Eating chili peppers linked to substantially higher esophageal cancer risk

A large review of 14 observational studies suggests a link between high chili pepper consumption and a greater risk of gastrointestinal cancers, particularly esophageal cancer, which was nearly three times more likely in the heaviest consumers. However, the findings show association, not causation, and researchers emphasize that factors like regional diet, genetics, and lifestyle could be influential. The risk associated with moderate consumption remains unclear.

Chili pepper cancer risk analysis

• ▪An umbrella review examining multiple systematic reviews concluded that spicy foods and capsaicin appear to have both potential health benefits and possible risks
• ▪The analysis found that individuals with the highest chili pepper intake were about 64% more likely to develop gastrointestinal cancers overall
• ▪A review of 14 observational studies combined data from over 11,000 participants, including over 5,000 people diagnosed with gastrointestinal cancers
• ▪The review did not find a statistically significant increase in the risk of stomach or colorectal cancer from high chili pepper consumption

Esophageal cancer association

• ▪Gastrointestinal cancers, including those of the esophagus, stomach, and colon, account for millions of new cancer diagnoses worldwide each year
• ▪The strongest association found was for esophageal cancer, with the highest consumers being nearly three times more likely to develop it than the lowest consumers

Regional variation in findings

• ▪In contrast, studies from Europe and South America found either no increased risk or potentially lower risks associated with chili peppers
• ▪Studies from Asia, Africa, and North America generally found higher cancer risks among people with the greatest chili pepper consumption
• ▪Researchers suggest regional differences could be due to factors like cooking methods, pepper varieties, genetics, smoking, and alcohol use

Capsaicin mechanism hypotheses

• ▪Chili peppers' heat comes from capsaicin, a compound that has shown conflicting effects in lab studies, sometimes killing cancer cells and other times promoting irritation
• ▪One hypothesis suggests that repeated exposure to capsaicin could cause chronic irritation of the esophageal lining by activating TRPV1 receptors

Observational study limitations

• ▪The review included only observational studies, which can identify associations but cannot prove that chili peppers themselves cause cancer
• ▪The observed associations could be influenced by other factors such as smoking, alcohol consumption, socioeconomic differences, or overall dietary patterns

Dose threshold questions

• ▪It remains unclear whether moderate chili pepper consumption carries the same risks as those observed among the heaviest consumers
• ▪Future studies that follow people over many years are needed to determine if chili peppers play a direct role in cancer development