Recent findings from a pivotal long-term study have revealed concerning health impacts associated with the artificial sweetener aspartame. Conducted by a research team from CIC biomaGUNE and the Biogipuzkoa Health Research Institute in Spain, this year-long research aimed to investigate the effects of aspartame on both brain and heart function in a real-world setting. The study focused on doses significantly below the current Acceptable Daily Intake (ADI) limits, addressing limitations that have affected previous research.
While aspartame is among the most scrutinized food additives globally, earlier studies often involved short durations and high doses that did not reflect typical consumption patterns. The findings of this new study are particularly relevant as regulatory bodies, including the World Health Organization (WHO) and the US Food and Drug Administration (FDA), have deemed aspartame safe when consumed below established thresholds. In 2023, the WHO classified aspartame as “possibly carcinogenic to humans,” underscoring the need for further research.
The experimental design involved administering aspartame at a dosage of 7 mg/kg (approximately 3.17 mg/lb) to a group of eighteen mice over the study period, while a control group of fourteen mice received no dose. Researchers sought to assess the physiological impacts of aspartame on heart and brain function, comparing these effects with those of other sugars and sweeteners.
Key Findings on Brain Function
The study produced significant insights into brain metabolism. Using FDG-PET imaging, researchers observed glucose uptake across various brain regions. After just two months of intermittent aspartame intake, glucose uptake in the brains of the treated mice surged, nearly doubling compared to the control group. However, this initial spike reversed by the six-month mark, with glucose consumption dropping to about 50% less than in the control group.
This reduction in glucose uptake is alarming, as the brain relies heavily on glucose for essential functions, including neuron firing and memory processes. The early increase in energy use shifted to a state of underuse, suggesting a potential metabolic strain rather than adaptation.
To delve deeper, researchers examined metabolites in the cerebral cortex using magnetic resonance spectroscopy. Levels of N-acetylaspartate (NAA), a marker of neuronal health, were initially about 13% higher in the aspartame group. By four months, however, these levels declined, and by eight months, lactate levels had increased significantly—by approximately 2.5 times—indicating cellular dysfunction.
The relationship between astrocytes, which convert glucose to lactate, and neurons is crucial. When lactate accumulates due to persistent high levels, neurons struggle to utilize it effectively, disrupting the energy balance in the brain. This scenario can lead to inefficiencies in neural circuits, potentially hindering cognitive functions such as learning, attention, and complex problem-solving.
In spatial learning and memory tests using the Barnes maze, aspartame-treated mice exhibited slower movement and longer times to locate escape routes compared to controls. While not all results were statistically significant, performance gaps widened over time, with some mice failing to complete tasks altogether.
Impact on Heart Health
The effects of aspartame were not confined to the brain. Cardiac imaging revealed substantial changes in heart structure and function among the treated mice. Their hearts demonstrated less efficient pumping, with chambers not emptying completely and delivering reduced blood volume with each beat. This inefficiency could lead to decreased oxygen delivery to critical organs, including the brain.
Interestingly, while aspartame-treated mice accumulated about 20% less total body fat over the study period, this reduction did not equate to improved metabolic health. Despite similar body weights, fat distribution shifted, with an increase in visceral fat around internal organs and a decrease in lean mass. This repartitioning of fat can exacerbate strain on both heart and metabolic functions.
Researchers concluded that while aspartame may contribute to weight loss in mice, it is accompanied by detrimental changes in cardiac health and cognitive performance. The study emphasizes the necessity for long-term investigations into the chronic effects of aspartame on human health.
Although the results stem from an animal model and require further verification in humans, they underscore the importance of understanding the long-term implications of aspartame consumption. Since its FDA approval in 1974, aspartame has become a staple in many diet foods and beverages, leading to ongoing discussions about its safety and health effects.
The findings of this study were published in the journal Biomedicine & Pharmacotherapy, contributing to the evolving discourse on artificial sweeteners and their potential health risks.
