Breast Cancer Prevention: Canadian Cancer Society Recommends Vitamin D3 to Reduce
Breast Cancer Risk
By Keith D. Bishop, Clinical Nutritionist, B.Sc. Pharmacy - June 2007
The Canadian Cancer Society recommends taking vitamin D3 during the fall and
winter to reduce the risk for colorectal cancer, breast cancer and prostate cancer.
Research studies demonstrate people with lower vitamin D3 levels have a greater risk of developing cancer.
Supplemental vitamin D3 seems to reduce cancer risk.
In consultation with a health care provider the cancer society recommends
Adults living in Canada should consider taking 1,000 international units (IU) of vitamin D3 supplements a day in
the fall and winter, when sun exposure in the country is not high enough to produce adequate vitamin D
Adults at higher risk of having vitamin D3 deficiency should consider taking the 1,000 IU supplement year
Factors that increase the risk for vitamin D3 deficiency include:
The Canadian Cancer Society recommends 1,000 IU daily of vitamin D3. Even this low level of
supplementation will lower the risk cancer.
- Getting older, since the skin is less capable of producing vitamin D3 from exposure to the sun with age. No
precise age cutoff has been determined.
- Darker skin, since the darker pigment acts as a natural sunscreen that makes it harder to produce the
- Not going outside often.
- Wearing clothing that covers most skin.
In June of 2007 the American Journal of Clinical Nutrition published a vitamin D3 and calcium study of
1,200 women in Eastern Nebraska. There were about 37 cases of breast cancer in 1,000 women. When vitamin D3 and
calcium were given, the risk of cancer was reduced by about half, to 18 cancers per 1,000 women, compared to
Researchers state: “Improving calcium and vitamin D nutritional status substantially reduces all-cancer
risk in postmenopausal women.”
 CBC News June 7, 2007
 Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Lappe JM,
Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. American Journal of Clinical Nutrition 2007
Natural Cancer Reports Pearl
A daily dose of 1,000 iu of vitamin D3 may not be enough. Additional studies show more than half of the
U.S. population is deficient in vitamin D3. A 25-hydroxyvitamin D3 blood test is the only way to know how much
vitamin D3 you should be taking.
A word of caution: The prescription capsule form of vitamin D is not the natural form of vitamin D3. It is
vitamin D2 and is about ¼ to ½ as strong as the natural vitamin D3 called cholecalciferol.
Vitamin D3 appears to help cell recognize what kind of cell they should become or when they should stop
Sunshine exposure and fatty fish and egg yolks are the only natural sources of vitamin D3.
Alternative Breast Cancer Treatment Strategies
Return from Breast Cancer Natural Prevention: Canadian Cancer Society
Recommends Vitamin D3 to Reduce Breast Cancer Risk to 2007 Natural Cancer News