Many people enjoy spicy food, and chili peppers are an important part of diets around the world.
Besides adding heat and flavor, chili peppers contain capsaicin, a natural compound that has attracted attention because laboratory studies suggest it may reduce inflammation and even slow the growth of some cancer cells.
However, research in people has produced mixed results.
A large review published in Frontiers in Nutrition examined whether eating large amounts of chili peppers affects the risk of cancers of the digestive system.
These cancers include cancer of the esophagus, stomach, colon, and rectum, which together are responsible for millions of cases each year.
The researchers combined data from 14 observational studies involving more than 11,000 participants, including over 5,000 people with gastrointestinal cancers. By combining many studies, scientists hoped to obtain a clearer picture than any single study could provide.
The analysis found that people who ate the highest amounts of chili peppers were about 64% more likely to develop gastrointestinal cancers overall than those who ate the least. The strongest link was seen for esophageal cancer, where heavy chili pepper consumers had almost three times the risk.
The results were less certain for stomach and colorectal cancers. Although stomach cancer appeared to occur more often in heavy chili pepper consumers, the difference was not strong enough for researchers to rule out the possibility that it happened by chance. No clear increase was found for colorectal cancer.
The findings also differed across regions of the world. Studies from Asia, Africa, and North America generally suggested a higher cancer risk with very high chili pepper intake, while studies from Europe and South America found little or no increase in risk.
Researchers believe differences in cooking methods, pepper varieties, smoking, alcohol use, infections, genetics, and overall diet may all influence the results.
Scientists have suggested several possible explanations for why the esophagus might be more sensitive. Capsaicin activates pain receptors that create the familiar burning feeling. Some researchers think repeated exposure to very spicy foods could irritate the lining of the esophagus in some people, but this idea has not been proven.
It is important to understand that this review does not show that chili peppers cause cancer. All of the studies included were observational, meaning they could only identify links between eating habits and disease. They cannot prove that one directly caused the other because many other lifestyle factors may also play a role.
Other research has painted a more complicated picture. Some studies suggest spicy foods may lower the risk of heart disease or early death, while others have found possible risks for certain digestive cancers. This shows that the effects of chili peppers may depend on the amount eaten, a person’s health, and other dietary habits.
This review highlights an important question rather than providing a final answer. The study is strengthened by its large number of participants, but observational research has important limitations.
More long-term studies are needed to determine whether chili peppers themselves increase cancer risk or whether other factors explain the findings. For now, moderate consumption as part of a balanced diet appears reasonable, while extremely high intake may deserve further investigation.
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Source: Frontiers in Nutrition.
