Chili peppers are enjoyed by billions of people every day. They are rich in capsaicin, the natural chemical responsible for their spicy taste.
Scientists have spent years studying capsaicin because it has shown both helpful and harmful effects in different experiments.
A new review published in Frontiers in Nutrition looked at whether people who eat a lot of chili peppers have a higher risk of cancers affecting the digestive system.
The researchers reviewed evidence from 14 observational studies involving more than 11,000 adults.
Gastrointestinal cancers include cancers of the esophagus, stomach, colon, and rectum. These diseases remain some of the leading causes of cancer deaths worldwide because they are often discovered after they have already spread.
When the researchers compared people with the highest chili pepper intake with those who ate the least, they found a higher overall risk of digestive cancers. The strongest association involved esophageal cancer, while the evidence for stomach and colorectal cancers was much weaker.
Scientists have proposed several reasons for these findings. Repeated exposure to very spicy foods might irritate the lining of the esophagus in some people. However, laboratory studies have also shown that capsaicin can reduce inflammation and even kill certain cancer cells under some conditions, making the overall picture much more complicated.
The results also varied depending on where the studies were conducted. Higher risks were generally reported in Asia, Africa, and North America, whereas European and South American studies often found no increased risk. These differences may reflect variations in cooking methods, lifestyle, alcohol use, smoking, infections, genetics, and the types of peppers commonly eaten.
One of the biggest unanswered questions is how much chili pepper is too much. The available studies mainly compared people with the highest intake to those with the lowest intake. They do not clearly show whether moderate consumption carries any extra risk.
The authors stressed that their review found an association, not proof of cause and effect. Because all of the included studies were observational, other factors could explain part or all of the increased cancer risk. For example, people who eat large amounts of spicy food may also differ in other health habits that influence cancer risk.
Other recent reviews have reached mixed conclusions. Some suggest spicy foods may offer health benefits for heart disease and overall survival, while evidence for digestive cancers remains inconsistent. This means the health effects of chili peppers are likely more complex than a simple good-or-bad answer.
This study provides useful information but should not cause unnecessary alarm. Its strength lies in combining many previous studies, but stronger long-term research is still needed before firm dietary recommendations can be made. Overall, enjoying chili peppers in moderation appears sensible until scientists better understand how very high intake may affect long-term cancer risk.
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