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Our digestion stimulates bitter substances in coffee can regulate gastric acid production
Many people opt for a coffee or a bittersweet after a long meal. Such drinks should eventually help to stimulate digestion. Many doubt, however, that this really helps. Researchers have now found out that the bitter substance caffeine can have an effect on gastric acid production and thus also on digestion.
Folk wisdom about digestion
Some people try to stimulate digestion with a cigarette after eating. Others say, especially schnapps help here. It is also common to drink an espresso or other coffee after a meal. According to experts, many popular beliefs about digestion are wrong. An international research team has now found that caffeine can have an effect on gastric acid production.
Many people have a coffee after eating. Researchers have now shown that the bitter substance caffeine can regulate gastric acid production and thus have an effect on digestion. (Image: Rawpixel.com/fotolia.com) Caffeine can regulate gastric acid release
The stimulating bitterness caffeine can both stimulate and delay the release of hydrochloric acid in the stomach, depending on whether it activates bitter receptors in the stomach or in the mouth.
"As our results show, bitter receptors generally play a role in the regulation of gastric acid secretion. It would therefore be conceivable that bitter substances or bitter blockers could be used in the future as therapeutics to treat hyperacidity of the stomach, "explained study leader Veronika Somoza from the University of Vienna in a statement.
The team led by food physiologist Somoza and first author Kathrin Liszt from the Faculty of Chemistry at the University of Vienna, which includes researchers from the German Institute for Human Nutrition (DIfE), Jakob Ley from Symrise AG in Holzminden and scientists from the Blizard Institute London his results now in the journal "PNAS".
What was known at baseline
Caffeine not only stimulates the central nervous system and increases blood pressure, it also stimulates the release of stomach acid.
Recent studies also indicate that in addition to caffeine, other bitter substances, such as hops, stimulate acid production in the stomach. But what mechanisms do this is not yet adequately researched.
It is also known that humans perceive bitter substances through about 25 different bitter receptor types, which are located in the mouth and throat on the tips of the taste receptor cells and should warn against ingestion of toxic substances.
Five of them react to caffeine, among other things. More recently, studies have begun to show that bitterness taste receptors are also found elsewhere in the digestive system, such as the stomach. The function of the receptors there is largely unknown and also poorly understood.
Half an hour after caffeine intake increased gastric acid secretion
Since the existing facts suggest that caffeine influences the gastric acid secretion via bitter receptors in the mouth and stomach, the scientists in the current study investigated the question of whether such a connection actually exists.
For this purpose, pH measurements in the stomach were carried out in healthy female and male study participants.
In addition, the researchers used human tissue samples of the stomach and an established cellular model system (HGT-1 cells) for the study of gastric acid release, to be able to check the relationship at the cellular and molecular level.
When study participants took 150 mg of caffeine encapsulated in the form of a pill, which dissolved in the stomach, this led to increased secretion of stomach acid after about 30 minutes.
On the other hand, if the participants received a suitable caffeine solution that stimulated not only the receptors in the stomach but also the bitter receptors in the oral cavity, the gastric acid secretion was delayed.
The perceived bitterness of caffeine correlated with the amount of gastric acid secreted. In addition, in both human gastric and HGT-1 cells, the researchers detected bitter receptors that respond to caffeine.
On the model system of HGT-1 cells, they also showed that the bitter receptor TAS2R43 is at least one of the receptors through which caffeine regulates gastric acid secretion. Switching off the TAS2R43 receptor at the gene level (knock out model) additionally confirmed this result.
The stimulating effect could be reduced by the addition of homoeriodictyol, a bitter blocker that also inhibits TAS2R43. Subsequently, tests performed with study participants, in which the subjects took the bitter blocker together with caffeine, also led to a reduction in caffeine effects.
Conclusion and outlook
"Although a glass of bitters or coffee is common in post-meal cultures to address digestive problems, we still know amazingly little about the molecular interaction of bittering agents and the digestive system," said Veronika Somoza of the Institute of Nutritional Physiology and Physiological Chemistry the University of Vienna.
"To clarify these correlations could in the future contribute to the development of new therapeutics for the treatment of reflux disease or gastric ulcers," the professor continues.
"In any case, our results are promising and prove that bitter receptors are involved beyond their function as taste sensors in the regulation of digestive processes," added co-author Wolfgang Meyerhof from DIfE.
"The research on bitter receptors, which we have already detected in the intestine, myocardial and thyroid cells, not only reveals completely new perspectives and starting points in this connection, which we want to pursue in the future with our cooperation partners," says DIfE. Taste researcher Maik Behrens concluding. (Ad)