Most plant-based foods are rich in polyphenols, components with antioxidant and anti-inflammatory properties. There are many types, present in various types of food: isoflavones, rather present in soy, or phenolic acids, mostly in coffee, are some examples. It seems that these compounds could have beneficial properties for health, even helping to regulate body weight or blood glucose levels.

That is why it is not ruled out that these molecules may participate in the management of the risk of cardiovascular diseases, cancer or type II diabetes. Along these lines, a research team from IDIBELL-ICO led by Dr. Delphine Casabonne and Dr. Raúl Zamora wanted to delve into the potential positive properties of polyphenols, and see what effect they may have on the development of a heterogeneous group of hematological cancers: lymphoid neoplasms. The study, with Dr. Enrique Almanza and Dr. David Guananga as first authors and recently published in the British Journal of Cancer, is the first ever done to investigate the association between polyphenol intake and the risk of developing lymphomas with a large European population.

Lymphoid neoplasms, a heterogeneous group of blood cancers

Lymphoid neoplasms are an extremely heterogeneous group of haematological tumours that develop in lymphocytes, cells of the immune system responsible for protecting us against infections, among other functions.

“There are more than 75 types of lymphoid neoplasms, more or less aggressive, with radically different treatments and prognoses,” explains Dr. Delphine Casabonne, principal investigator of CIBERESP and IDIBELL-ICO, an expert in the epidemiology of lymphoid neoplasms and co-director of the study. “The fact that they are so different makes it difficult to study, but more research is needed to understand how they develop and how we can prevent them. We know of few modifiable risk factors for these cancers. Therefore, studies like this are important to identify new potential risk or protective factors,” she concludes.

The EPIC cohort, a European effort to study diet and cancer

The study by the IDIBELL-ICO group has been carried out within the framework of the European EPIC (European Prospective Investigation into Cancer and Nutrition) cohort: a European collaborative project started in the 90s where more than 350,000 people were recruited, from 7 different countries, who have been followed for an average of 14 years to investigate the relationships between diet,   lifestyles, genetics, cancer, and other chronic diseases. The large dimensions of the EPIC study have made it possible to identify 2,394 participants who have developed lymphoid neoplasms during follow-up. Dietary polyphenol intake was compared between those who did and those who did not develop cancer, to see if there were significant differences. In addition, the enormous amount of data collected in the EPIC study also allowed us to explore this relationship in less frequent lymphoid neoplasm subtypes.

Epidemiological studies: leaving the laboratory to test hypotheses

In recent decades, more and more research groups have embarked on the study of polyphenols and their properties, especially in experimental studies with cell cultures and experimental animals. But until now there was little epidemiological data to support what was seen in the laboratory. More so in the case of the development of lymphoid neoplasms, where studies are very limited.

Now, the study by the team formed by the Infections and Cancer and Nutrition and Cancer groups of IDIBELL-ICO has made it possible to lay the first stone on the path of this line of research. Mostly, there seems to be no clear association between polyphenol intake and the risk of developing lymphoid neoplasms. However, going into detail and analysing the specific relationships of some subclasses of polyphenols, two possible associations have been detected: on the one hand, isoflavones, the polyphenols of soy, would have a certain protective action by slightly reducing the risk of lymphomas; and, on the other hand, the high consumption of some phenolic acids, present in coffee, would be related to an increased risk of Hodgkin’s lymphoma.

“The associations we have found are a good starting point, but we must place them in their context and complement our observations with other studies,” explains Dr. Raúl Zamora, principal investigator of IDIBELL-ICO and co-director of the study. “This study is rather a first attempt to leave the laboratory and check at street level if the properties of polyphenols are as we think. Based on the results, we can propose new hypotheses and research to delve deeper into the properties of these compounds.”

Diet, a factor of great variability that is difficult to study

However, diet is a factor of great variability between populations, especially between different geographical areas and countries, as is the case of the EPIC study. For example, evaluating the average daily intake of polyphenols, among all the countries studied, the Danish were the ones who recorded the highest consumption (an average of 1,573 mg/day) while the lowest intake was in Spain (728 mg/d). Within each country and at each time, variability is also important. The danish diet is not the same as that of catalans, but neither is that of a Catalan person with that of an Andalusian or a Galician. Dietary habits are evolving, and the growing trend to increase plant components in the diet could have an impact on health that still needs to be studied.

“We are working on it. In fact, the incidence of some subtypes of lymphoid neoplasms in the Asian population is lower. If it’s a matter of diet, and soy as a major component of your eating habits has anything to do with it, we’ve yet to find out. Studies in Asian populations with a high consumption of soy products will help clarify this relationship,” says Dr. Casabonne.

The Bellvitge Biomedical Research Institute (IDIBELL) is a research centre created in 2004 and specialising in cancer, neuroscience, translational medicine and regenerative medicine. It has a team of more than 1,500 professionals who, from 73 research groups, publish more than 1,400 scientific articles a year. L’IDIBELL is participated by the Bellvitge University Hospital and the Viladecans Hospital of the Catalan Health Institute, the Catalan Institute of Oncology, the University of Barcelona and the City Council of L’Hospitalet de Llobregat.

IDIBELL is a member of the Campus d’Excelencia Internacional of the University of Barcelona HUBc and is part of the CERCA institution of the Generalitat de Catalunya. In 2009 it became one of the first five Spanish research centres accredited as a health research institute by the Carlos III Health Institute. In addition, it is part of the HR Excellence in Research program of the European Union and is a member of EATRIS and REGIC. Since 2018, IDIBELL has been an Accredited Centre of the AECC Scientific Foundation (FCAECC).