Sunday, April 21, 2013

Burn, Baby Burn

Spicy Food and Gastrointestinal Distress

Spicy foods are anecdotally responsible for many forms of gastrointestinal distress.   These range from heartburn after a visit to Chipotle™ to diarrhea and rectal burning (“if it burns going in, it will burn coming out”) after an evening of Thai cuisine.  None of this anecdotal evidence helps us get to the bottom of what causes the discomfort – there are too many factors involved.  The distress could be caused by overconsumption, by the presence of any number of spices, by the acid content or by high fat content in the meals.  For this post, we’ll try to look at the evidence that isolates on particular component of spicy foods – capsaicin. 

Capsaicin is the primary irritant in peppers from the chili family.  It irritates primarily by interacting with sensory neuron cells, causing a burning sensation and localized inflammation (though there is no associated tissue damage).(1)  This occurs on the skin, but is most pronounced on the mucous membranes (the eyes, nose, and GI tract).  At high concentrations, capsaicin can be incapacitating – hence it’s use in oleoresin capsaicin (OC) spray for self defense.

The amount of capsaicin varies based on the type of pepper.  The heat of peppers is measured in units called Scovilles, with higher numbers representing “hotter” foods.  Average Scoville units of common capsaicin-containing products are (estimated as they vary by up to 50% in foods) as follows:

Scoville Units
Pure capsaicin
Pepper spray
Custom-bred chili peppers (e.g. Naga Viper)
Habanero pepper, Scotch Bonnet pepper
Thai Chili peppers
Cayenne pepper, Tabasco pepper
Jalapeno pepper, Chipotle pepper
Banana pepper
 As a point of reference, the original Tabasco Sauce™ is rated between 2,500 and 5,000 Scovilles.(2)

The potential for gastrointestinal distress with capsaicin begins in the mouth and the associated mucous membranes present therein.  While individuals can build up a desensitization to the burning (3), most of us will be able to gauge the impact on the rest of the GI tract once a hot food hits our tongue (and the rest of the mouth).  Once irritation occurs, the only method of reducing oral burning is through the ingestion of non-capsaicin containing foods or drinks.  It isn’t water soluble, so plain water isn’t particularly effective (and will just move the capsaicin to other areas of the mouth).  Milk and sucrose solution are temporarily effective at cold temperatures, and eating additional food can mechanically absorb and remove the capsaicin slowly.(4)

Following the mouth, capsaicin impacts the esophageal mucosal lining upon consumption.  Though capsaicin has not been shown to cause heartburn nor to alter stomach emptying or pH values, it has been shown to have a perceived exacerbation.  The theorized reason for this is that the initial consumption of capsaicin causes a sensitization of the esophagus.  Subsequent reflux (including the capsaicin) exacerbates the pain felt by the subject, though it has not shown to have any additional erosive impact.  Additionally, there may be a longer-duration analgesic effect despite the proximal increase in perceived discomfort.(5)

Despite initial thoughts that capsaicin was a stomach irritant, direct viewing of the stomach suggests otherwise.(6)  Prior to the isolation of H. Pylori, eating spicy foods with capsaicin was thought to be a cause of ulcers.  Following the discovery and adoption of the H. Pylori causative reaction, many physicians still perceived capsaicin as exacerbating inflammation, increasing the likelihood of ulcer formation (and worsening it), and increasing acid production.  All of these have been disproven and, in fact, capsaicin is believed to have a mild positive effect on impeding the development of stomach ulcers, reducing acid production, and improving the outcomes for those with ulcers. (7,8) 

Of most interest to those with Crohn’s disease and Ulcerative colitis are the impact of capsaicin on the small and large intestines.  The main impact is the increase in transit time, resulting in less absorption of water and therefore looser stool.(9)  For those with IBD, this can further increase the already loose bowel movements and increase urgency.  While it hasn’t been studied well in IBD patients, capsaicin has been studied in those with IBS.  Specifically, a six week regime of capsaicin (blinded) showed that study participants had more abdominal pain and greater urgency with capsaicin than placebo, but that they developed a desensitization to capsaicin after approximately six weeks, resulting in lower pain and motility when eating spicy foods than those who had only had placebo. (10)  The primary pain associated with spicy foods, that of the “ring of death” and the rectum, is largely due to undigested capsaicin stimulating the C fibers (nerve receptors) in the rectal mucosa, similar to the mouth.

Overall, there has been surprisingly little research on capsaicin and IBD – most of the “spicy food” research is anecdotal.  Additionally, the majority of the research noted above is on small sample sets, and further confirmatory research is certainly warranted.

Bottom Line

·         Capsaicin, in spicy foods, can cause increased transit time (and subsequent diarrhea and urgency) and a burning sensation in the rectum.
·         Capsaicin likely doesn’t have any impact on GERD progression, but may make it feel worse temporarily.
·         Individuals can build up a tolerance to capsaicin over a short period of weeks.  There may be beneficial effect to capsaicin on the intestines, but results are all preliminary and not yet proven.
1.       Story, Gina M., and Lillian Cruz-Orengo. "Feel the Burn The linked sensations of temperature and pain come from a family of membrane proteins that can tell neurons to fire when heated or hot-peppered." American scientist 95, no. 4 (2007): 326-333.
3.       Karrer, Tracy, and Linda Bartoshuk. "Capsaicin desensitization and recovery on the human tongue." Physiology & behavior 49, no. 4 (1991): 757-764.
4.       Nasrawi, Christina Wu, and Rose Marie Pangborn. "Temporal effectiveness of mouth-rinsing on capsaicin mouth-burn." Physiology & behavior 47, no. 4 (1990): 617-623.
5.       Rodriguez-Stanley, S., K. L. Collings, M. Robinson, W. Owen, and P. B. Miner Jr. "The effects of capsaicin on reux, gastric emptying and dyspepsia." Aliment Pharmacol Ther 14 (2000): 129-134.
6.       Graham, David Y., J. Lacey Smith, and Antone R. Opekun. "Spicy food and the stomach." JAMA: the journal of the American Medical Association 260, no. 23 (1988): 3473-3475.
7.       Satyanarayana, M. N. "Capsaicin and gastric ulcers." Critical reviews in food science and nutrition 46, no. 4 (2006): 275-328.
8.       Abdel-Salam, O. M. E., J. Szolcsanyi, and Gy Mózsik. "Capsaicin and the stomach. A review of experimental and clinical data." Journal of Physiology-Paris 91, no. 3 (1997): 151-171.
9.       Gonzalez, R., et al. "Effect of capsaicin-containing red pepper sauce suspension on upper gastrointestinal motility in healthy volunteers." Digestive diseases and sciences 43.6 (1998): 1165-1171.
10.   Aniwan, S., and S. Gonlachanvit. "Effects of Chili on Abdominal Pain, Abdominal Burning and Rectal Sensation in Diarrhea Predominate Irritable Bowel Syndrome (IBS-D)." Thai J Gastroenterol 13, no. 1 (2012): 29-37.

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