It's not surprising that some parents wonder if lactose intolerance in babies causes colic, or persistent crying. After all, lactose intolerance in adults is quite common...why wouldn't it aggravate infants?

Think about it: If it did, there would be no "witching hour." Lactose consumption is pretty steady throughout the day, but colicky fussing tends to peak in the evening. But let me explain how this theory got started, and why it's a myth.

The lactose your baby eats is digested by the enzyme lactase in the intestine. With age, adults have less and less lactase. This makes some of us lactose intolerant causing bloating, bellyache and diarrhea after eating dairy products. This adult problem led some doctors to speculate that colicky babies might be suffering from stomach pain from lactose intolerance.

Soon, the markets were flooded with lactose-free formulas (soy, lactose-free cow’s milk, and special hypoallergenic milk) and special lactase-containing colic drops…all claiming to be a cure for colic. But this multimillion-dollar promotion was based on hype not health. A Canadian study showed no improvement from lactose-free formula in colicky babies. And an Australian study found no reduction in crying when fussy infants were given lactase in their mother’s milk.

Lactose Isn't the Enemy...In fact, It's Good for Babies

Lactose literally means “milk sugar." It is made in the breast by linking together two other sugars (glucose and galactose). Lactose is so abundant in the mama’s milk that it makes the milk sticky!

Unlike regular table sugar (sucrose) or high-fructose corn syrup, lactose is very good for infants because it improves health three different ways:

  • It’s digested into glucose, the key fuel for your baby’s body…and brain.
  • It provides loads of galactose, essential for building your baby’s nervous system.
  • Any excess lactose that passes through the intestine undigested gets fermented—to gas plus a vinegar like acid—in the lower intestine. This causes frothy, acidic stools that can irritate your baby’s skin (not so nice). But the mild acid can also save your baby’s life by killing bad bacteria and boosting Lactobacillus acidophilus (fantastic!).

About Dr. Harvey Karp

Dr. Harvey Karp, one of America’s most trusted pediatricians, is the founder of Happiest Baby and the inventor of the groundbreaking SNOO Smart Sleeper. After years of treating patients in Los Angeles, Dr. Karp vaulted to global prominence with the release of the bestselling Happiest Baby on the Block and Happiest Toddler on the Block. His celebrated books and videos have since become standard pediatric practice, translated into more than 20 languages and have helped millions of parents. Dr. Karp’s landmark methods, including the 5 S’s for soothing babies, guide parents to understand and nurture their children and relieve stressful issues, like new-parent exhaustion, infant crying, and toddler tantrums.

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.