Can Improving the Nutritional Content of Bread Enhance Cognition? Cognitive Outcomes from a Randomized Controlled Trial

  • Naomi White
  • Phoebe Naldoza-Drake
  • Katherine Black
  • Luke Scullion
  • Liana MachadoEmail author
Original Research


Past research indicates that dietary alterations involving increases in nuts or beetroot, or decreases in salt, may have the potential to enhance cognitive functioning. The current study reports cognitive outcomes from a 12-week randomized controlled parallel intervention trial designed to evaluate the effectiveness of manipulating these ingredients in a dietary staple, bread. Participants were recruited from Dunedin, New Zealand, between February 2015 and March 2017. Initial inclusion criteria required at least one indicator of metabolic syndrome and daily consumption of at least six slices of bread, but these criteria were relaxed 6 months into the study due to recruitment difficulties. In total, 196 participants were randomized (using minimization by age group, sex, and body mass index) to consume one of four breads (hazelnut, beetroot, low salt, or a control white bread). Participants completed a computerized cognitive test battery and physiological testing at four points during the intervention. Analyses focused on 102 participants (aged 18–73 years) who finished the intervention and completed pre- and post-intervention cognitive testing. Participants who consumed the experimental breads showed no evidence of cognitive improvement relative to the control group. Furthermore, the expected physiological changes did not occur, and participants reported poor compliance. Our findings suggest that participants may have changed their eating habits during the intervention period such that they consumed less bread and ingested other counteracting nutrients, rendering the intervention ineffective. Insight from this study can be used to guide the design of future dietary interventions.


Cognitive performance Dietary intervention Salt Beetroot Nuts 



The authors thank Georgia Best, Kirstin Bierre, Georgia Cowan, Stephanie Glover, Chris Gorman, Grace Killmer, Saejung Oh, Laura Thompson, Scott van Heerden, and the Human Nutrition team for their assistance with this project.

Funding Information

This research was supported by a Health Research Council of New Zealand Emerging Researcher First Grant awarded to Katherine Black (#14/581), and a Neurological Foundation of New Zealand Small Project Grant (#1537-SPG) awarded to Liana Machado.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.

Supplementary material

41465_2019_149_MOESM1_ESM.docx (16 kb)
Table S1 (DOCX 16 kb)


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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Department of Psychology and Brain Health Research CentreUniversity of OtagoDunedinNew Zealand
  2. 2.Brain Research New ZealandDunedinNew Zealand
  3. 3.Department of Human NutritionUniversity of OtagoDunedinNew Zealand

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