Research Highlights: Type 2 Taste Receptors and Polyphenols

A recent research published in the Food Bioscience journal highlighted a critical connection between Type 2 taste receptors (T2Rs) and the regulation of appetite and blood glucose levels. While these receptors are traditionally associated with taste buds that perceive bitter flavors, they are also expressed in the gastrointestinal (GI) tract, where they play a significant role in homeostatic regulation.

The T2Rs of the GI tract are activated by various ligands, including the bioactive compounds known as polyphenols, which are commonly found in plant-based foods. When these receptors are activated, they trigger the release of gastrointestinal hormones such as:

• Cholecystokinin (CCK)
• Incretin hormones like glucose-dependent insulinotropic polypeptide (GIP)
• Glucagon-like peptide-1 (GLP-1)

These hormones have profound effects on appetite regulation, GI motility, and blood glucose homeostasis.

Cholecystokinin (CCK) and GLP-1 are peptides that play critical roles in managing food intake and appetite. CCK slows down gastric emptying, which prolongs the feeling of fullness after a meal, while GLP-1 improves insulin secretion in response to glucose, thereby helping in blood glucose control. Incretins like GLP-1 and GIP are particularly important as they stimulate insulin release by contributing to the maintenance of blood glucose levels within a healthy range.

One of the major insights from the research is the role of polyphenols, which are known for their strong bitter taste, are not well absorbed in the upper digestive tract. But, they travel through the digestive system to the colon, where they are excreted. However, during their journey through the GI tract, polyphenols interact with T2Rs, particularly in the GI tract, where they appear to trigger beneficial effects.

Epidemiological and intervention studies have consistently shown a negative correlation between polyphenol intake and the risk of developing diabetes. The proposed mechanism behind this protective effect involves the activation of T2Rs by polyphenols, which in turn leads to improved glucose tolerance and better regulation of appetite and intestinal motility.

The review suggests that the activation of T2Rs by polyphenols could be an important factor with their ability to modulate glucose metabolism and control appetite by offering a potential pathway for dietary interventions to prevent metabolic disorders like diabetes. Overall, the findings illuminate the importance of considering the bitter components of our diet, like polyphenols, not just for their nutritional value but also for their potential role in regulating key physiological processes.

Source

Osakabe, N., Ohmoto, M., Shimizu, T., Iida, N., Fushimi, T., Fujii, Y., Abe, K., & Calabrese, V. (2024). Gastrointestinal hormone-mediated beneficial bioactivities of bitter polyphenols. In Food Bioscience (Vol. 61, p. 104550). Elsevier BV. https://doi.org/10.1016/j.fbio.2024.104550