French researchers have uncovered a link between impaired fructose absorption and increased anxiety levels. Excess fructose that the gut fails to absorb can alter the composition of the gut flora, trigger inflammation, and consequently affect brain function. These findings have been published in the journal Brain, Behavior and Immunity (BBI).
Fructose is a type of simple sugar found in fruits and vegetables. It is also added in large quantities to sugary drinks, juices, and processed foods. To absorb this substance, a specific transport protein is required in the small intestine. When the amount of fructose exceeds the capacity of this mechanism, some of the sugar ends up in the large intestine, where it becomes food for bacteria. This condition is known as fructose malabsorption.
The study’s authors aimed to investigate whether this mechanism could influence not only digestion but also mental state. The study involved 55 healthy men who monitored their diets for a week. Afterward, they underwent a breath test to assess how effectively fructose was absorbed by their bodies.
It was discovered that 60% of the participants exhibited symptoms of fructose malabsorption, despite consuming similar amounts of fructose.
Psychological questionnaires revealed that participants with fructose malabsorption reported, on average, higher levels of anxiety. These individuals also showed elevated levels of inflammatory proteins and bacterial toxins in their bloodstream, along with notable differences in their gut microbiota composition.
The researchers conducted further experiments on mice genetically engineered to lack the fructose transporter protein. After four weeks of a fructose-enriched diet, these rodents displayed more pronounced anxious and depression-like behaviors compared to control groups.
In these mice, significant alterations in gut microbiota composition were observed. Furthermore, in microglia, the immune cells of the brain, genes associated with inflammation were activated. This evidence indicates that inflammatory processes originating in the gut can impact the central nervous system.
About the Author
