Patrice D. Cani is a researcher and Professor from the Belgian Fund for Scientific Research (FRS-FNRS) and team leader in the Metabolism and Nutrition research group at the Université catholique de Louvain’s Brussels-based Louvain Drug Research Institute. He was one of the scientists who came up with the concept of a prebiotic while working at Nathalie Delzenne’s and Marcel Roberfroid’s lab at the Université catholique de Louvain. Nowadays, he investigates the role played by the gut microbiota in the onset of diabetes, obesity and low-grade inflammation. More specifically, he researches the link between gut microbiota, the host and some biological systems, in the context of metabolic diseases. Cani was one of the main speakers at the Bdebate conference held at the beginning of July at the Cosmocaixa science museum in Barcelona, where he was interviewed by

What is a probiotic?

A probiotic consists of living bacteria that is ingested and provides a beneficial impact. Probiotics can be added, for instance, to milk or are present in yogurt or other fermented milks, or you can also have pills containing living bacteria. This is the scientifically-agreed definition, but then we also have fermented products that are not actually called probiotics (as they are not accepted by the European Food Safety Authority (EFSA) as such) but which would definitely have a beneficial impact on health. It is still an open area and the definition itself may well be reviewed.

Do different probiotics have different effects on the microbiota?

We cannot really bring together probiotics as a whole and say they all have the same impact. What has been studied and shown with regards to a specific strain cannot be extrapolated to another. Probiotics contained in food or pills can, of course, have similar effects, for instance protecting or reducing the risk of diarrhoea when taking a course of antibiotics. In rodents and humans some probiotics have been shown to have an impact on reducing inflammation or changing glycaemia, but, again, you cannot say that all probiotics will have the same effect.

If a person is healthy, should he or she take probiotics?

We can ingest probiotics or prebiotics to improve the development of some diseases or even to challenge the immune system. I am pretty convinced that we have lots of stress in our daily lives and we don’t know when we will become ill, so if you can at least reduce or prevent symptoms by having consumed pro- and prebiotics, I think that is worth considering. I myself am definitely “pro-pro and prebiotics”.

Part of your work focuses on diabetes or obesity. What is the role of microbiota in these diseases?

First of all, we cannot prevent obesity and diabetes by consuming probiotics. Having said that, I think that as soon as we have identified the right bacteria or bacterial combination, and we have scientific studies regarding this issue, it will be very useful in preventing or reducing the onset of some diseases. So far, however, I am truly convinced we can use them at least to challenge the immune system, to make it aware of its environment and its capacity to respond to an aggression caused by bacteria, virus and so on. It has already been shown that different probiotic bacteria have a beneficial impact on the response to viruses or infections, due to this interaction between our immune system and the bacteria. But we are still at the beginning of the story, understanding how it works is a major challenge. We don’t know everything about the interaction between bacteria and host or host and microbiota. We have evidence that shows they seem to be efficient at least for diarrhoea and different infections. For other diseases like obesity and diabetes or even autism, causality is not yet clear. These are more complex problems that require more than simply changing the microbiota. And I’m saying that even while working in and contributing to the field.

Several studies have, indeed, outlined a relationship between gut microbiota and diseases like obesity and diabetes.

The link between microbiota and diabetes or obesity is not clear, but they share some patterns. For instance, one of the common factors is linked to the immune system or low-grade inflammation. So I am convinced that numerous other diseases, like arthritis, might also be associated with the gut microbiota, because they have the same common origin – low-grade inflammation. If inflammation comes from the translocation of bacteria or components from the microbiota and the gut into the bloodstream, you have the same response. In short, for me, the common points are the immune system’s response and probably the translocation of some components from the gut into the bloodstream.

How does microbiota affect gut permeability?  

It could be affected by different mechanisms. We have, for instance, shown that obesity and diabetes can disrupt the gut barrier at different levels. You have protein that maintain the cells tightly joined to each other; you also have a mucus layer and antimicrobial peptides produced by the host that keeps the bacteria at a distance. All these factors may be altered in the context of obesity or inflammation. Any alteration of the gut barrier, can lead to the translocation of components from bacteria into the bloodstream, which will trigger low-grade inflammation. The real origin and why it happens in obesity and diabetes is not yet established.