Researchers at the University of California, San Francisco, have identified a slow-acting dopamine pathway that may help explain how people develop preferences for foods and drinks such as coffee. In experiments involving mice, along with analyses of human brain-imaging data, the scientists found that nutrients detected in the gut can trigger dopamine activity in brain regions involved in learning whether a flavor is associated with calories and reward. The findings were published online in Nature on November 4, 2026.
A slower dopamine signal
“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.”
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 last 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 produced 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 could not learn that a new taste was associated with calories. After the mice were exposed to a calorie-free flavor, artificially stimulating the same dopamine fibers caused them to develop a preference for it.
“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 brain scans
The researchers also reanalyzed an earlier positron emission tomography study involving 13 men and conducted a new functional magnetic resonance imaging study involving 38 adults. Both analyses found nutrient-related activity in the same brain regions identified in the mouse experiments.
In both mice and humans, the response was stronger on the left side of the brain, although this asymmetry surprised the authors.
Possible implications for food preferences
The findings suggest that food preferences could eventually be adjusted by targeting the learning processes that connect flavors with nutrients and reward.
“One interesting question concerns GLP-1 drugs. These drugs mimic hormones produced in the gut and can dramatically alter eating behavior,” the researchers said.
“We have not studied GLP-1 drugs and it is unclear whether they affect the newly identified pathways.”
“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