Are There Traces of Milk in Persephone's Synbiotic? Here’s What That Really Means

When it comes to feeding our little ones, every ingredient matters — especially for families navigating food sensitivities or allergies. One of the most common questions we hear from parents is:

What does “May contain traces of milk (lactose)" on your box mean?

The short answer: there are trace amounts of milk sugars, but not milk proteins. Let’s unpack that together.

Human Milk Oligosaccharides (HMOs) are a key ingredient in our synbiotic. They are unique, complex carbohydrates found naturally in breast milk. They are not fats, and they are not proteins. They’re special because babies don’t digest them — beneficial gut bacteria do. Think of HMOs as the “food” that fuels good bacteria like Bifidobacterium infantis, helping them flourish and strengthen your baby’s developing gut and immune system. They’re the reason breastfed babies naturally have microbiomes rich in beneficial microbes. Importantly one of the key building blocks in HMOs is lactose, which means that a trace amount of lactose often finds its way into the final product and it is why we have the disclaimer on our label.

What does this mean for infants with cow’s milk allergy?

Most babies with cow’s milk protein allergy react to the proteins — not the sugars — in milk. Because Persephone’s HMOs don’t contain those proteins, many families managing this allergy find the synbiotic well-tolerated. As an extra precaution we test for this allergen and display the results so families can make an informed decision. Babies with lactose intolerance (which is far less common in infancy since lactose is a primary source of calories in formula and breastmilk) might be sensitive to the small amounts of lactose that may be in the product. If these babies start supplementation, they should begin with a small amount to ensure there is no sensitivity. All this being said, if your child has confirmed dairy allergies, we recommend discussing use of the synbiotic with your pediatrician before starting.

The Bottom Line

Persephone’s product includes HMOs because of the support they provide for a child’s gut microbiome. The trace lactose present is not a sign of hidden dairy proteins, but a consequence of the structure of the HMOs. As a breakdown:

• Lactose is a sugar. It’s what some babies can’t fully digest if they’re lactose-intolerant. This may be present in the product in trace amounts.

• Cow’s milk protein (casein and whey) is what triggers immune reactions in babies with true milk protein allergy. We test for these proteins and make the results accessible to parents.

• HMOs contain neither casein nor whey — the allergenic parts of dairy — and are structurally distinct from milk proteins altogether. So, while Persephone’s synbiotic contains trace lactose, that lactose is not associated with cow’s milk protein.
  

For more information about our safety and testing, please visit https://persephone.bio/pages/safety.

*Medical Disclaimer

The information provided on this blog is for educational purposes only and is not intended as medical advice, diagnosis, or treatment. Every baby is unique, and health decisions should always be made in partnership with a qualified healthcare professional. If you have questions or concerns about your child’s health, diet, or development, please consult your pediatrician or another trusted healthcare provider before making changes.