The article and comments don't mention it, but vagus stimulation by hot peppers (maybe wasabi too) has been studied and seems significant with respect to immune-nervous system interactions controlled by the vagus nerve, at least there's some interaction (wishful thinking perhaps, but as I like hot peppers this supports my view that they improve one's digestion and circulation):
(2013) "Capsaicin-sensitive vagal afferent neurons contribute to the detection of pathogenic bacterial colonization in the gut"
> "We conclude that activation of the afferent arm of the parasympathetic neuroimmune reflex by pathogenic bacteria in the gut is dependent on capsaicin sensitive vagal afferent neurons and that the release of inflammatory mediators into intestinal tissue can be directly sensed by these neurons."
More general current open-source review of the overall topic (2018):
"Vagus Nerve as Modulator of the Brain–Gut Axis in Psychiatric and Inflammatory Disorders"
(2013) "Capsaicin-sensitive vagal afferent neurons contribute to the detection of pathogenic bacterial colonization in the gut"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4188534/
> "We conclude that activation of the afferent arm of the parasympathetic neuroimmune reflex by pathogenic bacteria in the gut is dependent on capsaicin sensitive vagal afferent neurons and that the release of inflammatory mediators into intestinal tissue can be directly sensed by these neurons."
More general current open-source review of the overall topic (2018):
"Vagus Nerve as Modulator of the Brain–Gut Axis in Psychiatric and Inflammatory Disorders"
https://www.frontiersin.org/articles/10.3389/fpsyt.2018.0004...