byCIC biomaGUNE

The team observes magnetic resonance images of a mouse's heart. From left to right: Sandra Plaza García, Irati Aiestaran Zelaia, Irene Fernández Folgueral and Marta Beraza. Credit: CIC biomaGUNE

A study by CIC biomaGUNE and Biogipuzkoa HRI conducted on mice has found that the prolonged intake of sweeteners may exert harmful effects on the function of various organs. Artificial sweeteners are widely used to reduce the intake of sugar and control body weight.

The paper ispublishedin the journalBiomedicine & Pharmacotherapy.

Although these substances were initially thought to be beneficial to health, in recent years there has been growing concern that they may have adverse effects on the metabolism of cells and organs in the long term.

One of the most ubiquitous sweeteners, aspartame, is widely used in sweets, diet soft drinks, bakery products, chewing gum, etc. It produces a sweet taste 200 times greater than sucrose, so its caloric value is relatively low. Numerous studies have explored the effects of aspartame; however, until now, its long-term metabolic and behavioral effects have not been known.

A study conducted by the researcher Irati Aiestaran-Zelaia, supervised by the Ikerbasque Research Professors Jesús Ruiz-Cabello of CIC biomaGUNE and Ian J. Holt of Biogipuzkoa HRI, has assessed the effects of long-term aspartame consumption in mice, by exposing them for one year to a dose equivalent to one-sixth of the maximum recommended daily intake for humans.

The study concluded that "aspartame does indeed reduce fat deposits (by 20%) in mice, but it does so at the cost ofmild cardiac hypertrophyand decreased cognitive performance," the research team confirmed. These findings indicate that "although this sweetener may help achieve weight loss in mice, it is accompanied by pathophysiological changes in the heart and, possibly, in the brain," they added.

The daily dose of aspartame used in the study was 7 mg per kg of body weight in human equivalent units. "This dose is well below the maximum dose recommended by the World Health Organization, the EMA (European Medicines Agency) and the FDA (Food and Drug Administration, U.S.), which is 50 mg/kg per day. This highlights the importance of the results obtained in the study," they pointed out.

The study demonstrates thatprolonged exposure to artificial sweetenersmay have a detrimental impact on organ function, even at low doses, suggesting that current consumption guidelines need to be critically reviewed.

This study, which examined for the first time the effects of aspartame intake over a full year, helps to fill significant gaps in knowledge about the consequences of long-term consumption, and provides crucial information on the chronic effects resulting from intake levels achievable through a normal diet.

In fact, as the CIC biomaGUNE and Biogipuzkoa HRI researchers pointed out in the study, "we observed effects that have not been described until now, most likely due to the difficulty and duration of the study."

It should be noted that these results are supported by "a large quantity of data of all kinds: functional imaging (magnetic resonance imaging), molecular imaging (positron emission tomography), brain and liver spectroscopy, cognitive tests, temperature, amount of food and drink, etc. They have helped to explain the effects aspartame has on mice and will serve as a basis for reinforcing and expanding the conclusions of this study."

The study is part of a series of studies in which "we are observing how nutrient modulation impacts organ function in sickness and in health, and in this case, we set out to determine the physiological impacts aspartame exerts on the hearts and brains of mice, as well as its effect on fat levels and body weight, in order to compare them with other types of sugars and sweeteners," they conclude.

More information Irati Aiestaran-Zelaia et al, Aspartame decreases fat deposits in mice at a cost of mild cardiac hypertrophy and reduced cognitive performance, Biomedicine & Pharmacotherapy (2026). DOI: 10.1016/j.biopha.2025.118891 Journal information: Biomedicine & Pharmacotherapy

Provided by CIC biomaGUNE