfeeding Association: Lactose Intolerance and the Breastfed Baby
- Illinois Department of Public Health: Genetics and Newborn Screening, Galactosemia
- "Pediatrics"; Lactose Intolerance in Infants, Children and Adolescents; Melvin B. Heyman; September 2006
- MedLine Plus: Viral Gastronenteritis
