Acute effects of nitrate and breakfast on working memory, cerebral blood flow, arterial stiffness, and psychological factors in adolescents: Study protocol for a randomised crossover trial

Callum Regan; Emerald G Heiland; Örjan Ekblom; Olga Tarassova; Karin Kjellenberg; Filip J Larsen; Hedda Walltott; Maria Fernström; Gisela Nyberg; Maria M Ekblom; Björg Helgadóttir

doi:10.1371/journal.pone.0285581

Acute effects of nitrate and breakfast on working memory, cerebral blood flow, arterial stiffness, and psychological factors in adolescents: Study protocol for a randomised crossover trial

PLoS One. 2023 May 19;18(5):e0285581. doi: 10.1371/journal.pone.0285581. eCollection 2023.

Authors

Callum Regan^{1

2}, Emerald G Heiland^{1

3}, Örjan Ekblom¹, Olga Tarassova⁴, Karin Kjellenberg¹, Filip J Larsen⁴, Hedda Walltott¹, Maria Fernström¹, Gisela Nyberg^{1

5}, Maria M Ekblom^{1

6}, Björg Helgadóttir^{1

7}

Affiliations

¹ Department of Physical Activity and Health, The Swedish School of Sport and Health Sciences (GIH), Stockholm, Sweden.
² Division of Physiotherapy, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden.
³ Department of Surgical Sciences, Medical Epidemiology, Uppsala University, Uppsala, Sweden.
⁴ Department of Physiology, Nutrition, and Biomechanics, The Swedish School of Sport and Health Sciences (GIH), Stockholm, Sweden.
⁵ Department of Global Public Health, Karolinska Institutet, Solna, Sweden.
⁶ Department of Neuroscience, Karolinska Institutet, Solna, Sweden.
⁷ Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, Solna, Sweden.

Abstract

Background: Inorganic nitrate has been shown to acutely improve working memory in adults, potentially by altering cerebral and peripheral vasculature. However, this remains unknown in adolescents. Furthermore, breakfast is important for overall health and psychological well-being. Therefore, this study will investigate the acute effects of nitrate and breakfast on working memory performance, task-related cerebral blood flow (CBF), arterial stiffness, and psychological outcomes in Swedish adolescents.

Methods: This randomised crossover trial will recruit at least 43 adolescents (13-15 years old). There will be three experimental breakfast conditions: (1) none, (2) low-nitrate (normal breakfast), and (3) high-nitrate (concentrated beetroot juice with normal breakfast). Working memory (n-back tests), CBF (task-related changes in oxygenated and deoxygenated haemoglobin in the prefrontal cortex), and arterial stiffness (pulse wave velocity and augmentation index) will be measured twice, immediately after breakfast and 130 min later. Measures of psychological factors and salivary nitrate/nitrite will be assessed once before the conditions and at two-time points after the conditions.

Discussion: This study will provide insight into the acute effects of nitrate and breakfast on working memory in adolescents and to what extent any such effects can be explained by changes in CBF. This study will also shed light upon whether oral intake of nitrate may acutely improve arterial stiffness and psychological well-being, in adolescents. Consequently, results will indicate if nitrate intake from beetroot juice or if breakfast itself could acutely improve cognitive, vascular, and psychological health in adolescents, which can affect academic performance and have implications for policies regarding school meals.

Trial registration: The trial has been prospectively registered on 21/02/2022 at https://doi.org/10.1186/ISRCTN16596056. Trial number: ISRCTN16596056.

Copyright: © 2023 Regan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Publication types

Clinical Trial Protocol
Research Support, Non-U.S. Gov't

MeSH terms

Adolescent
Adult
Beta vulgaris*
Blood Pressure
Breakfast
Cerebrovascular Circulation
Cross-Over Studies
Dietary Supplements
Humans
Memory, Short-Term
Nitrates
Pulse Wave Analysis
Randomized Controlled Trials as Topic
Vascular Stiffness*

Substances

Nitrates

Associated data

ISRCTN/ISRCTN16596056.

Grants and funding

This project is supported by The Knowledge Foundation https://www.kks.se/ (20180040; ÖE, GN), and the following companies COOP Sverige, IKEA, Skandia, Skanska, Generation Pep, and Konsumentföreningen Stockholm. Neither the funder nor the partner companies had a role in the design of the study, nor will they in data collection or analysis, interpretation of data, or in the preparation or writing of the manuscript.