Scientists say they have figured out why bitter herbs show up in folk remedies as a digestive aid, and they tell us which ones actually work.
For centuries humans have used bitter herbs to aid digestion, but until recently it has been a mystery as to whether the effect was real and what it was about bitter tastes that helped. Now, a team of scientists led by Phil Richter and principal investigator Veronika Somoza, say that they have an answer and it’s a little surprising.
In a March 2026 research paper published in Molecular Nutrition & Food Research, University of Munich food scientists report that some common bitter tasting herbs can directly stimulate the cells in your stomach to make more acid.
The researchers describe in their paper how they determined that a variety of herbs used in folk remedies, especially those from master wort, juniper, sage and yarrow, directly interact with cells in the stomach to encourage acid production. Other popular bitter herbs, such as dandelions and gentian, have no measurable effects.
Bitter Truths
People commonly believe that tasting a bitter compound might trigger your stomach to make more acid. Often they invoke the vagus nerve being jolted into action when the shock of the bitter taste hits your tongue. Experiencing the bitterness of the medicine is what makes it effective, we are often told. This is why we are ecouraged to use bitter herbs as a digestive aid.
It turns out, however, that this unpleasant experience isn’t necessary at all. Not only that, it seems, not all bitter herbs prompt an increase in acid production. While sage and juniper trigger gastric cells to produce acid, dandelion and gentian had no measurable effects.
Taste Receptors In our Brains?
Scientists have identified over 25 different bitter tastes detecting receptors in our mouths, but did you know they turn up in other parts of our body? Researchers have found some of these same chemical receptors in our brain, in our hearts, in the lining of our digestive system and even on our blood cells. What are they doing? We still don’t know exactly, and academics are working hard to figure it out.
The receptors could be there to use the polyphenols that produce the bitter flavour as DNA protecting antioxidants, or they might be being recycled by our bodies for a completely distinct purpose. One of the amazing things about our genome is that it turns out we only make around 20,000 proteins, so a bunch of them are repurposed to do different jobs in different contexts. Since there are bitter taste receptors on the cells of our gastric lining, Somaza and Richter wondered what the cells would do if they provoked them with bitter chemicals extracted from herbs.
Somoza and her trainees have now confirmed that the bitter taste receptors found in the stomach can trigger acid production in response to detecting bitter herbs. So in the mouth, these receptors are used to send a message to the brain that the taste is bitter. In the stomach, these same proteins on the cell surface tell our tummy to make more acid when they are activated.
Taste Testers
The team wanted to figure out what was going on in popular herbal digestion remedies. Did they really work? Were they acting directly on the stomach? Which ingredients were responsible for any effects and what were they doing.
They started off by analysing the herbal mixes to find out what’s in them. The most trusted remedies tended to contain some combination of the same nine herbs: common wormwood, common sage, common yarrow, common centaury, common chicory, great yellow gentian, common juniper, masterwork and common dandelion.
They made an educated guess that compounds, known as polyphenols, were the most likely ingredients to be responsible for triggering the receptors in our stomachs. These are extracted in factories and widely sold commercially in supplements and herbal remedies. The team bought extracts of A. absinthium, A. millefolium, C. erythraea, C. intybus, G. lutea, J. communis, P. ostruthium, S. officinalis and T. officinale.
Were these compounds responsible for both the bitter taste and acid production? Would specifically bitter compounds trigger cells in the stomach to do something?
Then they gathered some volunteers and checked whether the compounds they were about to test really were bitter. The unfortunate participants were asked to taste a mixture of all nine compounds mixed together and rate its bitterness compared to the alcohol carrier it was dissolved in. The 19 volunteers swirled the mix in the mouths and spat it out before giving a subjective numerical rating. On average the mix got a moderate to strong bitterness rating.
Test Tube Tummy
Next, the researchers decided to compare extracts from each of these plants alone and in combination to see if they had any effects directly on the acid-making cells of the stomach lining–parietal cells.
