Few people enjoy their first sip of coffee, yet millions eventually crave it. Researchers at the University of California, San Francisco, say they have identified part of the biological mechanism behind this shift: a slow dopamine signal that travels from the gut to the brain and helps people learn to prefer foods associated with rewarding nutrients. The findings were published online in Nature on November 4, 2026.
Researchers identified dopamine pathways that allow the brain to learn about the nutritional content of food. Image credit: Sci.News.
“Dopamine has been intensely studied because it tells us what is worth pursuing and helps guide our behavior. Scientists know a lot about dopamine’s fast-acting pathways,” said the study’s lead author, Professor Zachary Knight of the University of California, San Francisco.
“But the slow side of dopamine is much more mysterious, and we are less conscious of it in our daily lives.”
How nutrients influence the brain
Sensors in the digestive system detect nutrients such as sugar and fat and send signals to the brain. The resulting dopamine signal increases after food reaches the intestine and can continue for many minutes.
In experiments on mice, the researchers bypassed taste by pumping liquids such as sugar water or milkshakes directly into the animals’ stomachs.
The nutrients triggered a sustained release of dopamine in a brain region called the basolateral amygdala. When the scientists blocked this signal, the mice continued to eat normally, but they could not learn that a new taste was associated with calories.
After the mice tasted the calorie-free substance, artificially stimulating the same dopamine fibers caused them to prefer that taste.
“We’ve shown that this slow dopamine system is what drives us to like certain foods over time, and we can see where and how that happens,” Professor Knight said.
“When your brain associates the flavor of your favorite coffee with the high from caffeine, coffee tastes much better.”
Evidence from human studies
A reanalysis of an earlier PET study involving 13 men and a new fMRI study involving 38 adults found nutrient-related activity in the same brain regions.
In both mice and humans, the response was stronger on the left side of the brain. The asymmetry surprised the researchers, however, and its significance remains unclear.
Possible implications for food preferences
The findings suggest that food preferences might eventually be adjusted. The researchers noted that GLP-1 drugs are one area of interest. These medications mimic hormones produced in the gut and can dramatically alter eating behavior.
“We have not studied GLP-1 drugs and it is unclear whether they affect the newly identified pathways,” the researchers said.
“These drugs can potentially reduce dopamine signaling triggered by nutrients, making food less reinforcing over time.”
“It opens up broader possibilities. Beyond just influencing hunger and satiety, future treatments could one day influence the underlying learning processes that make certain foods particularly desirable.”
“By understanding the steps from nutrient detection in the gut to learning in the brain, it may be possible to fine-tune them to subtly change our preferences for different foods.”
Neural basis of flavor and nutrient learning. Nature, published online November 4, 2026. doi: 10.1038/s41586-026-11229-5.
Source: www.sci.news
