8 2 / 2025 // LEOPOLDINA / NEWS
“ This ecosystem is like a network”
Nutritionist Dirk Haller talks about the microbiome at the Class III evening lecture
Dirk Haller is carrying out research at the Technical University of Munich / Germany on the interactions between the gut microbiome, nutrition and the immune system and how they influence diseases. The Professor of Nutrition and Immunology will discuss his studies at the Class III – Medicine evening lecture at the Leopoldina in Halle( Saale)/ Germany on 9 July.
Your lecture is titled“ The microbiome as an organ – fact or science fiction?”... Dirk Haller: … this is of course a slight provocation. It’ s not actually an organ I was born with.
It is a public lecture. Is that something you enjoy? Haller: I really like giving public lectures because it teaches me how to explain my research in an understandable way. And people often ask surprising questions to which you do not always have an answer. I am looking forward to it!
So the microbiome is not an organ. But what exactly does this biomass in the gut consist of? Haller: It consists of microbes, bacteria, fungi, viruses, archaea, the entire microbiological spectrum. And the exciting thing is that it is individual to each person. We enter the world in a sterile state and after birth a kind of free marketplace is created that is colonised by what we ingest. Microbes are genetically individual organisms, they fight for substrates, alliances and interactions occur, and after two or three years a relatively stable, individual ecosystem develops.
Dirk Haller.
Image: TU München
ity. The frequent use of antibiotics and almost every illness change the microbiome.
The question now is whether the connection is causal or not. This cannot be answered conclusively. In the case of Crohn‘ s disease, chronic intestinal inflammation, it is assumed that the change in the microbiome is the causal driver of the disease. But where does the initial trigger that changes the microbiome come from? Or does the disease change the ecosystem and this drives the disease further?
What about other diseases? Haller: There is good evidence for a causal interaction in bowel cancer. There
EVENING LECTURE
Munich-based nutritionist and food scientist Dirk Haller gives a fascinating insight into an“ organ” that is only acquired after birth and that becomes unbalanced when disrupted: the microbiome. His evening lecture on Wednesday, 9 July, from 6.30 p. m. at the Leopoldina in Halle( Saale) is part of the Class III – Medicine symposium. The evening lecture is in German only.
Evening Lecture
What is the connection between the microbiome and diseases? Haller: Its ecosystem is like a network; when I eat a pork knuckle, it expands and then swings back again. However, various factors can disrupt this stabilare also links to the metabolism, to the brain, and in degenerative diseases such as dementia there is an initial suspicion. Not every suspicion will be confirmed, but this microbial ecosystem is incredibly potent in its metabolic power. 70 to 80 per cent of our immunity is located in the gut.
Speaking of pork knuckle – is there a diet that will keep my microbiome healthy? Haller: Diet has a significant influence on the microbiome, that is for certain. We can now see this in a very differentiated way. If we add a single nutrient, we can see it in the data. However, it is still very difficult for me to say which diet you should use to nudge your microbiome into the healthiest possible category. It is a very individual thing.
But a special diet can help with Crohn’ s disease...? Haller: Yes, there is nutritional therapy for children using a special liquid diet. It’ s fascinating that children can achieve an inflammation-free state extremely quickly. And according to our current study it is plausible that this food does not have a direct effect on the inflammation but changes the microbiota.
You have a background in food microbiology. What motivates you in your research? Haller: In 2000 I carried out research at the Nestlé Research Centre in Lausanne. This type of research did not exist back then, and companies were thinking about probiotics for the first time. However, I wanted to get to the disease endpoint, where we are relatively certain that commensal bacteria, which are actually harmless, have a fundamental effect and can trigger a disease.
■ THE INTERVIEW WAS CONDUCTED BY CHRISTINE WERNER