High concentrations of a urinary biomarker of polyphenol intake are associated with decreased mortality in older adults

Abstract

Polyphenols might have a role in the prevention of several chronic diseases, but evaluating total dietary polyphenol (TDP) intake from self-reported questionnaires is inaccurate and unreliable. A promising alternative is to use total urinary polyphenol (TUP) concentration as a proxy measure of intake. The current study evaluated the relationship between TUPs and TDPs and all-cause mortality during a 12-y period among older adult participants. The study population included 807 men and women aged 65 y and older from the Invecchiare in Chianti study, a population-based cohort study of older adults living in the Chianti region of Tuscany, Italy. TUP concentrations were measured at enrolment (1998-2000) using the Folin-Ciocalteau assay after a solid-phase extraction. TDPs were also estimated at baseline throughout a validated food frequency questionnaire and using our database based on USDA and Phenol-Explorer databases. We modeled associations using Kaplan-Meier survival and Cox proportional hazards models, with adjustment for potential confounders. During the 12-y follow-up, 274 participants (34%) died. At enrollment, TUP excretion adjusted for age and sex tended to be greater in participants who survived [163 ± 62 mg gallic acid equivalents (GAE)/d)] than in those who died (143 ± 63 mg GAE/d) (P = 0.07). However, no significant differences were observed for TDPs. In the multivariable Cox model, participants in the highest tertile of TUP at enrolment had a lower mortality rate than those in the lowest tertile [HR = 0.70 (95% CI: 0.49-0.99); P-trend = 0.045], whereas no significant associations were found between TDP and overall mortality. TUP is an independent risk factor for mortality among community-dwelling older adults, suggesting that high dietary intake of polyphenols may be associated with longevity.

FIGURE 1

Kaplan-Meier plots of all-cause mortality for 12 y of follow-up in the InCHIANTI study by tertiles of TUPs (log-rank = 29.44; P < 0.001 by log-rank test between extreme tertiles) (A) and TDPs (log-rank = 3.30; P = 0.19) (B). GAE, gallic acid equivalent; InCHIANTI, Invecchiare in Chianti; TDP, total dietary polyphenol; TUP, total urinary polyphenol.