A study based on data of worldwide 186 countries was published in an open journal named BMS Public Health. The journal said that insufficient exposure to UVB light from the sun can increase the risk of colorectal cancer, particularly in old age groups.
The University of California San Diego, USA found out the possible association between the global levels of UVB light in 2017 and the rates of colorectal cancer for different countries and age groups in 2018. The researchers investigated that lower USB rays were significantly correlated with high rates of colorectal cancer across 186 different countries from 0 to 75 years in people.
The author also suggested that insufficient UVB exposure can reduce the level of vitamin D in the human body. Even deficiency of vitamin D has proven to be associated with the increasing risk of colorectal cancer. So we can say vitamin D deficiency increases the chances of colorectal cancers even more.
In April 2017, the authors used UVB estimates obtained by the NASA EOS Aura spacecraft and also took data on colorectal cancer rates in 2018 for 186 countries from the Global Cancer database. Data on skin pigmentation, life expectancy, stratospheric ozone, and other factors which may influence the health from UVB exposure was also collected. Countries that can be counted inside lower UVB included Norway, Denmark, and Canada, and countries with higher risk include UAE, Sudan, Nigeria, and India.
Other factors which can affect UV-b exposure and vitamin d levels are vitamin d supplements, pollution be or water, and clothing which was not included in the study. The studies which observe the data under particular countries do not show the conclusion or the effects attach to it. Therefore we can say more studies and research work is required to understand the appropriate relationship between UVB and vitamin D with colorectal cancer.