HMN 2026: How Bitter taste receptors at the interface between nutrition, the endocrine system and health

A bitter taste has always been considered a warning signal, devoted to protecting us from ingesting potentially harmful substances. But bitter taste receptors can apparently do much more than just evaluate the taste of food. A study by the Leibniz Institute for Food Systems Biology at the Technical University of Munich now shows that certain human bitter taste receptors also respond to steroid hormones. They could therefore play a previously underestimated role in physiological processes.

The study, published in the Annals of the New York Academy of Sciences, focused on the approximately 25 different types of human bitter taste receptors. While these receptors are mainly known for perceiving bitter food constituents in the oral cavity, they are also found on blood cells, sperm cells, and cells of internal organs. These include, for example, the brain, heart, and gastrointestinal tract.

Since some of these organs have no direct contact with the outside world, the question has long been asked as to which substances activate these receptors there.

Steroid hormones as powerful activators

Using a cellular test system and computer-assisted simulations (docking experiments), the study now provides new evidence that steroid hormones such as progesterone, testosterone and hydrocortisone could act as endogenous activators of human bitter taste receptors.

In extensive functional tests, the researchers examined a total of 19 steroid hormones, cholesterol, and two hormonally active plant compounds. These include genistein, which can be found in relatively high concentrations (up to 18.7 mg/100 g) in soy products such as tempeh.

“Our analyses show that the bitter taste receptor types TAS2R14 and TAS2R46 respond to steroid hormones, with the latter receptor type being particularly sensitive,” reports Tatjana Lang, first author of the study, adding, “Several hormones activate this receptor even at concentrations that can be reached in the blood during pregnancy or under stress, for example.”

What does this mean for humans?

“The results of our food systems biology research suggest that bitter taste receptors not only serve as sensors for potentially harmful food components, but could also act as signal transmitters for hormonal states in the body,” says principal investigator Maik Behrens.

This is particularly interesting in connection with known phenomena such as altered taste perception during pregnancy or extreme stress situations, as well as possible effects on blood pressure, heart function, or gastrointestinal activity, the scientist continues.

Genetic differences also play a role

In addition, not all humans have functionally identical bitter taste receptors. About 8% of the population carries a genetic variant of the receptor type TAS2R46 that is non-functional.

“Our study suggests that such genetic differences could lead to measurable differences in taste perception and physiological responses to food constituents and hormones. This is an exciting starting point for future personalized research, which we intend to pursue further,” adds Behrens.

The research team agrees: the recent discovery that steroid hormones are also activators of human bitter taste receptors significantly expands our current understanding of these receptors.

Are steroid hormones real flavorings?

Whether steroid hormones are real flavorings, endogenous agonists, or both remains to be seen. It is known that hydrocortisone actually tastes bitter. Hydrocortisone is synthetically produced cortisol, which has anti-inflammatory, anti-allergic, and immunosuppressive effects. In addition, a study has shown that cortisol can reach concentrations of 8.69 micromolar [µM] in saliva under stressful conditions.

This concentration is already close to the half-maximal activation concentration for the bitter taste receptor TAS2R46 and should cause a bitter perception. Previous studies have shown that people rated the bitter aftertaste of a saccharin solution as more bitter under stressful conditions, while the perception of the sweetness of the sweetener solution remained unchanged.

According to the current study, this taste phenomenon could be explained by the stress-related increase in cortisol levels in saliva.

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