Vitamin D and Colorectal Cancer Prevention:

Jacob Schor, ND

September 2007


In 2005, 145,300 people in the United States were diagnosed with colorectal cancer and a little more than a third of that number, 56,300 people died from the disease. There is a higher mortality rate from colorectal cancer in the northern and especially the northeastern states compared to the southwestern states, Florida, and Hawaii . This has led to a theory that vitamin D may exert a protective effect.


In the Women's Health Initiative study, no protective benefit was seen against colorectal cancer from low doses of vitamin D. It appears that higher doses are needed. This year the American Journal of Preventive Medicine published the results of a meta-analysis of five studies that looked at levels of vitamin D-3 (serum 25(OH)D. The results of all five studies were combined and this data examined.


The data were divided into groups by vitamin D levels and the odds ratios of getting colorectal cancer were calculated for each group. The higher the vitamin D level the lower the chance of getting cancer.


Vitamin D level (ng/mL)       Odds ratio     

6                                    1.00

16                                  0.82

22                                  0.66

27                                  0.59

37                                  0.46


As levels of vitamin D in the blood go up, the odds of getting colorectal cancer go down. Current thinking is that blood levels of vitamin D should be over 40 ng/mL. For most people, it takes a daily dose of between 1,000 to 2,000 IU to maintain these levels. These numbers are consistent with those seen in studies on prostate cancer and breast cancer. Adequate vitamin D, lowers risk of getting cancer significantly.


One would think that making sure that everyone has adequate vitamin D levels would be a no brainer. Vitamin D is inexpensive. Especially when compared to treating cancer.




Gorham et al. Optimal Vitamin D status for Colorectal Cancer Prevention: A quantitative Meta Analysis. American Journal of Preventive Medicine 2007;32(3)

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