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Fruit basket (apples, nectarines, strawberries). © INRA, FORT Francis

An original study in healthy individuals: impact of a high-fibre diet on the gut microbiota

The richness and stability of our gut microbiota - or in other words all the bacteria that we harbour in our digestive tract - are important parameters to ensure satisfactory functioning of the symbiosis between a human being and his or her gut ecosystem.  INRA scientists, working in collaboration with the Rhône-Alpes Centre for Research in Human Nutrition (CRNH) carried out a study in slim, healthy subjects receiving controlled intakes of dietary fibre.  The results showed that a more stable and richer microbiota (i.e. containing the greatest diversity of bacterial species) was seen in people consuming the greatest variety of high-fibre foods.

Updated on 06/09/2017
Published on 09/11/2015

Slim, healthy individuals living in the same geographical region of France were followed for eight weeks at the Rhône-Alpes Centre for Research in Human Nutrition in Grenoble. In the context of a balanced, omnivorous diet, they received menus prepared for the study which supplied a total of 10 g or 40 g of dietary fibre each day. When they were not receiving the 10 g and 40 g fibre menus (each for a period of five days) the subjects ate their normal diet.  They also completed a questionnaire which recorded their precise consumptions of fruits, vegetables and other sources of fibre. 

A complete analysis of the microbiota in these individuals was made by the INRA scientists in order to measure its structure and activity. The analysis of activity (metatranscriptomics) showed that an intake of 40 g fibre per day for just five days (versus 10 g) markedly increased the expression of Glycosyl Hydrolases (GH), the genes responsible for metabolising fibre, and reduced the expression of the GH involved in degrading mucins, protective polymers that are produced by the host.  In other words, increasing the fibre intake led to an increase in the degradation of fibres supplying beneficial compounds, and to protection of the intestinal mucosa, the physical barrier which plays an important role in our natural defences.  Furthermore, the greater the diversity of the microbiota, the more it was stable.

The results of this work should be seen in a future context of personalised nutrition, with guidelines adapted to the richness of each person's microbiota.  For example, in individuals with a microbiota that is little diverse, a dietary intake of varied fibres could improve it.  As for those with a rich microbiota, the challenge for the scientists is to understand how this can be sustained during the lifetime of a subject, despite the occurrence of environmental factors known to reduce microbiota biodiversity: use of antibiotics, inflammation, illness, weight gain or ageing.

An original study for two reasons:

- Very few studies have focused on the impact of diet on the microbiota in slim and healthy individuals, classic studies on dietary fibre having tended to demonstrate the impact of a compound on a single component (genus or species) in the microbiota.
- This is the first time the GitHub platform has been used by French biologists: it enables the sharing of all study data and of the computerised codes used to carry out bioinformatics and statistical analyses, thus enabling the complete traceability of this work.

Scientific contact(s):

  • Marion Leclerc (33 (0)1 34 65 24 64) INRA-AgroParisTech Joint Research Unit for Food and Gut Microbiology for Human Health (Institut Micalis)
Press Relations:
INRA News Office (33 (0)1 42 75 91 86)
Associated Division(s):
Microbiology and the Food Chain
Associated Centre(s):


Gut microbiota richness promotes its stability upon increased dietary fibre intake in healthy adults. Julien Tap, Jean-Pierre Furet, Martine Bensaada, Catherine Philippe, Hubert Roth, Sylvie Rabot, Omar Lakhdari, Vincent Lombard, Bernard Henrissat, Gérard Corthier, Eric Fontaine, Joël Doré and Marion Leclerc – Environmental Microbiology, online 3 September 2015. DOI: 10.1111/1462-2920.13006 

For more information on the Rhône-Alpes CRNH https://www.crnh-rhone-alpes.fr