A study shows that the beneficial effects of polyphenols on obesity may vary due to seasonal changes in gut microbiota

Organisms adapt to changes in the environment, such as light conditions (photoperiod) and temperature, throughout the year. These changes mark what are known as seasonal rhythms, which consist of oscillations throughout the year in various physiological and metabolic processes and/or parameters, such as sleep, mood, body temperature and the release of certain hormones.

For the first time in an animal model of obesity, a study by the URV has shown that the composition of the gut microbiota depends on photoperiod conditions, one of the key features of seasonal rhythms. This is of great importance because this intestinal flora plays a fundamental role in the correct functioning of our organism, and disorders have been associated with such pathologies as metabolic syndrome and obesity. The results of the research by Verónica Arreaza-Gil, Cristina Torres and Anna Arola, researchers from the Department of Biochemistry and Biotechnology, have been published in the journal Food & Function.

It seems, then, that the composition of the gut microbiota can depend on the season of the year, and the differences in composition can make individuals susceptible to some extent or another to developing obesity. More specifically, this study has shown that the rats kept in long photoperiod conditions (with more hours of light and therefore fewer hours of activity since these animals are nocturnal) showed a greater alteration of the gut microbiota, which correlated with greater obesity.

Arreaza-Gil explains that “if we extrapolate this to humans, what we would expect to observe is that the changes in the gut microbiota observed in the period of the year when we have more hours of darkness, and therefore less activity in general terms, are associated with a greater risk of developing metabolic pathologies such as obesity since, unlike rodents, we are diurnal.” However, further study is required to confirm this hypothesis.

Polyphenols and microbiota: how are they affected by the season of the year?

The study also shows that the beneficial effects of polyphenols (chemical compounds in fruits and vegetables) on preventing or alleviating obesity also depend on the photoperiod and, at least in part, the changes in the composition of the gut microbiota. The results reinforce the theory that gut bacteria play a leading role in mediating the effects of bioactive compounds, because they intervene in the metabolism of these polyphenols.

Most of the polyphenols that we ingest in our food reach the colon where they are metabolised by the gut microbiota, giving rise to various phenolic compounds which can have different anti-obesogenic properties. Therefore, changes or alterations in these intestinal bacteria can lead to different phenolic compounds and thus to a change in their functionality.

The study by the Nutrigenomics group and the researcher Verónica Arreaza Gil, under the supervision of Anna Arola Arnal and Cristina Torres Fuentes, shows the importance of chrononutrition, a new and growing field in the treatment and prevention of diseases such as obesity.

Bibliographic reference: Arreaza-Gil V, Escobar-Martínez I, Muguerza B, Aragonès G, Suárez M, Torres-Fuentes C, Arola-Arnal A. The effects of grape seed proanthocyanidins in cafeteria diet-induced obese Fischer 344 rats are influenced by faecal microbiota in a photoperiod dependent manner. Food Funct. 2022 Aug 15;13(16):8363-8374. doi: 10.1039/d2fo01206e.