Relationship between dietary flavan-3-ols intake and mortality in metabolic syndrome population; a large cohort study.

Background: Metabolic syndrome (MetS) is a global health concern linked to increased mortality. Diets rich in plant-derived compounds, such as polyphenols, have shown potential health benefits for MetS. Among these, flavan-3-ols, a class of commonly occurring polyphenolic compounds, are known for their antioxidant and anti-inflammatory properties. Therefore, we hypothesize that flavan-3-ols intake is negatively associated with mortality risk in MetS population.

Methods: This study analyzed NHANES data (2007-2008, 2009-2010, and 2017-2018). Flavan-3-ol and monomer intake were obtained from the USDA Flavonoid and FNDDS databases. Associations with mortality were assessed using Cox regression, survival differences were compared using Kaplan-Meier curves, and non-linear trends were examined using restricted cubic splines. Subgroup analyses were conducted to explore potential effect modifications.

Results: Over a median follow-up period of 114 months, 1,856 participants survived, while 329 deaths were recorded. In Model 3, participants in the highest tertile (T3) of flavan-3-ol intake exhibited a 33% lower risk of all-cause mortality compared to those in the lowest tertile (T1) (HR = 0.67, 95%CI: 0.49-0.92). For monomers, the hazard ratios ranged from 0.55 for higher levels of epigallocatechin to 0.71 for higher levels of gallocatechin. Kaplan-Meier curves indicated significant differences in survival status across dietary flavan-3-ol intake groups. However, no association was found between flavan-3-ol intake and cardiovascular mortality risk. Additionally, restricted cubic spline (RCS) analysis did not reveal any non-linear relationship, and no significant interaction effects were observed in the subgroup analysis.

Conclusion: Higher dietary intake of flavan-3-ols is negatively associated with mortality risk in MetS population.