A recent clinical study examined a connection between vitamin D insufficiency and colorectal cancer risk in Black women. Several observational studies, mostly among White populations, have pointed to a connection between low vitamin D levels and colorectal cancer – Black people have the highest rates of colorectal cancer risk and death, and also have lower vitamin D levels compared with other populations. This is because aside from dietary supplements, sunlight is the predominant source of vitamin D for most people.
 
The study’s findings were in line with previous epidemiological studies to date. More than 150,000 people are diagnosed with colorectal cancer each year, making it the third-most common cancer in both men and women excluding skin cancer.
 
The study, conducted by the Boston University School of Medicine and Slone Epidemiology Center and appearing in Cancer Epidemiology Biomarkers, found a direct correlation between vitamin D dietary intake and blood concentrations of vitamin D in a select subgroup of participants among 49,5534 Black Women’s Health Study participants, tracking colorectal cancer outcomes as well. The prediction model used in the study weighted variables by how strongly they were associated with actual blood levels, and applied this model to all of the participants in the Black Women’s Health Study to get a predicted vitamin D score that would likely correspond to their actual level.
 
488 of the participants were diagnosed with colorectal cancer. Compared to women with the highest quartile of predicted vitamin D score, those in the lowest had an estimated 41% higher colorectal cancer risk.
 
Vitamin D plays a role in many cellular processes in the human body, and has been shown in some research to correlate with cancer risk, the authors of the present study said. Based on the present findings, they concluded that it is important to further substantiate the research so that individuals who are at increased risk can implement strategies to increase vitamin D levels in their bodies.