Then they added solutions containing combinations of these extracts to acid-making stomach cell samples cultivated in dishes. The team found that adding some of these extracts led to a change in pH of the liquid media in which the stomach cells live. The media became more acidic as the parietal cells pumped out more hydrogen ions. Master wort, juniper, sage and yarrow elected the strongest effects. Chicory, wormwood and centaury encouraged acid production but not dramatically, while dandelion and gentian extracts did nothing. Interestingly, the biggest effect occurred when the researchers mixed all the herbal extracts together.
Turning the Tables
They also looked at how the bitter compound affected the taste receptors themselves. The team found that when they added the mixture of all nine compounds to the gastric cells in a dish, the cells turned off the genes that make the receptors. Testing RNA levels, the team showed that the cells were turning down the production of the TAS2R4, TAS2R5, and TAS2R39 bitter taste receptors by as much as 40%.
Since the cells were tinkering with the levels of these receptors when they were stimulated by the bitter compounds, the researchers tried to figure out which of the receptors reacted to which particular herbs. The team used a combination of cells with gene deletions and a special tool called Short Interfering RNA or SiRNA to silence combinations of the three receptors so that they could investigate which herbal extracts stimulated which receptor.
They discovered that all nine extracts mixed together can trigger all three receptors, but A. millefolium, C. erythraea, J. communis, P. ostruthium, and S. officinalis trigger the TAS2R4 receptor more while A. millefolium, C. erythraea, P. ostruthium, S. officinalis, and T. officinale trigger the TAS2R39.
Polyphenol Content
Finally they tested each extract to see what the relative polyphenol contents were. Were some extracts richer in polyphenols than others? Would those extracts be the ones with the biggest effects on acid production?
As expected, the herbal extracts with the highest polyphenol content, as per Folin-Ciocalteu reagent testing, were in order of magnitude: sage, juniper, yarrow and masterwork. Gentian, wormwood and centaury containing around 10 times less and dandelion and chicory the least.
The herbal extracts with the most polyphenols were also the ones that triggered a stronger acid producing effect from the stomach cells.
Lab or life?
The important thing to note about all of these experiments is that they are on cells in a dish and not on our actual stomachs. These effects might be a lot weaker in reality when the extracts are diluted and mixed up with everything else we eat. As the researchers themselves explained in a university press release, these are preliminary results with a lot more work to be done.
Nevertheless, the researchers are excited about what they found: ‘Comparing the different extract mixtures yielded particularly interesting results,’ explains Phil Richter. ‘The combination containing all nine plant extracts produced the strongest stimulation of cellular proton secretion. In contrast, the mixture composed of the four most active individual extracts showed a considerably weaker effect, while the blend of the five least active extracts triggered only a slight increase in proton secretion.’
It looks like the digestion helping effects come from the triggering of a combination of several bitter receptors in the stomach. ‘Our data suggest that several bitter taste receptor types are activated simultaneously,’ says Phil Richter. ‘Apart from polyphenols, other plant constituents are also likely to contribute to this synergistic effect,’ adds Veronika Somoza.
What does this mean for us?
So what do we do with this? Firstly now we know herbal extracts dissolved in alcohol might, at high concentrations in our stomach, provoke some acid production. On the other hand, we don’t yet understand how well water soluble versions work or whether the herbs themselves are any good.
More intriguingly, now we know that experiencing the bitter taste isn’t necessary to its action after all; maybe we can forego some of grandma’s unpleasant rituals.
As for me? Next time my local herbal enthusiast insists that I drink a nice big cup of bitter dandelion tea to help digest a big dinner, I know I’ll be asking for a G and T with a sage garnish instead.
Source
Richter P, Piqué-Borràs MR, Künstle G, Somoza V. A Digestive Herbal Mixture Preparation Stimulates Proton Secretion in Human Parietal Cells through Phenolic Compounds Targeting Bitter Taste Receptors. Molecular Nutrition & Food Research. 2026;70(6):e70443. doi:10.1002/mnfr.70443
