A study led by a Spanish institute has uncovered the relationship between gut microbiota and attention span in people with obesity.
Obesity is associated with poorer care, but now this study, published in the journal Gut and led by the Josep Trueta Institute for Biomedical Research of Girona (IDIBGI), is the first to look at the role of the gut microbiota in that connection.
Microbiota affects people with obesity
The great importance of the gut-brain axis 🧠
The gut microbiota modulates the HPA (stress ↔ cortisol) axis and with it key processes such as memory, learning and emotions.
🔹When there is dysbiosis or chronic stress, the axis is altered: inflammation increases, the… pic.twitter.com/bU5FOKOHvd– Spanish Society of Digestive Pathology (SEPD) (@sepdigestiva) October 14, 2025
Specifically, it links a higher level of proteobacteria in the gut microbiota to poorer attention span in people with obesity, while another compound in the microbiota (3-HAA) is associated with improved attention.
The microbiota interacts with the organism and exerts a large number of functions; it is estimated that there are between 20 and 100 times more microbial genes than human genes in the body.
Therefore, beyond looking at “what” microorganisms there are, it is very important to analyze “what they do, their genetic material and the substances they produce or modulate in the organism, according to one of the researchers who led the study, Dr. Jordi Mayneris-Perxachs, from IDIBGI.
Researchers have focused on identifying which specific components of the gut microbiota are associated with greater or lesser attention span by analyzing stool and blood samples from three groups totaling more than 1,000 people.
“To integrate all this data we have applied advanced computational techniques based on machine learning – also known as ‘machine learning’ – that allow us to examine previously unattainable amounts of information and obtain deeper and more valuable knowledge,” explains Mayneris-Perxachs.
A first analysis of two cohorts showed that people with obesity and lower attention span had a microbiota with increased proteobacteria and alterations in the metabolism of tryptophan, an essential amino acid for health that is obtained through the diet and processed with the participation of the intestinal microbiota.
This finding led to further investigation of the role of tryptophan metabolism: the researchers observed that higher levels of a derivative compound, called 3-HAA (3-hydroxyanthranilic acid), were associated with better attention, while other compounds showed the opposite effect.
To test whether this relationship could be causal, they tested with a university, Pompeu Fabra, and transplanted microbiota from humans into mice.
Thus, they observed that animals that received microbiota from donors with better attention showed signs compatible with better cognitive flexibility and attention capacity.
In another model, fruit fly, an obesity-inducing sugar-rich diet, or also the presence of a particular proteobacterium species (Enterobacter cloacae), impaired attention-related behaviors, whereas 3-HAA supplementation improved them.
With information from EFE
Filed under: Microbiota obesity
