A high sugar diet dulls sweet taste. In a rat study, a long-term high-sugar diet cut the sweetness signal from tongue to brain by about half compared with a low-sugar diet. That may push eating habits toward more sugar and metabolic disease. Cutting back on sugar restored the sense of sweetness.
Summary: Eating too much sugar may dull the sense of sweetness. A new study fed rats a high-sugar diet for a long time. When given sugary syrup, their tongue-to-brain signal was 50% weaker than in rats on a low-sugar diet. These changes in taste buds may play a role in metabolic disorders. The good news: when the high-sugar diet stopped, the animals could taste sweetness again.
Sugar is sweet and addictive. It is made by processing plants like beetroot or sugarcane. People who eat a lot of sugar are also more likely to complain that something is not as sweet as it should be.
Once people eat more sugar regularly, they need even more to satisfy their sweet tooth. It is as if they no longer sense the sweetness. Their sense of sweetness has gone dull.
But those were all just observations. It was unclear whether the cause was in the mind or in the body. What if something more complex was going on, with changes in the brain? Researchers set out to test the idea.
In the new study, researchers worked with lab rats. They fed them a high-sugar diet and measured the nerve signals from the tongue to the brain. To their surprise, these signals dulled over time. Their strength dropped by almost 50%, a huge difference. The results were published in the journal called Current Biology.
Researchers say this is not the first finding of its kind. Earlier they found that sugar dulls sweet taste in fruit flies over time. But flies are very different from humans. So not much could be concluded from that study. So researchers tested the idea in mammals like lab rats, which are much closer to humans in how their bodies work.
In the study, researchers split rats into two groups. One group ate a typical diet. The other ate a high-sugar diet. After four weeks, rats from both groups got sugar solutions of different strengths. Then researchers measured the nerve signals from tongue to brain. Rats on the high-sugar diet had a much duller response. Clearly, long-term sugar eating changed the taste buds in these rats.
To learn more, they gave the rats bitter, sour, salty and umami (savory) solutions. The rats’ sense of these other flavors did not change. The change showed up only with the sweet sucrose (table sugar) solution.
There were other interesting findings. Researchers moved the rats on the high-sugar diet back to a normal diet with plain water. Then they tested them again with sugary solutions. To their surprise, the rats’ sense of sweetness had come back.
These findings are encouraging in many ways. Eating a lot of sugar for a long time may dull your sense of sweetness. But the change can be undone. Switching to a low-sugar diet can help bring your sense of taste back. That is good news.
Researchers say the results matched what they expected. Taste is very flexible and can shift easily. So even if taste changes, it can come back.
Under the microscope, researchers saw no significant changes in taste buds or nerves from high sugar. But long-term high sugar did cut the number of sweetness receptors on the tongue. These changes could be undone.
Researchers now want to dig deeper. For example, they want to learn how the changed sweetness signal alters the brain’s activity and its response to foods. They also want to know how it affects appetite and metabolism.
Studies show that sugar is addictive and causes dopamine release. So a duller sense of sugar may mean less dopamine release. That may raise the urge to eat more, leading to obesity. These changes in taste may have a much wider effect on food choices and metabolism.
Frequently asked questions
Why is sugar so addictive?
Studies show that sugar is addictive and causes dopamine release. People who eat more sugar regularly need even more of it to satisfy their sweet tooth. In the rat study described here, a high-sugar diet cut the sweetness signal from the tongue to the brain by almost 50%. A weaker sweet taste may mean less dopamine release. That may raise the urge to eat more and lead to obesity.
Does eating too much sugar change your taste buds?
In the study, rats fed a high-sugar diet for four weeks had a much duller nerve response to sugar solutions than rats on a typical diet. Under the microscope, their taste buds and nerves showed no significant changes. But they had fewer sweetness receptors on the tongue. Their sense of bitter, sour, salty and umami flavors did not change. Only sweetness did.
Can your sense of sweetness come back after cutting sugar?
Yes. When the rats on the high-sugar diet went back to a normal diet with plain water, their sense of sweetness came back. Taste is very flexible and can shift easily, so these changes can be undone. That means switching to a low-sugar diet can help bring back your ability to sense sweetness.
Related reading
How Diet Affects Mental Health · Opioid and Endocannabinoid Systems in Eating Disorders · Drug Addiction Treatment, St. Louis
Sources
- Sung H, Vesela I, Driks H, et al. High-sucrose diet exposure is associated with selective and reversible alterations in the rat peripheral taste system. Curr Biol. 2022;32(19):4103-4113.e4. PMID 35977546 · DOI 10.1016/j.cub.2022.07.063.