UC scientists conclude that the frequent intake of blueberries has a strong impact on the liver

^{Translation by Diana Taborda}

A multidisciplinary team of scientists from the University of Coimbra (UC) has found that continuous consumption of blueberries, at a daily dose of around 240 grams, has a strong impact on the liver, providing important clues for establishing guidelines for healthy and safe consumption of these berries rich in antioxidants.

The discovery, which has already been published in the journal Pharmaceutics, was made during a study aimed at evaluating the possible beneficial effects of blueberry juice in the context of pre-diabetes in an animal model.

Given the rich phytochemical composition of the blueberry, with a variety of bioactive ingredients "that seem to be able to offer numerous protective effects in different conditions, it seemed very relevant to us to also understand the effects of continuous consumption of this "superfood" in a healthy state", explain the study coordinators, Flávio Reis and Sofia Viana, from the Institute of Clinical and Biomedical Research of Coimbra (iCBR) of the Faculty of Medicine of the University of Coimbra (FMUC).

The researchers evaluated a series of metabolic parameters, with a focus on the liver and, in particular, mitochondrial functions, in adult mice that had consumed natural blueberry juice on a regular basis for 14 weeks (equivalent to a human drinking one and a half glasses of juice a day).

At the end of the experiment, when the results were analysed at the level of the liver mitochondria - the energy home of the cell - it was observed that in pre-diabetic mice "there was protection against liver steatosis (accumulation of fat in the liver) and a huge impact at the level of the mitochondria," says Sara Nunes, a PhD student involved in the project. In the case of healthy mice, she points out, "we found that the consumption of blueberry juice had no effect on the metabolic profile and there were no changes at the intestinal level. However, the effect on the liver was surprising, particularly on mitochondrial function, similar to the effect of a high-calorie diet".

The results observed in healthy mice suggest that continuous consumption of blueberries forces a metabolic reprogramming, the consequences of which (beneficial or harmful) remain unclear. The team believes that "the strong effect on the liver generated by the long-term consumption of blueberries may make it possible to prevent or alleviate diseases such as diabetes and obesity, but we cannot rule out the possibility that it may cause some kind of imbalance and have harmful health consequences".

Therefore, the next step of the study will focus on clarifying both hypotheses in order to contribute to the safe consumption of blueberries, "in order to better clarify whether this adaptive response resulting from prolonged blueberry consumption is beneficial or whether, on the contrary, it may be associated with harmful effects. In the context of the current habits of part of the population, this research is particularly relevant," point out Flávio Reis and Sofia Viana.

The health benefits of blueberries are closely linked to their antioxidant activity, "mainly due to their high content of phenolic compounds. Their recognised antioxidant and anti-inflammatory properties are to some extent responsible for the increase in their consumption in recent years," the researchers point out, while noting that "some studies have warned against the possible adverse effects of uncontrolled and excessive consumption of certain antioxidant products, including those enriched with phenolic compounds".

This study is part of a wider research project, in partnership with the Agricultural Cooperative of Farmers of Mangualde (COAPE) and MIRTILUSA (Sever do Vouga), focusing on the therapeutic potential of the blueberry plant as a whole, i.e, In addition to studying the berries (peel and pulp), the team led by Flávio Reis and Sofia Viana is investigating the potential of the leaves, particularly the deciduous leaves, to add value to a part of the blueberry bush that is currently wasted and that cumulatively contains a much greater quantity of bioactive compounds than the fruit.

In this context, the researchers have already developed a technology for processing the leaves, which goes beyond traditional infusions, and the biomass obtained is "very promising, with very strong antioxidant properties from a therapeutic point of view", conclude Flávio Reis and Sofia Viana.