New research from the BioDairy project shows that the milk sugar lactose plays an active role in gut health. Gut microbes convert lactose into butyric acid, which, according to the researchers, may help strengthen the balance of the immune system and counteract autoimmune and allergic reactions.

There is often debate about lactose’s journey through the digestive system, but a new research project – BioDairy – carried out in collaboration between Aarhus University and the University of Copenhagen highlights lactose’s positive properties for the microbiome.

Using specialised model systems and stool samples, the researchers examined how gut bacteria respond to lactose. The results show that microbes in the colon are ready to make use of the lactose that reaches them.

Bacterial cooperation produces butyric acid
The study reveals an interplay within the gut: some bacteria break down the lactose molecule into simple sugars, while others go on to ferment them further. Particularly notable is the finding that the presence of lactose leads to increased production of butyric acid (butyrate).

Butyric acid is often formed when gut bacteria further process lactic acid. When the researchers compared the effects of lactic acid and butyric acid on the gut’s immune cells, butyric acid showed a markedly stronger effect.

Strengthening the balance of the immune system
The research findings indicate that butyric acid affects the antigen-presenting cells in the gut, enabling them to better handle dietary antigens. This is thought to play an important role in preventing the development of autoimmune reactions and allergies.

According to the researchers behind the project, the mechanistic insight from BioDairy could help dairy producers maintain their position in the market.

Read more in Mælkeritidende no. 5, published on 21 August – or see the digital version of the research article HERE.

By Maja Løvstrup
Photo: mejeri.dk/Niels Åge Skovbo