ORIGINAL RESEARCH article
Front. Nutr.
Sec. Nutrition, Psychology and Brain Health
Effects of lifestyle intervention and supplementation with insoluble oat fiber on cognitive functions in patients with prediabetes – a secondary analysis of the Optimal Fiber Trial (OptiFiT)
Provisionally accepted
Stefan Kabisch1*
Federico Montagna1Caroline Honsek2Margrit Kemper2Christiana Gerbracht2Ayman M. Arafat1
Andreas Birkenfeld3Ulrike Dambeck2Martin A. Osterhoff2Martin O. Weickert4Agnes Flöel5
Andreas F.H. Pfeiffer1- 1Department of Endocrinology and Metabolic Medicine, Charité University Medicine Berlin, Berlin, Brandenburg, Germany
- 2Deutsches Institut fur Ernahrungsforschung Potsdam-Rehbrucke, Nuthetal, Germany
- 3Eberhard Karls Universitat Tubingen, Tübingen, Germany
- 4Coventry University, Coventry, United Kingdom
- 5Universitat Greifswald, Greifswald, Germany
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Effects of lifestyle intervention and supplementation with insoluble oat fiber on cognitive functions in patients with prediabetes – a secondary analysis of the Optimal Fiber Trial (OptiFiT) Correspondence to Stefan Kabisch, Stefan.kabisch@charite.de Background: In cohort studies, intake of insoluble cereal fiber is associated with multiple health benefits, including preserved cognitive functions. Evidence from intervention studies is sparse, however. In the Optimal Fibre Trial (OptiFiT) lifestyle changes and supplementation with oat fiber in prediabetes patients improved glycemic metabolism and body composition, which could be linked to cognitive changes. Methods: In OptiFiT, 180 patients with impaired glucose tolerance received either an insoluble fiber supplement or placebo for two years in a double-blind, randomized approach, and underwent a parallel one-year complex lifestyle intervention program. Annual visits included metabolic, anthropometric and cognitive assessments: Mini-mental state examination (MMSE), verbal learning memory test (VLMT), Regensburg word fluency test (RWFT), number connection test (NCT), number recall test (NRT), and Rey-Osterrieth Complex Figure Test (RCFT). Group-wise comparisons were conducted both globally as well as stratified by age. Results: Cognitive functions only slightly improved – particularly in VLMT and RWFT – without major differences by group or age. At baseline, cognitive function measured by RCFT recall, VLMT, RWFT and backwards NRT was inversely correlated with age, but not with HbA1c, fasting or postprandial glucose levels. Conclusions: Beneficial effects of insoluble fiber and lifestyle intervention on glycemia might not translate into preserved cognitive capabilities in middle-to-higher aged
Keywords: prediabetes, Diabetes Prevention, Insoluble fiber, Memory, Cognition, Learning, Impaired glucose tolerance, type 2 diabetes
Received: 08 Sep 2025; Accepted: 28 Nov 2025.
Copyright: © 2025 Kabisch, Montagna, Honsek, Kemper, Gerbracht, Arafat, Birkenfeld, Dambeck, Osterhoff, Weickert, Flöel and Pfeiffer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Stefan Kabisch
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