The fascinating part is that your anal tissue has that level of sensitivity and insight.
I think they've pooped out the difference.
It is important to remember that herbs are difficult to study in this setting compared with isolated compounds -- likely because their pharmacological and chemical compositions are sensitive to many factors: hour and season of harvest, form consumed (raw powder, alcohol extract, cold water infusion, fat emulsion, hot water infusion, combustion, pyrolysis, essential oil), part consumed (leaf, root, flower, seed), among staggeringly many others. Anyone with experience consuming cannabis or coffee can probably testify to the above
Not to mention that the pharmacologically active compounds in many plants are far from being comprehensively understood, let alone their interactions and dynamics
This isn't to say that every claim about herbs is to be taken seriously. My point here is more that there is no good reason to dismiss the herb itself as a cause yet simply because it's an herb and a fairly mundane one at that. There are easy examples of herbs which have pronounced physiological effects, used for recreation, performance enhancement, as literal poison, to induce labor, to thin the blood -- among others.
This particular path isn't that crazy, but it would only be for a subset of folk. From the study there is something simpler: menthol acts as a natural calcium-channel blocker, triggering vasodilation to reduce blood pressure.
This is what I sound like when I talk about analogue electronics, isn't it?
Thing is I know I could look all those terms up and learn enough to be dangerous in a subject you're clearly very good at.
Lightly edited from Wikipedia:
"Menthol's [agonism of] the cold-sensitive Transient Receptor Potential cation channel subfamily M (melastatin) member 8 or TRPM8 receptors is responsible for the well-known cooling sensation it provokes.
Menthol's analgesic properties are mediated through a selective activation of κ-opioid receptors. Menthol blocks calcium channels and voltage-sensitive sodium channels, reducing neural activity that may stimulate muscles.
Some studies show that menthol acts as a GABAᴀ receptor positive allosteric modulator and increases GABAergic transmission in PAG neurons."
…and! Check this out:
"Menthol has anesthetic properties similar to though less potent than propofol, interacting with the same sites on the GABAᴀ receptor."
Propofol. PROPOFOL. The -ol in propofol is the -ol in menthol, haha.
"Menthol may also enhance the activity of glycine receptors and negatively modulate 5-HT3 receptors and nAChRs."
Aaaaand:
"Menthol also lowers blood pressure and antagonizes vasoconstriction through TRPM8 activation."
My point was exactly the hope to indicate how much knowledge there exists. That's the truly wild thing. Or yeah, how unread most of it lays.
The EGCG is probably what is reducing the blood pressure.
Transient receptor potential vanilloid type 1 is vital for (−)-epigallocatechin-3-gallate mediated activation of endothelial nitric oxide synthase
https://onlinelibrary.wiley.com/doi/10.1002/mnfr.201400699
Cardioprotective and Anti-Hypertensive Effects of Epigallocatechin Gallate: Novel Insights Into Biological Evidence
https://onlinelibrary.wiley.com/doi/full/10.1111/jch.70036
Anything with EGCG in it causes me extreme bladder pain, even peppermint tea. While taking tons of Ricola cough drops (high in mentol) once when I had covid I found my bladder pain vanished. I then learned how the TRPV1 receptor is involved in my bladder pain.
https://www.nature.com/articles/s41598-018-24056-0
I
Peppermint as a scent is usually thought of as stimulating, raising heart rate and blood pressure. The lore, with some research supporting it, is that other oils that are more sedating can bring down blood pressure if you use them, say, in a diffuser.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3521421/
I find the sensuality of Ylang Ylang to be distracting so I mixed in Lavender and got this wonderful floral smell that filled my office but an hour later I notice the sedation and I am nodding off and can't concentrate on work at all. It was like the scene in the Wizard of Oz where the Wicked Witch of the West put (most of) the protagonists to sleep with a field of scarlet poppies.
http://phenol-explorer.eu/contents/food/869
https://onlinelibrary.wiley.com/doi/full/10.1111/jch.70036
https://academic.oup.com/chemse/article-abstract/40/1/27/290...
Mints are closely related to pennyroyal (Mentha pulegium), which was traditionally (and dangerously because of toxicity) used as an abortifacient. Its mechanism of action is still unknown, so hormone modulating effects seem plausible to me.
At least this study says the activity was reduced, not significantly though: https://www.sciencedirect.com/science/article/abs/pii/S02786...
If we cue university student volunteers on Toothpaste -> Selfcare -> Weightloss I wonder what happens.
I also wonder what placebo was used, and to what effect. The typical flavoring agent to make something peppermint-flavored is peppermint essential oil (or cornmint, spearmint, etc), and I don't know how you'd make it convincing without also including a bunch of hypothetically active compounds. The paper lists Schweppes Peppermint Cordial, without mint on the ingredients label. "Peppermint cordial" used as flavoring was historically 10% peppermint oil, and today the Schweppes product they cite just lists "flavourings" as ingredient.
Because the FDA regulates beverages separately from food (or at least alcoholic ones - not sure where the dividing line lies), you can sell booze flavored with things that you cannot put in snacks.
Lead and live tapeworm eggs are still out, though - for now.
That is significant.
Of course, you would have to do a real study to see side effects versus current blood pressure medication, but if there is no real harm in peppermint, the 6% drop over an adult lifetime might make a large difference in vascular health.
I wouldn't put my hopes up that peppermint oil has anything to do with it.