Experts Weigh In: Understanding Lactose Intolerance in the Early Years

May 15, 2021
Experts Weigh In: Understanding Lactose Intolerance in the Early Years

Lactose intolerance is a common concern among Americans of all ages and is often a reason people avoid dairy. But dairy is a major source of key nutrients for Americans and an especially important source of nutrition for growing and developing children, so it’s crucial for health care providers to properly address patients’ questions about lactose intolerance. We turned to a handful of experts to weigh in on this topic – specifically as it relates to pregnancy, lactation and the early years of life. 

Pregnancy and Lactation: Can Diet During Pregnancy Cause Food Sensitivities  

The first source of nutrition in life comes from an infant’s mother – initially in utero and subsequently from breastfeeding, when willing and able. As such, moms are often curious about how diet during pregnancy and lactation affects the health and development of their child. One question you might receive, or be wondering yourself, is if moms’ food choices (e.g., dairy) are related to outcomes of food allergies or sensitivities (e.g., dairy allergy or lactose intolerance) in their children? 

According to pediatric dietitian Kirsten Bennet, Ph.D., RDN, LD, “There is no evidence that [Mom’s] avoidance of specific food allergens will prevent food allergy in an infant, including dairy.” She adds the disclaimer that “if Mom has a cow’s milk allergy, she should avoid dairy for her own health and safety.” 

Bennet’s expertise aligns with the newly released 2020-2025 Dietary Guidelines for Americans, which also advise that “unless it’s medically indicated to avoid for her own health, women do not need to restrict their choices during pregnancy or lactation to prevent food allergy from developing in their child.” 

However, special considerations should be given to breastfed infants with known allergies. If an infant has a confirmed cow’s milk allergy or diagnosis of food protein-induced enterocolitis syndrome (FPIES) caused by cow’s milk, Bennet recommends that breastfeeding moms should temporarily avoid dairy in their diet and remove dairy from the infant’s diet until the child progresses and is able to tolerate it, usually between ages 2 and 5.   

For moms and infants without cow’s milk allergies, physician assistant Liz Newton Smith, PA-C, suggests inclusion of dairy foods in moms’ diets because “dairy products, in particular, are full of essential vitamins and minerals that are not only great for pregnant women but can also have amazing benefits for their growing babies.”  

Infancy and Childhood:  Could Lactose Intolerance Really Be Causing Your Child’s Indigestion? 

Lactose intolerance is rare in young children. If infants and young children with no known allergies are fussy or experience indigestion (such as spitting up or unhealthy bowel movements) after eating, it can be challenging to pinpoint the cause. Parents and pediatricians often suspect lactose intolerance and remove dairy from the child’s diet, even though lactose intolerance rarely occurs in infancy. While incidence of congenital lactase deficiency (lactose intolerance in infants) in the U.S. is unclear, it is known to be extremely rare everywhere. In fact, in Finland, where it is understood to be most prevalent, only 0.002% of newborns are affected.  

Another situation where infants and young children might experience lactose intolerance is through secondary lactase deficiency. Secondary lactase deficiency is a result of damage to the lining of the small intestine, leading to decreased ability to produce lactase. Secondary lactase deficiency can be the result of surgery, infections, viruses (e.g., rotavirus or giardia) or diseases (e.g., celiac or Crohn’s). Lactose intolerance secondary to an underlying condition such as these is temporary and will resolve when the primary condition is treated.  

Persisting lactose intolerance in young children is therefore unlikely and parents should consult with a registered dietitian and have their child tested for lactose intolerance before removing key nutrient-rich foods, such as milk and dairy, from their diets.  

Denise Hernandez, M.S., RDN, LD, a Houston-based dietitian, stresses this point and articulates that “dairy products provide the most accessible, cost-effective and well-balanced method to ensure adequate calcium and phosphorus for the child's developing skeleton and teeth. Unnecessarily restricting or removing dairy products from the diet means that a child's family must rely on other fortified food products, beverages or supplements to meet a child's high needs after weaning from breast milk or formula.” 

Tips for Keeping Dairy in the Diet With Lactose Intolerance 

Hernandez encourages parents of children with lactose intolerance to keep dairy in their diet to balance their nutrient needs, providing these tips: 

  • Start with smaller servings of dairy to reduce risk of gastrointestinal problems 
  • Drink milk at mealtimes – consuming dairy with other foods will help slow digestion and lessen symptoms 
  • Experiment with different dairy products, as they contain differing amounts of lactose 
  • Choose lactose-reduced or lactose-free milk and milk products to get the same nutrients without the lactose 

Learn more about the recommended daily servings of dairy for Americans of all ages, including those with lactose intolerance, at or learn more about differentiating between a milk allergy and lactose intolerance