Can chili peppers reduce colorectal cancer risk?

Good news for spicy food lovers: according to a new study in the Journal of Clinical Investigation, capsaicin in chili peppers may reduce colorectal cancer risk.

Chili peppers originate in the Americas and are used worldwide as food and medicine. They have been part of diets in the Americas since around 7500 BC. With Europeans' arrival, they spread first to Spain and Portugal, then throughout Europe and the world.

Researchers found capsaicin activates a pain receptor called TRPV1 in mouse intestines, suppressing tumor development (a receptor is a cell responding to light, heat or external stimuli and sending signals to sensory nerves).

TRPV1 was first discovered in sensory neurons and found to protect cells from potential damage by heat, acids and spicy chemicals; it was therefore defined as a pain receptor, TRPV1.

TRPV1 suppresses intestinal tumors

The study found that intestinal epithelial cells stimulated by epidermal growth factor receptor (EGFR) also produce TRPV1. EGFR plays a critical role in intestinal cell growth.

Increased EGFR signaling can send growth out of control and increase tumor risk.

Researchers found that TRPV1, when activated by EGFR, provides “direct negative feedback” on EGFR, reducing unwanted intestinal growth and ultimately tumor risk.

Mice genetically modified to lack TRPV1 developed intestinal tumors much more frequently, leading researchers to state that TRPV1 mostly suppresses intestinal tumors.

Capsaicin was also observed to play a role in TRPV1 activation.

The role of capsaicin against colorectal cancer

Capsaicin produces heat in chili peppers. In mammals such as humans, it irritates tissues and creates a burning sensation on contact. It is also the active ingredient in pepper spray.

The team fed capsaicin to mice genetically prone to numerous intestinal tumors. TRPV1 became active, and they lived at least %30 longer than expected. These effects increased when combined with Celecoxib, a “COX-2 inhibitor” (a nonsteroidal anti-inflammatory drug).

These findings showed TPRV1 regulates intestinal cell proliferation. Dietary capsaicin activates TPRV1, suppressing intestinal tumor development.

In conclusion, combining a TRPV1 activator with a COX-2 inhibitor in humans could provide protection against adenoma and carcinoma-type cancers in the future.

Another very recent study presented evidence that prolonged capsaicin consumption reduces “cardiac hypertrophy and fibrosis” (heart muscle changes potentially causing heart attacks). Another suggested that suppressing the brain's capsaicin receptor with an experimental chemical might offer hope particularly for abdominal pain, emotional stress and anxiety. Studies also show gastrointestinal protective and therapeutic properties of capsaicin alone or combined with nonsteroidal anti-inflammatory pain relievers.

Since spicy products arrived from the Americas in Europe and spread worldwide, they have been major trade goods in many civilizations. Historically they were tried for conditions from insect stings to mushroom poisoning. Modern research is beginning to show potential benefits, particularly in the gastrointestinal system. Despite these benefits, I would not recommend a rapid start for those unaccustomed to them...