NOV 06, 2022 3:54 PM PST

How a High-Sugar Diet Can Weaken the Perception of Sweetness

WRITTEN BY: Carmen Leitch

Added sugars are in so many food products, they are difficult to avoid even when you're trying, and high sugar diets have become the norm in much of the Western world. Researchers have wondered whether all that sugar was affecting people's perception of taste. Using a rat model, they determined that high sugar diets can dull the taste system's ability to sense sweet flavors, confirming previous studies. But this research showed why the nerve that sends information about sweetness from the tongue to the brain was 50 percent less responsive in rats that were fed a high-sugar diet. The findings have been reported in Current Biology.

Previous work has shown that if sugar intake is reduced, people's perception of sugar will become more intense. Researcher Monica Dus, an associate professor of molecular, cellular and developmental biology at the University of Michigan, wanted to know how that was happening.

“Several of our previous papers found that sugar dulls sweet taste in fruit flies by lowering the responsiveness of the nerve and reprogramming the taste cells, but flies are still just flies. I really wanted to understand if and how it was happening in mammals," said Dus.

Dus and collaborators used two groups of rodents, one fed a normal diet and plain water, while another got the regular diet and sugar water. Four weeks later, the researchers measured nerve responsiveness when the rat tongues were exposed to various stimuli, including bitter, salty, sour, umami, and sweet flavors. They focused on the nerve that carries information about taste from the front of the rat tongue to the brain. The rats' responses to temperature were also measured.

This work showed that there was no change in the perception of bitter, salty, sour, or umami flavors, and no change in how they perceived hot or cold temperatures. However, the response to sweet flavors was reduced by 50 percent in the rats that received sugar water.

“This is not a subtle effect. It is really strong, and it only took four weeks,” Dus noted.

There was no weight gain from the increased sugar intake.

The rats were all put back on a normal diet, and after another four weeks, the researchers repeated the sensitivity test to sweetness. They found that it had returned to normal. That could be good news for people, said Dus, because it may be reversible if people experience the same phenomenon. The taste system is known to be flexible, or plastic, and the researchers weren't surprised by their findings.

Further work showed that there had been no change in the structures that house taste buds on rat tongues, there was not a reduction in the number of taste buds, and the nerve that links up with taste buds was not altered. However, there were fewer cells that detect sweet flavors in the rats that had been exposed to a high-sugar diet, potentially explaining why the perception of sweetness is impacted so significantly.

Image credit: Pixabay

The researchers now want to know more about how changes in the perception of sweetness might change human behavior. In flies, for example, a reduced sensation of sweetness causes a reduction in dopamine release, and leads to overeating because satiety is impaired.

Human and rats have similar mechanisms of taste perception, so this the best evidence we have now that shows that high sugar diets can alter sensory systems. It may be influencing how people eat, or their metabolism. But, the system also seems to be malleable, and we may be able to change foods so they don't contain so much sugar, said Dus. We may even enjoy those less sugary foods just as much if we aren't overloaded with the stuff.

Sources: University of Michigan, Current Biology

About the Author
BS
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
OCT 06, 2022
Microbiology
A Microbial Predator Can Wreak Havoc in the Desert
OCT 06, 2022
A Microbial Predator Can Wreak Havoc in the Desert
The microorganisms of the world are in constant conflict, battling for resources and space in a microbial arms race. Som ...
OCT 18, 2022
Clinical & Molecular DX
New Mitochondrial Disease Identified in Identical Twins
OCT 18, 2022
New Mitochondrial Disease Identified in Identical Twins
A new mitochondrial disease has been identified after a pair of identical twins were showing an unusual symptom. Despite ...
OCT 21, 2022
Drug Discovery & Development
Gel-encased Radioactive Iodine Eliminates Pancreatic Cancer in Mice
OCT 21, 2022
Gel-encased Radioactive Iodine Eliminates Pancreatic Cancer in Mice
Researchers have developed a radioactive gel that eliminated pancreatic tumors in 80% of mice. The corresponding study w ...
OCT 30, 2022
Neuroscience
Why Fear Memories Can Persist in the Brain
OCT 30, 2022
Why Fear Memories Can Persist in the Brain
People have to experience fear so they can learn to avoid dangerous situations. But some memories can be more persistent ...
OCT 31, 2022
Genetics & Genomics
Ancient Viral DNA in Our Genome Has a Protective Function
OCT 31, 2022
Ancient Viral DNA in Our Genome Has a Protective Function
There is viral DNA in the human genome, and each instance traces back to an ancestor who was infected with a retrovirus. ...
NOV 02, 2022
Microbiology
RSV & Influenza Can Combine to Form a New, Hybrid Virus
NOV 02, 2022
RSV & Influenza Can Combine to Form a New, Hybrid Virus
While different strains of influenza virus can co-infect cells and form hybrid flus, virus co-infections have tended to ...
Loading Comments...