Epidemiological studies have led to the recommendation of 30-40g fibre intake per day. However, there are thousands of different dietary fibres in our food some with unknown bioactive effects, making advice difficult. To simplify the variety of fibres the terms soluble and insoluble have been used for classification however these physical-chemical properties hardly correlate with physiological health effects.

The EU-funded FIBEBIOTICS (Dietary fibers supporting gut and immune Function - from polysaccharide compound to health claim) project investigated the influence of non-digestible polysaccharides (NPS) on immune system and gut function. The work focused on the effect of NPS on enhancing immune defence against pathogens, increasing the gut barrier function and reducing infectious diseases such as common cold and influenza.

To facilitate their research, scientists developed a toolbox of dedicated assays and in vitro screening methods to compare different NPS for their bioactivity towards gut and immune cells as well as on microbiota and their metabolites. They found that NPS could activate gut and immune cells which respond with the activation of immune-related genes like NFkB and secretion of chemokines to attract other immune cells to the place of action. Furthermore, they characterised, purified and processed NPS, and utilised the information to design new food products with NPS activity.

Considerable effort went into the mechanism of NPS degradation by gut or colon bacteria. Scientists showed that some NPS are more resistant to degradation, while in others, only part of the molecule gets degraded. In addition, they observed that different NPS ferment differently leading to different amounts and ratios of short chain fatty acids (SCFA), which are considered to have a positive health effect. To evaluate SCFA levels, part of the research focused on the development of a sensor that might be applied in vivo in the intestine. Besides that, several clinical trials have been performed to study the effect towards gut barrier function and immune parameters in humans.

Given that deregulation of the immune system can lead to autoimmune diseases, allergies and inflammation, it is of paramount importance to understand how to maintain or improve its function. The FIBEBIOTICS deliverables will help formulate the European Food Safety Authority guidelines accordingly in the future, so that food intervention could be used therapeutically.