Estimation of polyphenol intake and the association with cognitive performance in UK women

Interest in estimating polyphenol intake and identification of the major dietary sources of polyphenols have risen in tandem with the reporting of certain health benefits of polyphenols, but only a few studies have reported polyphenol intake in the UK population. This thesis, therefore, aims to address this research gap amongst a sample of 246 UK women aged 18-50 years. A food diary was used to estimate food intake, and only ingredients with a polyphenol content of ≥ 1 mg per portion of food were included for estimation of polyphenol intake. Missing data for polyphenol content in some foods was determined by using the Folin-Ciocalteu assay and performing HPLC analysis. The polyphenol intake of the studied population was 1089 ± 814 mg/day. Tea and coffee were the major polyphenol sources while fruit, vegetables and confectionaries were other important sources of polyphenols. Age was the main predictor of flavonoid, phenolic acid and total polyphenol intake, with the increasing age associated with higher consumption. Cognitive performance was assessed using selected cognitive tests in a sub sample of the participants (Diet and Health study). Participants at the lowest quartile of polyphenol intake and who were non-consumers of coffee or tea were younger and have showed better performance on spatial memory assessed from Visual Spatial Learning Test (VSLT) (p<0.01). Age was an important predictor for both polyphenol intake and cognitive performance and partly explains the minor contribution of polyphenol intake to the cognitive performance of the studied population. This study has contributed to the understanding of the relationship between polyphenol intake and cognitive performance.