Bitter taste receptors in the intestine could play a key role in aging.

Bitter taste receptors are specialised proteins that enable us to detect substances with a bitter taste. They are found mainly in the taste buds of the tongue, but also in the intestine, lungs and even the brain. These receptors are part of a family called TAS2R and they play a vital role in human health because they function as a warning system in case of ingestion of toxic or potentially harmful substances. However, in recent years it has been discovered that these receptors do more than just warn us if something tastes bad. They also influence how the body manages energy, releases digestive hormones and responds to dietary compounds. Now, a research team led by the Universitat Rovira i Virgili (URV) and involving the IDIBAPs, the Hospital Clinic and the Faculty of Pharmacy and Food Sciences of the UB has discovered that two of these receptors could play a key role in processes associated with aging. 

The study, published in the Journal of Nutritional Biochemistry, compared the presence of the TAS2R5 and TAS2R38 receptors in colon samples from two groups of healthy men and women: a younger group with an average age of 39 and an older group with an average age of 64. In all participants, the abundance of the main receptors of bitter taste was analysed and related to clinical analyses and the presence of phenolic compounds in their blood, which was determined using statistical analysis and artificial intelligence tools. These tools were trained to select the parameters that best distinguished individuals according to age and accordingly selected, among others, the bitter taste receptors TAS2R5 and TAS2R38.

The results showed that, as the body ages, various metabolic and inflammatory biomarkers in the blood increase. Among the most differentiating factors were polyunsaturated fatty acids such as the well-known DHA (docosahexaenoic acid), various types of lipoproteins and the two bitter taste receptors TAS2R5 and TAS2R38. According to the research team, this suggests that these receptors could be indicators of, or even active agents in, the physiological changes associated with age.

The elements that best differentiated between young and old people were docosahexaenoic acid (a type of omega-3) and various lipoprotein fractions (fatty acids transported in the blood). However, the two bitter taste receptors, TAS2R5 and TAS2R38, were also identified, the former being associated with different types of lipoproteins, polyunsaturated fatty acids and interleukin-6 (a marker of inflammation), and the latter having a more specific relationship to certain parameters such as sphingomyelin (a fatty acid that forms part of cell membranes), acetone (which is produced when the body burns fatty acids) and some omega acids.

Both TAS2R5 and TAS2R38 were correlated with β-hydroxybutyrate, a molecule that the body generates in certain metabolic situations. The results obtained point to bitter taste receptors playing a broader role in the regulation of metabolism and inflammation, particularly as we age. "Our study shows that these two receptors may play a key role in our understanding of how we age. And because they are found in the large intestine, we may be able to develop approaches to promote healthier aging based on their interaction with food and the microbiota of the colon," says Anna Ardévol, director of the study and member of the MoBioFood group (URV).