A recent study suggests that a specific amount of daily light exposure may significantly reduce the risk of developing pancreatic cancer. Researchers analyzed the light exposure of nearly 90,000 adults and found an association between higher daytime light levels and a lower incidence of gastrointestinal cancers, particularly pancreatic cancer.
The study, published in the International Journal of Cancer, followed participants for nearly a decade, using wearable sensors to measure light intensity. The findings indicate that exposure to at least 1,900 lux of brightness between 7:30 a.m. and 8:30 p.m. was linked to a 13 percent lower risk of gastrointestinal cancer. This level of brightness is comparable to being outdoors on a cloudy day.
Pancreatic Cancer Risk Reduction
The effects were more pronounced for pancreatic cancer. The research found that two hours of exposure to light exceeding 5,000 lux—equivalent to an overcast morning or afternoon—was associated with a 42 percent lower risk of developing the disease. This level of light exposure was also linked to a 53 percent reduced chance of death from pancreatic cancer.
While the exact mechanisms are still being investigated, scientists hypothesize that sunlight plays a role through vitamin D production. Vitamin D, synthesized by the skin upon sun exposure, is known to help promote cancer cell death and inhibit tumor blood vessel growth. Additionally, daytime light exposure helps regulate the body's circadian rhythm, which can bolster the immune system and aid in DNA repair.
"Higher daytime light exposure was associated with lower risks of gastrointestinal cancer incidence and mortality, especially for pancreatic cancer, indicating a potential protective effect that warrants further investigation in prevention and prognostic contexts," the researchers from Guangdong Medical University wrote.
The study utilized data from the UK Biobank, involving 89,069 adults aged 44 to 79 who were recruited between 2013 and 2015. During the nine-year follow-up period, 1,692 participants developed gastrointestinal cancer, and 891 died from it. The researchers noted that the association was particularly strong for pancreatic cancer, with no statistically significant differences observed for other gastrointestinal cancers like colon cancer, suggesting a specific impact on the pancreas.
Pancreatic cancer is a significant health concern in the U.S., with approximately 67,000 new cases and 52,000 deaths annually. Notably, diagnoses have been increasing among younger age groups, with a 4.3 percent annual increase among those aged 15 to 34 and a 1.5 percent annual increase among those aged 35 to 54 between 2000 and 2021.
The researchers cautioned that their findings demonstrate an association rather than direct causation. The study aimed to address a gap in direct evidence linking daytime light exposure to gastrointestinal health outcomes. Previous research has focused on factors such as processed meats, exercise, and obesity in relation to pancreatic cancer prevention.