Pudina chai and mint as digestif

The Daily Tea has a fine article on chai, with links to different approaches—chai with black tea, of course, but also green tea chai, with origins in Kashmir, and white tea chai.* The author, Carrie Keplinger, also described variations of black tea chai, including pudina chai. 

Pudina** chai “is black tea steeped with mint leaves in milk and water, sweetened to taste… Pudina chai makes a wonderful after-dinner digestif or a soothing remedy for an upset stomach.” Which is one great way to have an after-dinner mint!

Mentha arvensis, from Wikipedia

But why do we have an after-dinner mint as a “digestif?”

I believe the answer lies in mint’s ability to activate TRPA1, the cold receptor. You can find this receptor not just in the mouth and nose, where we sense the cold, but also all the way through the gut. In the gut TRPA1 is attached both to the gut lining cells and to specialized cells, enteroendocrine cells, that regulate gut motility.

When TRPA1 receptors attached to gut lining cells are activated, blood flow to the gut increases.*** When TRPA1 receptors on the enteroendocrine cells are activated, these cells release the hormone serotonin, which in turn causes the gut to start moving what you have eaten down the tract.****

Consequence? your digestion proceeds more quickly and smoothly, and you feel less over-filled! 

* http://www.thedailytea.com/taste/chai-style-delving-worlds-popular-spiced-tea/#prettyPhoto

** Despite the best efforts of my spell-check system, this word is not “pudding.” Pudina is the Hindi/Urdu name for a wild mint, Mentha arvensis, also know as corn mint and field mint.

*** Toru Kono, Atsushi Kaneko, Yuji Omiya, Katsuya Ohbuchi, Nagisa Ohno, Mas.ahiro Yamamoto. Epithelial transient receptor potential ankyrin 1 (TRPA1)-dependent adrenomedullin upregulates blood flow in rat small intestine. American Journal of Physiology - Gastrointestinal and Liver Physiology Feb 2013, 304 (4) G428-G436; DOI: 10.1152/ajpgi.00356.2012.

**** Nozawa K, Kawabata-Shoda E, Doihara H, et al. TRPA1 regulates gastrointestinal motility through serotonin release from enterochromaffin cells. Proceedings of the National Academy of Sciences of the United States of America. 2009;106(9):3408-3413. doi:10.1073/pnas.0805323106.