Low polyphenol content is on the pathway between ultra-processed food consumption and low-grade inflammation: cross-sectional analyses from the Moli-sani Study

Background and aims: Low-grade inflammation is one of the potential mechanisms linking ultra-processed foods (UPFs) to poor health outcomes. Besides having low nutritional composition, UPFs also lack bioactive compounds, such as polyphenols. We tested the hypothesis that low polyphenol content could be on the pathway of previously documented associations between UPFs and low-grade inflammation. Methods and results: Data were from 22,169 men and women (mean age 55.4y ±11.7) of the Moli-sani Study (2005-2010). Total polyphenol intake was estimated by matching food consumption with the Phenol-Explorer database and UPF was defined according to the Nova classification. Low-grade inflammation was assessed by a composite INFLA-score. Higher UPF intake was associated with lower dietary polyphenol content (β = -132.3; 95 % CI: -139.3, -125.4 mg/d), compared to the bottom category, and this inverse association was consistent for main polyphenol classes. An increasing consumption of UPFs was directly associated with higher values of the INFLA-score (β = 0.23; 95 % CI 0.10, 0.35); the inclusion of total dietary polyphenols into the multivariable model explained about 18 % of the direct relationship of UPF with the INFLA-score (p-value = 0.0038), and this association was particularly evident for lignans (proportion explained = 32.6 %; p-value = 0.0011). Conclusions: A higher dietary share of UPFs possibly provides lower amounts of polyphenols in the diet. The poor polyphenol content of highly processed foods explains a good proportion of the direct association of UPFs with low-grade inflammation. These findings emphasize the importance of limiting UPF consumption and increasing polyphenol-rich foods to reduce inflammation and possibly lower the risk of related chronic diseases.