Years ago, a young patient’s mother told Emily McCourt, MD, associate professor of ophthalmology at the University of Colorado School of Medicine, that she hadn’t used a prescribed ointment to treat her baby’s chemical corneal burn but instead used her own breast milk.

“I remember thinking, ‘Well, that’s interesting because this patient looks amazing,” McCourt recalls. “Then, I thought about all my patients who said they’ve used breast milk in their baby’s eyes for blocked tear ducts and rashes. There was a real opportunity to look into what was happening and why.”

McCourt, who is the chief of pediatric ophthalmology at Children’s Hospital Colorado and the Ponzio Family Chair for Pediatric Ophthalmology, took her curiosity to Mark Petrash, Ph.D., professor emeritus of ophthalmology, who spent his career studying therapeutics for eye conditions.

Petrash used the opportunity to introduce medical students to laboratory research, which continues to find that human breast milk does seem to contain healing properties useful for treating corneal wounds, although they’re not exactly certain why yet.

Observing accelerated wound healing

A recent study published by the CU ophthalmology researchers and medical students found that human breast milk used on wounded corneas in animal models experienced increased re-epithelialization, a part of the wound healing process, compared to a saline solution and a prescription medication.

“Back in 2016, we found that human breast milk seemed to enhance the healing of the cornea, but we didn’t really have any mechanistic insight to that,” Petrash says. “This latest paper looks more deeply and ask questions like, what cellular signs do we see that breast milk may be enhancing the ability of the cornea to repair itself after this very superficial wounding of the surface of the cornea?”

The research, led by Sarah Pimple, MD, who recently graduated from the CU School of Medicine, and facilitated by Department of Ophthalmology research services principal professional Michelle Pedler, measured a marker of cell proliferation called Ki67, a protein that’s produced in cells that are actively dividing. They discovered that the wounded eyes treated with human breast milk had higher levels of Ki67, a nod of legitimacy to what McCourt saw in the clinic years prior.

Quick recovery is crucial in these kinds of eye injuries because it prevents infection that may cause further damage to the eye. “The sooner that wound can heal, the better,” Petrash says. “Human breast milk seems to stimulate that process.”

It’s unclear what ingredients in breast milk may be contributing to quick recovery, but McCourt believes it’s possible that breast milk could have similar properties as serum tears, a medication made from centrifuging a patient’s own blood to separate the serum, which is then sterilized and bottled.

The serum contains components, including proteins and growth factors, that are similar to natural tears, making it an effective treatment for some patients with severe dry eye and inflammatory eye diseases.

“I’m excited to figure out why breast milk seems to work. Could we then bottle up that maternal power and turn it into an eye drop like we do serum tears? It’s hard to say right now, but it’s worth investigating,” McCourt says.

‘Tip of the iceberg’

The researchers say the work is promising and provides a solid foundation to ask more questions of what human breast milk might be able to do for wounded corneas and why. It also adds some validity to anecdotes that have been passed down from generation to generation for thousands of years.

Ancient Egyptians called breast milk the “nectar of the gods.” Greek and Roman cultures then adopted similar practices, and stories from 18th century England claim breast milk saved lives.

The research by Petrash, McCourt, and students is the beginning of a much deeper understanding.

“What we’ve observed is the tip of the iceberg,” Petrash says. “Breast milk itself is very complicated. There are sugars, carbohydrates, lactose. There are a lot of proteins that have human growth factors and different kinds of biological properties. It would be really good to know what is it about breast milk that makes it so therapeutically promising.”

McCourt advises parents to always seek out a medical professional when a child has an eye injury, but she hopes one day there may be additional options for treatment because of their research into human breast milk.

“This research supports the idea that women have known for a very long time that breast milk has potential healing properties and may be beneficial in many ways. We’re getting closer to understanding why,” she says.