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A specific dietary fibre supplementation improves cognitive performance—an exploratory randomised, placebo-controlled, crossover study



The impact of the microbiota on the gut-brain axis is increasingly appreciated. A growing body of literature demonstrates that use of dietary fibre and prebiotics can manipulate the microbiota and affect host health. However, the influence on cognition and acute stress response is less well understood.


The objective of this study was to investigate the efficacy of a dietary fibre, polydextrose (PDX), in improving cognitive performance and acute stress responses through manipulation of the gut microbiota in a healthy population.


In this double-blind, randomised, placebo-controlled, crossover design study, 18 healthy female participants received 12.5 g Litesse®Ultra (> 90% PDX polymer) or maltodextrin for 4 weeks. Cognitive performance, mood, acute stress responses, microbiota composition, and inflammatory markers were assessed pre- and post-intervention.


PDX improved cognitive flexibility as evidenced by the decrease in the number of errors made in the Intra-Extra Dimensional Set Shift (IED) task. A better performance in sustained attention was observed through higher number of correct responses and rejections in the Rapid Visual Information Processing (RVP) task. Although there was no change in microbial diversity, abundance of Ruminiclostridium 5 significantly increased after PDX supplementation compared with placebo. PDX supplementation attenuated the increase of adhesion receptor CD62L on classical monocytes observed in the placebo group.


Supplementation with the PDX resulted in a modest improvement in cognitive performance. The results indicate that PDX could benefit gut-to-brain communication and modulate behavioural responses.

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We thank Anne Marie Cusack for assistance in study visit and collection of biological samples; Danielle Dorland, Sara Hojabri, and Cassandra Morel for facilitating the socially evaluated cold pressor and initial sample processing; Eline Sundt and Con Moran for data entry; Grainne Cremin cortisol analysis; Prof. Paul Cotter, Dr. Fiona Crispie, and Ms. Laura Finnegan from the Teagasc Next Gen DNA Sequencing Centre for their role in relation to the 16S rRNA sequencing; as well as Dr. Panagiota Stamou, Dr. Ken Nally, and the APC Microbiome Ireland flow cytometry platform for their technical expertise. We would also like to thank Dr. Elaine Patterson and Dr. Arthur Ouwehand, DuPont Nutrition & Biosciences, for scientific input. Lastly, the authors would like to thank all the volunteers who participated in the study.


The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The dietary fibre was supplied by DuPont Nutrition & Biosciences as a gift. This study was funded in part by MyNewGut, an EU 7th Framework Programme under Grant Agreement 613979. The EU is not liable for the content presented in this publication. The study was also funded by APC Microbiome Ireland. APC Microbiome Ireland is a research centre funded by Science Foundation Ireland (SFI), through the Irish Government’s National Development Plan (grant no. 12/RC/2273).

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Authors and Affiliations



K.B. contributed to the data analysis, interpreted the data, and drafted the manuscript. C.M.L.S. designed the intervention study, performed the participant visits, advised on data analysis and interpretation, and contributed to the drafting of the manuscript. C.C. contributed to the analysis of the psychological questionnaires and CANTAB as well as to data analysis and interpretation. T.F.S.B. performed the bioinformatics for the microbiota data. N.W. performed DNA extraction, library preparation, and microbiota sequencing. C. R. S. contributed to biological analyses. M.vd.W performed the blood inflammatory profile analysis and interpreted the data. F.F. contributed to library preparation and microbiota sequencing. C.S. contributed to study design and data interpretation. JFC and TGD contributed to the design of the study, interpreted the data, and contributed to writing of the manuscript. All authors approved the final version of the manuscript. CC, TFSB, MvdW, and NW contributed equally to this work.

Corresponding author

Correspondence to John F. Cryan.

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Conflict of interest

APC Microbiome Ireland has conducted studies in collaboration with several companies, including GSK, Pfizer, Cremo, Wyeth, Mead Johnson, Nutricia, 4D Pharma, and DuPont. T. G. D. has been an invited speaker at meetings organized by Servier, Lundbeck, Janssen, and AstraZeneca and has received research funding from Mead Johnson, Cremo, Wellness, Nutricia, and 4D Pharma. J. F. C. has been an invited speaker at meetings organized by Mead Johnson, Yakult, and Alkermes, and has received research funding from Mead Johnson, Cremo, Nutricia, and DuPont. C.S. has been an invited speaker at meetings organized by Nutricia and received research funding from Mead Johnson, Cremo, Nutricia, and DuPont. All other authors report no conflict of interest.

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Kirsten Berding and Caitriona M. Long-Smith are co-first authors

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Berding, K., Long-Smith, C.M., Carbia, C. et al. A specific dietary fibre supplementation improves cognitive performance—an exploratory randomised, placebo-controlled, crossover study. Psychopharmacology 238, 149–163 (2021).

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  • Microbiota
  • Short-chain fatty acids
  • Dietary fibre
  • Prebiotic
  • Polydextrose
  • Cognition
  • Stress
  • Inflammation