M Jenab at International Agency for Research on Cancer in Lyon, France and colleagues conducted a case-control study and found an inverse association between circulating vitamin D levels and risk for colorectal cancer.
Vitamin D deficiency has been associated with 17 types of cancer. Vitamin D is well known for its role in calcium homoeostasis and bone metabolism. But in the past decade, it has been found to play an incredible role in the innate immunity and potentially anticarcinogenesis.
This analysis was based on data from 1248 cases of incident colorectal cancer and the same number of matched controls who enrolled in the EPIC study. The study involved more than 520 000 participants from ten western European countries.
The analysis revealed that pre-diagnostic circulating vitamin D (25-hydroxy-vitamin-D, 25-(OH)D) concentration was inversely correlated with risk for colorectal cancer. It showed that compared to mid levels (50.0-75.0 nmol/l), low levels of vitamin D (<25.0 nmol/l) were associated with 32% increased risk for colorectal cancer. And high levels (≥100.0 nmol/l) were associated with 23% reduced risk for the cancer.
Compared to those in the lowest quintile of circulating vitamin D concentration, participants in the highest quintile were 40% less likely to be diagnosed with colorectal cancer.
Further analyses showed the association was strong for colon cancer, but not for rectal cancer.
Other studies indicated vitamin D may play an important role in cancer control by modulating cellular proliferation and apoptosis and by reducing angiogenesis.
Exposure to sun light is the main source for vitamin D. If a person does not get enough exposure to sunshine, he is likely vitamin D deficiency. Many studies have suggested maintaining vitamin D sufficiency can help prevent the majority of cancers like breast cancer.
An early study conducted by Edward D.Gorham at Naval Health Research Center in San Diego, California and colleagues showed that risk for colorectal cancer could be reduced by 50% in people with the serum vitamin D concentration at 33 ng/ml or higher, compared to those with only less than 12 ng/ml.
The study published in 2007 in American Journal of Preventive Medicine suggests that to reduce the risk by such a magnitude, one needs to take 1000 to 2000 IU of vitamin D3 daily. (JKZX.COM)
BMJ 2010; 340 doi: https://doi.org/10.1136/bmj.b5500
American Journal of Preventive Medicine Volume 32, Issue 3, March 2007, Pages 210-216