Can infants be lactose intolerant?

Lactose intolerance is extremely common among adults in our culture. According to the American Academy of Pediatrics (AAP), about 70% of the world’s population has a lactase deficiency. Lactose intolerance in more common among some ethnic groups. According to the AAP, about 20% of hispanic, asian and black children younger than the age of 5 show some evidence of lactose intolerance, whereas caucasian children typically do not develop symptoms until after 4 - 5 years of age. 

What is lactose intolerance?

Lactose is a naturally-occurring sugar in all mammalian milk. Lactose intolerance is a deficiency in the enzyme (lactase) that breaks down lactose in the gut. Common symptoms are: abdominal pain, diarrhea, nausea, flatulence, and bloating after eating lactose-containing foods. 

*It’s important to note that lactose intolerance differs from a cow’s milk allergy, which is more severe and involves a reaction of the immune system. Lactose intolerance does not cause vomiting or eczema, and these symptoms may indicate a more serious condition.

When feeding infants it’s common for them to be fussy, spit up, and have occasional wet poops. Sometimes it’s difficult to tell if these are normal activities, or if baby is having a reaction to something they ate. Since milk is the primary component of a baby’s diet, it’s easy to assume lactose intolerance may be the cause. 

In actuality, mother nature is quite resourceful, and as lactose is the primary sugar in breast milk and often the sole source of nutrition for the first 6 months, she is pretty good at making sure infants are able to digest that sugar properly. For this reason it is extremely rare for infants to be lactose intolerant, and is uncommon before the ages of 2-3 in all populations for healthy, term infants. However, it is sometimes seen more often in pre-term infants.

Best food? Mom's milk

Although it’s very rare for infants to have an intolerance to lactose, it’s not impossible. Nevertheless, because lactose intolerance will not harm your baby (as long as s/he is growing normally) and the benefits of breast milk are unmatched by formula, the AAP recommends that breastfed infants with a lactose intolerance should be continued on human milk. 

Breast milk always contains lactose and is not influenced by mom’s diet, so there’s no need for mom to stop drinking milk while breastfeeding. For formula-fed infants, lactose-free formulas are available but have not been shown to have any clinical  advantages (growth, development, etc.).  Lactose-free formulas may reduce some symptoms for your baby, but this is not always the case. 

Should kids avoid dairy?

For older children, complete avoidance of lactose-containing foods will resolve symptoms, however, avoidance of all dairy foods is not entirely necessary and has been linked with suboptimal bone development in children. There are different severities of lactose intolerance, depending on the amount of enzyme you produce. 

Some people are able to eat yogurts and aged cheese because the lactose content isn’t quite as high in these dairy foods. As calcium is very important for bones and teeth for growing children, if dairy is completely eliminated it is important to provide a calcium supplement and/or ensure adequate calcium intake from non-dairy sources. 

Talk to your doctor or dietitian if this is the case. Other options include using an oral lactase supplement, or lactose-free milk. Soy, rice and other non-mammalian milks are available as lactose-free substitutes, but their nutritional quality is not quite equal to that of cow’s milk. 

Janine Bolton