Polyphenols are types of phytochemicals found in plants that may reduce risk of certain chronic diseases, including cancers, type 2 diabetes, and cardiovascular disease. There exist different types of polyphenols: flavonoids, phenolic acids, stilbenes, lignans. The below study looks at all classes and 22 subclasses of polyphenols and risk of differentiated, papillary, and follicular thyroid cancers.
Polyphenol intake and differentiated thyroid cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) Cohort
This study included over 470,000 participants from The European Investigation into Cancer and Nutrition (EPIC) cohort from 10 countries in Europe. Polyphenol intake was estimated using dietary questionnaires and a Phenol-Explorer database at baseline, and differentiated, including subtypes papillary and follicular, thyroid cancers were compared at 14 years of follow-up.
The authors found:
1. Coffee, tea, fruits, and wine were main food sources of polyphenol intake
2. No association between total polyphenol intake and risk of overall differentiated, papillary, or follicular thyroid cancers
3. No associations between flavonoids, phenolic acids, stilbenes, lignans, or subclasses of polyphenols and risk of differentiated, papillary, or follicular thyroid cancers
4. In individuals who were overweight or obese (BMI greater than or equal to 25), an association between increased intake of polyphenols and phenolic acids and decreased risk of differentiated thyroid cancers
For the Patient and Caregiver
Foods with polyphenols include: spices, cocoa powder and dark chocolate, berries, beans, nuts, certain vegetables, coffee, tea, and red wine. Consumption of whole plant-based foods rich in fiber, of which some may also contain polyphenols, is encouraged for improved digestive function and cholesterol, as well as decreased risk of certain types of cancers. Intake of foods rich in polyphenols may be beneficial in those who are overweight or obese to decrease risk of differential thyroid cancers.
For the Healthcare Team
Counsel patients on the importance of consumption of plant-based foods for decreased risk of chronic disease. When working with those with a BMI over 25, highlight polyphenol rich foods. Obesity is a low-grade inflammatory disease, and excess adiposity and inflammation are risk factors for thyroid cancer. This may explain the relationship found in the present study, as polyphenols have anti-inflammatory and anti-obesity properties. Of note, change in polyphenol intake over the 14 years was not captured in this study, as intake was measured at baseline, which should be considered in further studies.
[i] Zamora-Ros R, Cayssials V, Franceschi S, Kyro C, Weiderpass E, Hennings J…Rinaldi S. (2019). Polyphenol intake and differentiated thyroid cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) Cohort. Int J Cancer. doi: 10.1002/ijc.32589.