A team from the University of California San Diego has conducted a new study that builds on a long-standing hypothesis linking vitamin D deficiency to a greater risk of colorectal cancer. They found that countries where people experience lower levels of UVB light report higher rates of colorectal cancer (also called rectal cancer or colon cancer, depending on where they start.)
However, while some researchers have detected a strong link between low vitamin D levels and colorectal cancer, others have questioned the relationship, finding little evidence of a correlation between the two.
This new study looked at global UVB light exposure levels across 186 countries. The team accounted for various factors, such as smoking and skin pigmentation, while also adjusting for age. They found a distinct age-dependent inverse link between UVB exposure and colorectal cancer. The association was statistically significant for people over the age of 45.
Raphael Cuomo, the study’s co-author, said:
Differences in UVB light accounted for a large amount of the variation we saw in colorectal cancer rates, especially for people over age 45. Although this is still preliminary evidence, it may be that older individuals, in particular, may reduce their risk of colorectal cancer by correcting deficiencies in vitamin D.
A 2013 study, published in the National Library of Medicine, found a similar relationship between UVB exposure and colorectal cancer. The results of this new study are on par with those prior findings.
In addition, the recent study’s age-dependent assessment indicates that vitamin D deficiency plays a more prominent role in the inception of colorectal cancer, particularly in older people. The researchers suspect this could be due to chronic vitamin D deficiency increasing one’s colorectal cancer risk.
The UC San Diego team conclude:
This study supports the need for adequate public health programs to avoid vitamin D inadequacy at national and global levels, whether through screening those at risk, through selective supplementation or through population-based measures such as food fortification. In addition, future studies can aim at identifying the cancer types which show significant improvement with vitamin D supplementation.
The new study was published on July 5, 2021, in the journal BMC Public Health.
Last year, scientists from Japan’s Nagoya University demonstrated how a portable UV LED device could offer vitamin D when it’s not available in sufficient amounts via sunlight.
