Introduction: Age-related cognitive decline is a leading cause of disability in the UK, with incidences projected to triple by 2060. With no effective disease-modifying therapies currently available, modifiable lifestyle factors—which account for up to 35% of dementia risk—offer a promising approach to slow cognitive ageing. Diets rich in flavonoids have been linked to better cognitive outcomes, and acute high-flavanol cocoa supplementation has been shown to transiently improve cognitive function in young adults. However, it remains unclear whether these benefits can be sustained, or further enhanced, through daily, chronic supplementation. This study therefore aims to investigate the effects of both acute and chronic high-flavanol cocoa supplementation on cognitive performance in healthy young adults, providing crucial insights into dietary strategies for maintaining brain health.
Methods: In this double-blind, placebo-controlled, parallel, randomised trial, 50 healthy young adults (18 – 40 years; gender-balanced) were supplemented daily for 8 weeks with either high-flavanol cocoa (15.5 g; 792.33 mg total flavanols, 137.65 mg monomeric flavanols, e.g., (-)-epicatechin) or low-flavanol cocoa (15.5 g; 30.12 mg total flavanols, 18.13 mg monomeric flavanols). Cognitive function was assessed using the Stroop Task, Modified Attention Network Task (MANT), and Task Switching Task (TST) at four timepoints: (i) day 1, before supplementation (0 h; baseline); (ii) day 1, 2 h after supplementation (acute effect); (iii) ~ day 56, before supplementation (chronic effect); and (iv) ~ day 56, 2 h after supplementation (acute-within-chronic effect). All procedures were conducted in accordance with relevant ethical guidelines and regulatory standards. This study is registered with the ISRCTN clinical trials registry (ISRCTN29176549).
Results: All participants (N = 50; mean age: 23.36 ± 4.74 years, mean BMI: 25.59 ± 15.33 kg/m2) have completed the intervention. Data analysis is currently ongoing, with results expected the be fully analysed by time of presentation. Data will be analysed using a linear mixed model with intervention (high- or low-flavanol cocoa), time (at the acute, chronic, and acute-within-chronic timepoints), and their interaction as fixed effects, baseline values as a covariate, and participants included as a random effect.
Conclusion: As the population ages, preserving brain health has become a major public health priority. Outcomes of this study will establish if benefits in cognition in young adults are apparent beyond acute effects, with the focus of future work extending to older adults. The findings will help inform evidence-based dietary strategies for mitigating age-related cognitive decline and support public health recommendations for healthy ageing.
Keywords: cocoa flavanols, flavonoids, cognition function, executive function