2012 marked the launch of the Flemish Gut Flora Project, initiated by prof. Jeroen Raes (VIB/VUB/KU Leuven). Together with his team, prof. Raes aimed at the ambitious task of mapping the gut flora composition of around 5,000 volunteers in Flanders (Belgium). The purpose of this endeavor was to investigate links between the human gut flora and health, diet, and lifestyle.
Prof. Raes' study has identified 69 factors associated with gut flora composition and diversity. Most of these covariates are related to transit time, health, diet, medication, gender, and age. Integration of the Flemish Gut Flora Project results with other data sets gathered around the world revealed a set of 14 bacterial genera that make up a universal core microbiota present in all individuals.
Beer and buttermilk
Stool transit time showed the strongest association to gut flora composition. Also diet was an important factor, with most associations related to fiber consumption. One of the many surprising findings was the association of a particular bacterial group with a preference for dark chocolate! "The Belgian chocolate effect.", Raes laughs. "As many readers might expect, we also found an association between gut flora composition and beer consumption." Other project results incite deeper investigation, such as the relationship between the gut flora and factors linked to oxygen uptake capacity. Medication also had a strong link to the gut flora profile. The Raes Lab researchers not only identified associations with antibiotics and laxatives, but also with hay fever drugs and hormones used for anticonception or alleviation of menopause symptoms. Remarkably, early life events such as birth mode or whether or not volunteers were breast-fed as babies were not reflected in adult microbiota composition.
Tip of the iceberg
Although the Flemish Gut Flora Project has enormously enriched our knowledge on gut flora composition, it only allowed to explain 7% of gut flora variation. An enormous amount of work still needs to be done in order to sketch out the entire gut flora ecosystem. The Raes Lab estimates that around 40,000 human samples will be required just to capture a complete picture of gut flora biodiversity. In other words: we are only seeing the tip of the iceberg. And although the VIB team revealed a wide range of associations, further research is required to unveil what is cause and what is consequence.