(RxWiki News) Our tongues are full of taste receptors that tell us if food is good or bad, spoiled or toxic. Now, it appears as though our organs also have taste receptors.
Certain cells - called beta cells - in the pancreas use taste receptors to identify and react to fructose, a kind of sugar. When these cells sense fructose in the body, they release insulin, a hormone that manages blood sugar and plays a large role in diabetes.
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"Before this study, fructose's effect on insulin release was not appreciated," says Björn Tyrberg, Ph.D., an adjunct assistant professor at Sanford-Burnham Medical Research Institute.
"Fructose, and especially high-fructose corn syrup, is found in everything from sodas to cereals, but it remains to be seen whether dietary fructose is good or bad for beta cells and human metabolism," he explains.
Much of the diabetes epidemic in the United States has been blamed on the large amounts of processed foods that we eat. Many of these processed foods have high levels of high-fructose corn syrup.
The study by Dr. Tyrberg and colleagues sheds some light on how this common sweetener may play a role in the development of diabetes.
After you eat, beta cells in your pancreas release insulin in response to higher levels of glucose, another kind of sugar. Insulin then attaches to different cells throughout the body, which allows glucose to enter those cells to be used for energy.
As this study reveals, glucose is not the only sugar that leads beta cells to release insulin. Fructose also may trigger insulin secretion.
"I think the key point to take away from this is that the body sees fructose and glucose as the same when it comes to an insulin response," says Mark Bans, D.C., of Bans Health and Wellness in Austin, Texas, who was not involved in the study.
"I think we've always known this, since one of the first things they want you to give a diabetic who is descending into a dangerously low blood sugar state is orange juice," he says.
"For anyone who is diabetic, wanting to lose weight, or having problems with metabolic syndrome (pre-diabetes), watching fruit or fruit juice intake is just as important as watching sugar intake," says Dr. Bans.
"Whole fruits are better by far than juice. With the whole fruits, you at least get the pulp, fiber, etc. that helps to slow down the absorption process. Juice itself is like drinking several fruits at once - something you would never normally do in real life," he explains.
"There are tools out there on the glycemic index of fruit (how much each causes your blood sugar to increase and how fast). I would encourage everyone who is concerned to research this and make healthy choices on which fruits and the quantity of fruits they eat," Dr. Bans recommends.
By looking at pancreatic cells from humans and mice, Dr. Tyrberg and colleagues found that beta cells respond to fructose in the body using taste receptors that sense sweetness. As levels of both glucose and fructose increase after a meal, beta cells react by releasing more insulin.
In order to test this finding, the researchers looked at cells that were altered to be without the taste receptor gene. With this gene out of the picture, fructose did not trigger beta cells to release insulin.
According to George A. Kyriazis, Ph.D., first author of the study, "These findings are interesting because we know that insulin affects blood glucose levels, indicating that these newly identified beta cell taste receptors might play a role in metabolic diseases such as obesity and diabetes."
This research received funding from the National Institute of Diabetes and Digestive and Kidney Diseases and the American Diabetes Association. The results are published in the Proceedings of the National Academy of Sciences.