Higher dietary polyphenol intake is associated with lower blood inflammatory markers.

BACKGROUND: Evidence suggests a link between polyphenol intake and reduced incidence of several chronic diseases. This could arise through associations between polyphenol intake and reduced systemic oxidative stress and subsequent inflammation. However, confirming this association is difficult, as few large cohorts allow for comprehensive assessments of both polyphenol intake and markers of systemic inflammation.

OBJECTIVE: To address this, polyphenol intake was assessed in the UK-based Airwave cohort using 7-day diet diaries and data from Phenol-Explorer to test for associations between polyphenol intake and blood biomarkers of inflammation.

DESIGN: Participants included 9008 males and females aged 17-74 (median age 42) whose data was included in a cross-sectional analysis. Phenol-Explorer was used to estimate individuals' polyphenol intake from diet data describing the consumption of 4104 unique food items. C-reactive protein (CRP) and fibrinogen were used as blood biomarkers of inflammation.

RESULTS: There were 448 polyphenols found in reported diet items. Median total polyphenol intake was 1536 (1058-2092) mg/d. Phenolic acids and flavonoids were the main types of polyphenols, and non-alcoholic beverages, vegetables, and fruit were the primary sources. Variation in energy-adjusted polyphenol intake was explained by age, sex, salary, BMI, education level, smoking, and alcohol consumption. Linear regressions showed inverse associations between total daily intake and both CRP (β = -0.00702, P <0.001) and fibrinogen (β = -0.00221, P = 0.038). Associations with specific polyphenol compound groups also were found. Logistic regressions using total polyphenol intake quartiles showed stepwise reductions in the odds of elevated CRP with higher intake (6%, 23% and 24% versus quartile 1; P = 0.003), alongside 3% and 7% lower odds per unit of polyphenol consumption equivalent to 1 cup of tea or coffee per day.

CONCLUSIONS: This study describes polyphenol intake in a large, contemporary UK cohort. We observed associations between higher intake and lower CRP and fibrinogen. This contributes to evidence supporting the health benefits of dietary polyphenols.