How the gut and brain drive sugar preference in animals
What it found
In animal studies, special gut cells detect glucose and send rapid signals to the brain that drive a preference for sugar over artificial sweeteners.
This gut sensing relies on a transporter called SGLT1 rather than sweet taste alone.
What they found
Animal and lab studies
Gut cells detect glucose
Special cells in the upper small intestine of mice, called neuropod cells, use a sensor named SGLT1 to detect glucose. When they sense sugar, these cells release the chemical messenger glutamate within milliseconds. Fructose does not activate this sensor.
Sugar preference without taste
Mice bred without working sweet taste receptors could still tell real sugar from water and preferred it. Blocking the SGLT1 sensor in the gut stopped mice from learning to prefer glucose. This shows the gut, not just the tongue, drives sugar preference in animals.
Vagus nerve carries signals
The glutamate released by gut neuropod cells activates sensory fibres of the vagus nerve in mice. Silencing these specific vagal neurons stopped mice from preferring glucose over an artificial sweetener. The nerve acts as a direct line from the gut to the brainstem.
Brain reward circuits respond
In mice, sugar reaching the gut triggered dopamine release in a brain area called the dorsal striatum. Artificial sweeteners only caused dopamine release in a different area, the ventral striatum. Activating the right vagal nerve branch increased dopamine in the dorsal striatum of mice.
Fructose is weaker
In mouse experiments, fructose was much less effective than glucose or sucrose at driving animals to work for a sugar infusion. Pumping fructose directly into the stomach also failed to teach mice to prefer a paired flavour. Glucose and sucrose strongly conditioned these preferences in rodents.
What the authors conclude
- They propose a model where gut cells sense sugar through SGLT1 and send rapid signals via the vagus nerve to brain reward and feeding circuits.
- Their model suggests that artificial sweeteners fail to improve dietary choices because they do not trigger this gut-based signalling pathway.
- The authors suggest that understanding this full sensory system could help future efforts to address dietary imbalances.
How it was done
The authors note that using non-nutritive sweeteners to target taste alone has not reduced obesity or metabolic disease. They wanted to understand how animals detect, tell apart, and choose to consume sugar beyond just tasting it.
The authors gathered and examined published research on how the gut senses sugar and signals the brain. The work they reviewed involved mice and rats studied across many decades of experiments. They focused on molecular sensors, gut cells, nerve pathways, and brain circuits.
What it can’t tell you
- All the findings come from mice and rats, so they cannot show exactly how human brains and guts handle sugar.
- These animal studies used controlled infusions and genetic tools that do not reflect how people eat mixed meals.
- Scientists do not yet know if blocking these gut signals would change sugar intake in people.
Who paid
- Funding
- Funded by NIMH NIH HHS; NIDDK NIH HHS; NCCIH NIH HHS; NIGMS NIH HHS (from the PubMed record).
- Authors work at
- Duke University, USA
The paper
- Title
- The neural basis of sugar preference
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Liu WW, Bohórquez DV (2022). The neural basis of sugar preference. Nature reviews. Neuroscience. doi:10.1038/s41583-022-00613-5Free full textPubMed 35879409DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error