"Body Selects Deficient Nutrients Directly"... Mechanism of 'Picky Eating Control' in the Gut-Brain Axis Identified [Reading Science]

The Gut Detects Protein Deficiency and Modulates Brain Neural Circuits
Opens New Possibilities for Treating Obesity, Metabolic Disorders, and Eating Behavior Disorders

A team of Korean researchers has identified the mechanism by which the gut detects nutritional deficiencies in the body and transmits signals to the brain to selectively encourage the intake of specific nutrients—a process known as the "gut-brain axis." This discovery is being hailed as a new clue for future research into the treatment of obesity, metabolic disorders, and eating behavior disorders.

On May 22, the Ministry of Science and ICT announced that a research team led by Sungbae Seo, Head of the Microbiome-Gut-Brain Physiology Research Group at the Institute for Basic Science (IBS), in collaboration with researchers from Seoul National University and Ewha Womans University, had uncovered the operating principle of the gut-brain axis that induces and regulates the brain’s selective feeding behavior.

Schematic diagram illustrating the process by which the CNMa hormone secreted from the intestines transmits protein deficiency signals to the brain through neural and hormonal pathways when essential amino acids are lacking. The gut-brain axis promotes the intake of essential amino acids while suppressing carbohydrate consumption, thereby regulating behavior to prioritize the intake of deficient nutrients. Provided by the research team

The results of this study were published online at 3:00 a.m. (Korean Standard Time) on the same day in Science, one of the world’s most prestigious academic journals.

The research team confirmed that when the gut detects a protein deficiency in the body, it alters neural circuits in the brain through specific neural and hormonal signals, prompting behavior that prioritizes the intake of essential amino acids.

The gut is known not only as a simple digestive organ but also as one that senses food components, nutritional status, and gut microbiota to regulate systemic metabolism. However, the process by which signals originating in the gut are translated into the brain’s "food choice" behaviors had not been clearly elucidated.

Research team discussing data in the laboratory. Video capture provided by IBS

In a previous 2021 Nature paper, the team established that when fruit flies are in a protein-deficient state, the gut secretes a peptide hormone called "CNMa," which leads to a preference for protein-rich food.

This latest study further revealed the pathway by which the CNMa signal is transmitted to the brain and uncovered a new mechanism for the operation of neural circuits.

"Rapid Neural and Slow Hormonal Signals" Function in Parallel

The researchers found that the gut-brain axis is not a single pathway but a sophisticated system that utilizes rapid neural signals and slower hormonal signals simultaneously.

When the gut epithelial cells detect protein deficiency, they first send a rapid signal to the brain via the neural pathway, inducing the consumption of essential amino acids.

Subsequently, the CNMa hormone secreted from the gut travels through the circulatory system to the brain, helping to sustain the preference for protein-rich food.

The study also confirmed that gut-derived CNMa signals not only promote the intake of essential amino acids but also suppress the activity of DH44 neurons, which induce carbohydrate consumption.

Corresponding author Seongbae Seo, head of the IBS Microbiome-Gut-Brain Physiology Research Group, is explaining the research results. Video capture provided by IBS

The researchers explained that this means animals do not simply increase their overall food intake but instead adjust their diet by selectively consuming deficient nutrients while reducing others to maintain dietary balance.

The research team also found that this gut-brain axis system operates not only in fruit flies but also in mammals such as mice.

Notably, the same response was observed even in the absence of the liver-derived hormone "FGF21," previously considered a key hormone in protein deficiency response, suggesting the existence of an independent regulatory system apart from established hormonal mechanisms.

Sungbae Seo, Head of the IBS research group, stated, "Currently, most drugs for obesity and appetite control leverage gut hormone signals, but the effects and pathways of naturally secreted gut hormones on the brain and behavior have not been sufficiently studied. This research elucidates the principle of nutrient selection between the gut and brain and will serve as an important foundation for future studies on treating obesity, metabolic disorders, and eating behavior disorders."

This content was produced with the assistance of AI translation services.