Enhanced exposure to UVB sunlight could potentially decrease the risk of colorectal cancer.

In a recent study published in the open access journal BMC Public Health, researchers from the University of California San Diego have investigated the association between ultraviolet B (UVB) exposure and colorectal cancer across 186 countries. The study, which used UVB estimates obtained by the NASA EOS Aura spacecraft and data on colorectal cancer rates from the Global Cancer (GLOBOCAN) database, found a significant correlation between lower UVB exposure and higher rates of colorectal cancer across all age groups.

The study found that countries with lower UVB levels, such as Norway, Denmark, and Canada, had higher rates of colorectal cancer, while countries with higher UVB levels, such as the United Arab Emirates, Sudan, Nigeria, and India, had lower rates. This association remained significant for those aged above 45 after considering factors like skin pigmentation, life expectancy, and smoking.

The authors of the study suggest that lower UVB exposure may reduce levels of vitamin D, which has previously been associated with an increased risk of colorectal cancer. The observational nature of the study does not allow for conclusions about cause and effect, and more work is needed to understand the relationship between UVB and vitamin D with colorectal cancer in more detail.

The study, conducted by researchers at the University of California San Diego, used data from 186 countries and investigated associations between global levels of UVB light and colorectal cancer rates for different age groups. Countries with particularly low UVB levels in the study include those with higher latitudes or cloudy climates, while countries closer to the equator or with sunnier climates show higher UVB values. Potential consequences of low UVB exposure include a higher incidence rate of colorectal cancer due to lower vitamin D synthesis stimulated by UVB radiation.

However, the authors caution that other factors may affect UVB exposure and vitamin D levels, such as vitamin D supplements, clothing, and air pollution, which were not included in the study. Future research could look directly at the potential benefits on colorectal cancer of correcting vitamin D deficiencies, especially in older age groups.

BMC Public Health is an open access, peer-reviewed journal focusing on the epidemiology of disease and public health, with a special focus on social determinants, environmental factors, behavioral correlates, and health policies. It is part of Springer Nature, a pioneer of open access publishing with a wide portfolio of high-quality peer-reviewed journals. The study is available for anyone to read and use, furthering the ongoing research into the relationship between UVB exposure, vitamin D levels, and colorectal cancer.