Is my baby lactose intolerant?

🍼

Lactose: The #1 Sugar in Breast Milk (and What That Means for Your Baby)

Let’s talk about lactose—the main carbohydrate in human milk. Yep, milk has sugar. And it’s meant to.

💡What is lactose?

Lactose is a milk sugar made of two smaller sugars: glucose + galactose.

It’s the primary source of energy in breast milk—making up about 7% of its composition (or roughly 7g per 100mL). It fuels that rapid baby brain growth and gives your baby the energy they need to do all that developing and growing 👶🧠

🧬How do babies digest lactose?

Babies (and all mammals) are born with an enzyme called lactase. This enzyme lives in the small intestine and is responsible for breaking down lactose into those two smaller sugars so it can be absorbed.

No lactase = no lactose digestion. And undigested lactose? That can cause gas, bloating, and diarrhea.

🚨So, what about lactose intolerance?

Here’s where it gets interesting:

• True congenital lactose intolerance (being born without lactase) is extremely rare—we’re talking less than 1 in a million babies worldwide.
• The most common form of lactose intolerance is lactase non-persistence, when lactase levels naturally decrease after weaning, usually after age 2–5, depending on genetics.

🌍 Global stats:

• 65–70% of the world’s population has some degree of lactase non-persistence in adulthood.
• Highest rates: East Asian, West African, Native American, and some Mediterranean populations.
• Lower rates: Northern European ancestry (many retain lifelong lactase activity).

🍼BUT newborns and young infants—regardless of ethnicity—are supposed to be able to digest lactose. It’s built into the system.

😬Why do some babies 

seem

 lactose intolerant?

There are a few reasons you might see symptoms like gas, frothy poops, or fussiness:

1. Lactose overload – often from an imbalance in foremilk/hindmilk (baby’s getting a lot of high-lactose milk but not enough fat to slow digestion).
2. Gut inflammation – from illness, food allergies (like cow’s milk protein), or gut immaturity, which can temporarily reduce lactase production.
3. Misdiagnosis – some babies with colic or reflux symptoms get labeled “lactose intolerant” when it’s not the root cause.

✨So what’s the takeaway?

• Lactose is the main sugar in human milk—and that’s by design.
• Babies are born with plenty of lactase to digest it.
• True lactose intolerance in infants is incredibly rare.
• If your baby seems uncomfortable, it’s worth digging deeper—but it’s probably not about lactose.

💬 Real talk:

If you’ve been told your baby is “lactose intolerant” and to stop breastfeeding—please know that’s almost never necessary. Get a second opinion. Email me at lalactation@gmail.com to set up a consultation.