When you eat a chili pepper, a substance called capsaicin is what brings the spicy heat. Capsaicin is so potent that it's even used in bear repellant spray. Some people may find that capsaicin can irritate their stomach, and evidence is unclear on its role in digestion.
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More Than Just Burn
A report published in August 2019 in Clinical Practice and Cases in Emergency Medicine highlights the intensity of capsaicin, the substance that determines the level of heat in a chili pepper. The report says the alkaloid can cause tissue irritation and burning that can send people to the hospital.
But a June 2016 review in the Journal of Complementary & Integrative Medicine (JCIM) describes the many ways capsaicin is used to provide relief from gastrointestinal discomfort caused by gut inflammation, gastroesophageal reflux disease and indigestion.
Rajsree Nambudripad, MD, an integrative medicine specialist with St. Jude Medical Center in Fullerton, California, explains one of these protective mechanisms:
"Some people have low production of salivary enzymes and pancreatic enzymes, which makes it hard for them to properly break down food," she says. "Capsaicin causes the digestive tract to produce more of a mucous barrier, which acts as a protective shield in the gut. It also stimulates more salivary enzyme and pancreatic enzyme production, which can lead to better digestion."
Other Roles for Capsaicin?
Researchers are intrigued by the potential power of capsaicin, as shown by the sheer volume of studies on the pepper byproduct so far. There are several potential therapeutic roles for capsaicin and your GI tract being explored:
For one, capsaicin may play a role in ulcer healing. A July 2016 review in Critical Reviews in Food Science and Nutrition notes that capsaicin slows acid secretion and promotes mucus secretion and mucosal blood flow which can be helpful in preventing and healing gastric ulcers.
In addition to stimulating digestive enzymes, capsaicin "can also activate the immune response to help the body fight off any gut infections or bacterial imbalances," Dr. Nambudripad says. On that point, the JCIM also lists capsaicin's role in the slowing of pathogens in the gut as therapeutic potential.
Therefore, capsaicin might just help you avoid or fight off that gastrointestinal discomfort caused by bacteria or a virus.
Also, researchers at the University of Connecticut have discovered, in mice, connections between receptors in the brain, immune system and gastrointestinal tract. Specifically, their research, published in April 2017 in the journal Proceedings of the National Academy of Sciences, found that when capsaicin was consumed by rice, receptors in the gastrointestinal tract send signals that told the gut's immune system to calm down.
The researchers believe that the reason behind this is because capsaicin binds to a receptor, called TRPV1, found on cells in the gastrointestinal tract. Once bound, these cells make a new compound that activates immune cells that calm inflammation in the stomach, esophagus and pancreas.
While all of this sounds good, and promising, the U.S. National Library of Medicine says that there is insufficient evidence to rate effectiveness for capsaicin for indigestion, IBS, diarrhea or stomach ulcers just yet. More human studies are needed on this red-hot fruit (that's right, it's technically a fruit).
What to Do
Though more research is needed to fully understand the effect of capsaicin on human digestive health, it's clear that some people find relief from gastrointestinal discomfort when they consume capsaicin-rich chili peppers, but others don't tolerate spicy foods very well.
Some people are sensitive to the alkaloids and lectins in peppers, explains Dr. Nambudripad. "If you are new to chili peppers, it's best to start slow and gradually increase the amount to see how much you can tolerate," she says.
The best way to figure out if capsaicin or other spicy foods affect you is by trying them and observing your response. Pay attention to how you feel after eating spicy food, says Dr. Nambudripad. "Do you get any stomach pain, heartburn or digestive upset? Any joint pains? Or do you feel great?" she asks. "It's best to listen to your body and determine if capsaicin is something you can tolerate."
- Rajsree Nambudripad, MD, integrative medicine specialist, St. Jude Medical Center, Fullerton, California
- Clinical Practice and Cases in Emergency Medicine: “Capsaicin: An Uncommon Exposure and Unusual Treatment”
- Proceedings of the National Academy of Sciences of the United States of America: “Endocannabinoid System Acts as a Regulator of Immune Homeostasis in the Gut”
- Journal of Complementary & Integrative Medicine: “Phytochemistry and Gastrointestinal Benefits of the Medicinal Spice, Capsicum annuum L. (Chilli): A Review”
- Critical Reviews in Food Science and Nutrition: "Biological Activities of Red Pepper (Capsicum annuum) and Its Pungent Principle Capsaicin: A Review"
- U.S. National Library of Medicine: "Capsicum"