The effect of blueberry fruit on cognitive performance and mood: A systematic investigation of randomized controlled studies

Blueberries are a fruit rich in polyphenols that may be beneficial for cognitive performance and mood. This systematic review aims to examine the available evidence from randomized controlled trials investigating the potential effects of blueberry consumption on cognitive performance and mood in humans. Within the scope of the literature review, data from 2012 and onwards were searched using search engines such as PubMed, Google Scholar and Science Direct. In the study, randomized controlled and experimental studies were searched using the keywords blueberry, Vaccinium myrtillus L., cognition, cognitive, neuropsychology, dementia, Alzheimer's, mood, memory in English and Turkish. This systematic review excluded all articles on the effect of blueberry consumption on cognition and mood that were not randomized-controlled, non-experimental and used different berries. The inclusion criteria for the systematic review were PICOS (P: Characteristics of participants, I: Interventions, C: Comparison groups, O: Outcomes, S: Results) and a total of 19 articles were identified. In 10 studies included in the systematic review, blueberry consumption was effective in improving some cognitive performance measures such as short- or long-term memory and executive function in the elderly and children. While 2 different studies showed a positive effect of blueberries on mood in young adults and adolescents, 3 studies did not report improvement in the mood of the participants (one study on children, 2 studies on the elderly), which may be due to the fact that the mechanism of cognitive and mood effects of blueberries is not sufficiently known. In 4 studies, blueberries did not improve cognitive development. Based on the available evidence, blueberry fruit may improve some measures of cognitive performance. However, more data with similar blueberries and consistently reported cognitive performance tools in diverse populations are needed. Keywords: Antioxidant, Cognitive performance, Mood, Blueberry.