Summary: It appears that consuming too much sugar may reduce the sense of sweetness. A new study found that if rats were fed a high-sugar diet for long, it resulted in a 50% decline in signal sent from tongue to brain on exposing them to sugary syrup, compared to rats on a low-sugar diet. These changes in taste buds due to a high-sugar diet may play a role in the development of metabolic disorders. Fortunately, the study also found that on discontinuing a high-sugar diet, the ability of lab animals to experience sweetness was restored.
Sugar is sweet, addictive, and created by processing natural extracts like those of beetroot or sugarcane. People who consume much sugar are also more likely to complain that something is not as sweet as it should be.
Once people start eating more sugar regularly, they need to consume even more sugar to satisfy their sweet tooth. It appears as if they have stopped sensing the sweetness, and their sense of feeling the sweetness has become blunted.
However, those were all observations, and it is unclear whether it is psychological or physiological. What if something more complex is happening, causing some changes in the brain? Researchers decided to test their hypothesis.
In the new study, researchers experimented with lab rats. They fed them a high-sugar diet and measured the nerve signals traveling from the tongue to the brain. To their amazement, they found that these signals became blunted over time, and intensity of these signals was reduced by almost 50%, which is a massive difference. The findings of the study were published in the journal called Current Biology.
Researchers say that this is not the first finding of its kind. Earlier they found that sugar dulls the sweet taste in fruit flies over time. However, flies differ significantly from humans; thus, not much can be concluded from such a study. Therefore, researchers decided to test their hypothesis in mammals like lab rats, as they are physiologically much closer to humans.
In the study, researchers divided rats into two groups. One group was fed a typical diet, and another with a high-sugar diet. After four weeks, they exposed rats from both groups to sugar solutions of different strengths, and then they measured nerve signals traveling from the tongue to the brain in these rats. They found that those fed with a high-sugar diet had a much-blunted response. It is clear that prolonged sugar consumption led to changes in taste buds in these mice.
They gave the rats bitter, sour, salty, and umami-flavored solutions to further understand the phenomenon. They found that their sense of other flavors was unchanged. The changes only occurred towards the sweet sucrose (table sugar) solution.
There were some other interesting findings. Researchers then put the rats on the high-sugar diet back on a usual diet with plain water. They again tested the response of these rats to sugary solutions. To their amazement, they found that their sense of sweetness was restored.
These findings are encouraging in many ways. Though they show that consuming high amounts of sugar for long may blunt your ability to sense sweetness, but these changes are reversible. It means that switching to a low-sugar diet can help restore your senses. This is potentially good news.
Researchers say that the findings were what they expected, as they know that taste sensation is quite plastic and can be readily modulated. Therefore, even if some changes occur in taste, it is possible to restore sensation.
On microscopic examination, researchers found no significant changes due to high sugar consumption in taste buds or nerves. However, they found that consuming high sugar for long reduced sweetness receptors on the tongue, though these changes were reversible.
Researchers say that they are now interested in further investigating the subject. For example, they want to understand how these changes in the sweetness signal to the brain alter its activity and response to various foods and how it affects appetite and metabolism.
Studies show that sugar is addictive and causes dopamine release. It means that low sugar sensation may cause lower dopamine release, which may increase an urge to eat more food leading to obesity. These changes in sensation may have a much broader impact on food choices and metabolism.
