Lactose Intolerance and Breast Milk

By Krista Gray, IBCLC. Last updated August 2, 2017.

Tags: ,


Does Breast Milk Have Lactose?

All mammalian milks are unique and made specific for their species.  Human milk, too, is completely unique and distinct from all other mammalian milk.  It is the only milk to have more whey than casein (which gives it the “bluish” hue) and it has the highest concentration of lactose of all mammals.   Lactose is not only the principle carbohydrate in breast milk, it is essential for proper brain growth and development.  Having high levels of lactose is critical to grow a baby’s brain!

Can a Baby Have Primary Lactose Intolerance?

Babies produce an abundance of lactase – the enzyme that digests lactose.  Lactase is a brush border intestinal enzyme that begins to be produced at 24 weeks gestation and continues in abundance until 2 ½ – 7 years of age or more.1 While it is quite common to hear of older children and adults who are “lactose intolerant” it is incredibly rare for babies of any race to have primary lactose intolerance.  Primary lactose intolerance is so rare that most medical practitioners and lactation consultants will never see it in their entire lifetime. As we age, the body can begin to have an insufficient amount of lactase (the enzyme that digests lactose) which why it is common to hear of adults and even older children who are lactose intolerant.

What is Secondary Lactase Deficiency?

Secondary lactase deficiency is a symptom caused by another problem entirely.  It is possible for a baby to experience secondary lactase deficiency after using antibiotics, gastrointestinal illness, or mismanagement of infant feeding. 2 This is what is commonly referred to as “lactose intolerance.”

What are the Symptoms of Lactose Intolerance?

  • Fussiness
  • Colic
  • Excessive Gas
  • Bright green/irritating stools3

What Can I do if my Baby is Lactose Intolerant?

Unless your baby has primary lactose intolerance, which is so rare most medical practitioners will never see it during their lifetime, symptoms can be treated and breastfeeding can (and should) continue without any interruption.  Lactose intolerance is not an allergy to breast milk and not a contraindication for breastfeeding. When a baby is experiencing symptoms of lactose intolerance and breastfeeding, breast milk is not the problem and switching to formula is not the solution.

Many babies will experience lactose intolerance when the mother struggles with milk oversupply. Always drinking the lower-in-fat, higher-in-lactose foremilk can lead to a higher-than-normal load of lactose for the baby to digest. Treating the oversupply issues should resolve the lactose intolerance symptoms in baby.

When a baby has had to take a round of antibiotics or experienced any type of gastrointestinal illness, the brush border of the the gastrointestinal tract – which manufactures lactase – can be damaged.  Since lactase is the enzyme which digests lactose, a baby can experience temporary lactose intolerance while the gastrointestinal tract is healing.  Breast milk is the easiest food for a baby’s body to digest and it also has many immunoglobulins and healing properties.  Continuing to breastfeed will bring about the speediest recovery to your baby’s system.

Show 3 footnotes

  1. Mannel, R. et al. (2013) Core Curriculum for Lactation Consultant Practice, 3rd ed. Burlington, MA: Jones & Bartlett Learning, p.359.
  2. Riordan, J. & Wambach, K. (2010) Breastfeeding and Human Lactation, 4th ed. Sudbury, MA: Jones & Bartlett Learning, p. 657.
  3. Riordan, J. & Wambach, K. (2010) Breastfeeding and Human Lactation, 4th ed. Sudbury, MA: Jones & Bartlett Learning, p. 657.