Have you ever wondered why you can eat a raw habanero with no problem while your friends and family think you’re crazy? Genetics just might be on your side (or against you depending on how you look at it). The gene TRPV1 is a heat-gated ion channel that is expressed in most heat-sensitive nociceptive neurons (Mckemy, 2011). It also is a receptor for capsaicin which is the active chemical in spicy peppers. Capsaicin binds to TRPV1 receptors sending a signal to the brain which is interpreted as heat and if it is activated enough, is interpreted as pain. The crazy part is that massive neuronal calcium influxes triggered by topical exposure to sufficient concentrations of capsaicin is potentially cytotoxic, which triggers a reflex down-regulation of TRPV1 activity. This means that the neurons become less responsive when TRPV1 is exposed to capsaicin resulting in analgesic effects (Mccarty et al., 2015).
That still does not explain why some people can tolerate spicier foods than others. Well, it is thought that some people just have less TRPV1 receptors (Törnwall et al., 2012). This means that when they eat that raw habanero, some capsaicin binds the receptors that are available, resulting in neuronal impulses that might only be interpreted as heat. Others with more receptors will get more neural impulses that will be interpreted as pain. It is also thought that you can desensitize these receptors overtime by eating more spicy food more frequently (Crane, 2015). There is also some research suggesting that those with thrill-seeking personalities just might like spicy foods because it is fun (Byrnes et al., 2013).
Byrnes, N. K., & Hayes, J. E. (2013). Personality factors predict spicy food liking and intake. Food Quality and Preference, 28(1), 213-221. doi:10.1016/j.foodqual.2012.09.008
Crane, B. (2015, February 23). To Enjoy Spicier Food, Train Your Nervous System. Retrieved October 13, 2020, from https://www.theatlantic.com/health/archive/2015/02/learning-to-handle-spicy-food/385606/
Mccarty, M. F., Dinicolantonio, J. J., & O'keefe, J. H. (2015). Capsaicin may have important potential for promoting vascular and metabolic health: Table 1. Open Heart, 2(1). doi:10.1136/openhrt-2015-000262
Mckemy, D. D. (2011). A spicy family tree: TRPV1 and its thermoceptive and nociceptive lineage. The EMBO Journal, 30(3), 453-455. doi:10.1038/emboj.2010.350
Törnwall, O., Silventoinen, K., Kaprio, J., & Tuorila, H. (2012). Why do some like it hot? Genetic and environmental contributions to the pleasantness of oral pungency. Physiology & Behavior, 107(3), 381-389. doi:10.1016/j.physbeh.2012.09.010
I am definitely one of the people who can attest to the fact that eating spicier foods more frequently can desensitize your capsaicin receptor and allow you to build a tolerance to spice over time. After years of eating hot Cheetos, I can finally eat a jalapeno without crying. Truly an inspiring story with a scientific basis.
ReplyDeleteAnyways, I have a friend who this post perfectly applies to. They have eaten the ghost pepper without issue and were unfazed by pepper spray. They know that it is hot, but they do not think that any of it is painful. I had never really thought about why that was the case though, but it would make sense that they just have less of the receptors that would detect capsaicin; thereby interpreting the capsaicin as heat rather than pain as you stated in your article. It is definitely cool to see an explanation of something that most of us have noticed at some point in our everyday lives.
This makes me wonder if there is a similar relationship to our interpretation of pain in general. Do people with higher pain tolerances just have fewer or less responsive pain receptors? Obviously there is a component of mental toughness, but I don’t think that we’ll ever be able to effectively account for that.