New research on pigs conducted at the University of Copenhagen shows that UV–irradiated breast milk may have a better effect on preterm individuals than pasteurised breast milk, which is the type of milk used today. According to the researchers, the result paves the way for studies in babies and, in the long term, a change of practice in relation to breast milk in Denmark.

Unfortunately, the production of breast milk is often delayed after a premature birth. Therefore, the healthcare sector ensures that sensitive, premature babies can receive donor milk from other mothers. Due to the risk of transferring bacteria, the milk currently undergoes heat treatment. This process is called pasteurisation.

But now, a study in pigs conducted by Yanqi Li, assistant professor at the Faculty of Health and Medical Sciences at the University of Copenhagen, suggests that UV–irradiated donor milk is more efficient in the treatment of premature babies than traditional heat–treated milk. This is the case at least for preterm piglets, which are the objects of the study and serve as a model for premature babies. Human milk can be fed to piglets, as the same type of milk can often be used in several species.

“It’s known that UV treatment has a better ability to preserve the quality of milk proteins, but this study is the first to demonstrate a beneficial physiological effect in preterm individuals. The study is important because pigs are generally good indicators of human babies, as their anatomy and development after birth are similar. We expect to find similar results in babies. So perhaps we need to rethink how we treat milk for babies,” says Per Torp Sangild, professor at the Department of Veterinary and Animal Science, who has headed the project.

UV irradiation kills the bacteria in the milk in the same way as heat treatment, while also retaining the good qualities, which heat treatment is not capable of doing. This includes, among other things, the concentration and activity of milk enzymes, immune cells and bioactive proteins. And the positive effects in piglets’ development right after birth are directly linked to the quality of the milk.

In the study, breast milk from Kvindemælkcentralen (centre for collection of breast milk) at Hvidovre Hospital was divided into three equal portions. The first portion underwent heat treatment, the second was UV irradiated and the last one was left untreated. The three milk portions were then fed to the preterm piglets.

First, the milk properties were measured, and, as expected, the properties of UV–treated milk were much closer to the properties of untreated breast milk than the heat–treated milk. The parameters on which the measurements were performed include lactoferrin, immunoglobulin and antimicrobial factors, all of which are important for babies’ ability to resist viruses and bacteria.

The breast milk from women was then fed to preterm piglets, and measurements were performed on a number of factors in their intestines. Here, the results were clear: UV–irradiated human milk produced healthier pigs than pasteurised milk. They grew faster and developed better intestinal functions and protection against bacteria, which is often a problem in preterm individuals – both pigs and humans.

There are no planned studies in premature babies. The researchers hope that it will be possible in the near future, as they see a great potential for improving the quality of breast milk from other mothers for vulnerable newborn babies.

The study is titled, “Pasteurization Procedures for Donor Human Milk Affect Body Growth, Intestinal Structure, and Resistance against Bacterial Infections in Preterm Pigs.”