Both the level of vitamin D in the blood and intake of vitamin D-rich foods decrease the risk of colorectal polyps in a number of studies.
Analyzing published studies of blood levels of vitamin D, researchers found a 30 percent decrease in the risk of adenomas among people with the most circulating vitamin D compared to those with the least. The highest vitamin D intake decreased adenomatous polyp risk by 11 percent.
In addition, there appeared to be an even stronger relationship between both blood levels and vitamin D intake for advanced adenomas, with the highest risk of cancer. Higher blood levels decreased risk of advanced adenomas by 46 percent, greater intake of vitamin D by 23 percent.
Melissa Wei and her colleagues concluded,
Both circulating 25(OH)D and vitamin D intake were inversely associated with colorectal adenoma incidence and recurrent adenomas. These results further support a role of vitamin D in prevention of colorectal adenoma incidence and recurrence.
SOURCE: Wei et al., Cancer Epidemiology, Biomarkers, and Prevention, Volume 17, Number 11, November 2008.