Current Evidence on the Effect of Dietary Polyphenols Intake on Brain Health

Abstract

Background: In recent years, the possibility of favorably influencing the cognitive capacity through the promotion of lifestyle modifications has been increasingly investigated. In particular, the relationship between nutritional habits and brain health has attracted special attention. Polyphenols are secondary metabolites of plants. These phytochemicals are present in vegetables, fruits, legumes, olive oil, nuts. They include several antioxidant compounds and are generally considered to be involved in defense against chronic human diseases. In recent years, there has been a growing scientific interest in their potential health benefits to the brain. Objective: In this mini-review, we focus on the current evidence defining the position of polyphenols dietary intake in the prevention/slowdown of human neurodegenerative diseases. Methods: A literature research was performed using the keywords “polyphenols”, “brain”, “nutrition”, individually or all together, focusing on human trials. Results: The available clinical studies on the effect of polyphenols on cognitive functions are quite convincing. Regular dietary intake of polyphenols would seem to reduce the risk of neurodegenerative diseases. Moreover, beyond their beneficial power on the central nervous system, these phytochemicals seem also to be able to work on numerous cellular targets. They show different biological actions, that however, have to be confirmed in long-term randomized clinical trials. Currently, most data propose that a combination of phytonutrients instead of any single polyphenol is responsible for health benefits. Conclusions: Evolving indications suggest that dietary polyphenols may exercise beneficial actions on the central nervous system, thus representing a possible tool to preserve cognitive performance. Key questions to improve the coherence and reproducibility in the development of polyphenols as a possible future therapeutic drug require a better understanding of the sources of polyphenols, their treatment and more standardized tests including bioavailability of bioactive metabolites and studies of permeability of the brain.