Blood concentrations of polyphenols are not clearly related to the risk of thyroid cancer

Polyphenols are bioactive compounds found primarily in plant-based foods such as fruits, vegetables, coffee, tea, cocoa and wine.

Although polyphenols have shown anticarcinogenic activity in previous in vitro studies, the epidemiological study led by IDIBELL and the ICO has found no association between their concentration in blood and thyroid cancer.

Only three specific polyphenols, related to the consumption of coffee and whole grains, have shown a certain tendency to reduce the risk of papillary thyroid cancer, results that should be confirmed in future studies.


Thyroid cancer is one of the most common endocrine cancers, in recent times its incidence has been gradually increasing and is up to three times more frequent in women than in men. Few risk factors related to this type of cancer are known, the most prominent being excess of weight, exposure to radiation or benign diseases of the thyroid gland. However, the role of diet in thyroid carcinogenesis is still largely unknown.

Polyphenols are compounds present in foods of plant origin that have been shown to have an anticarcinogenic effect in cell and animal models. Its biological properties include antioxidant or anti-inflammatory effects. In addition, they have been shown to induce cell death and stop the proliferation of thyroid cancer cells. Despite the promising results of these in vitro and in vivo studies, epidemiological and human clinical studies that demonstrate the association of these polyphenols with a lower risk of developing thyroid cancer are lacking. The few approaches that link polyphenols and thyroid cancer are made by measuring exposure through dietary surveys, with the accuracy limitations that this entails.

A study led by the nutrition and cancer group of the Bellvitge Biomedical Research Institute (IDIBELL) and the Catalan Institute of Oncology (ICO), has evaluated the relationship between blood concentrations of polyphenols and the risk of developing thyroid cancer. “The objective of the study was to determine if polyphenols could have a preventive role in thyroid cancer and if their detection in blood represented a more reliable measure than questionnaires,” says Dr. Raül Zamora, leader of the project.

The work, published in The American Journal of Clinical Nutrition, has analyzed the level of polyphenols in the blood of 785 women with and without thyroid cancer, from the European EPIC (European Prospective Investigation into Cancer and Nutrition) cohort. Results show that there is no clear association between the consumption of polyphenols and the risk of developing this type of cancer. However, the study detects three specific polyphenols related to the consumption of coffee and whole grains: caffeic acid, 3,4-dihydroxyphenylpropionic acid, and ferulic acid, which seem to be related to a lower incidence of thyroid cancer, specifically the papillary subtype. “Although the results of this study are not conclusive, the focus is on these compounds to deepen their research in future studies,” says Dr. Zamora.


Original paper:

Zamora-Ros R, Lujan-Barroso L, Achaintre D, [32 authors], Scalbert A, Rinaldi S, Agudo A. Blood polyphenol concentrations and differentiated thyroid carcinoma in women from the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Am J Clin Nutr. 2020 Oct 6:nqaa277. doi: 10.1093/ajcn/nqaa277.

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