Researchers from Harvard have shown that higher intakes of calcium and vitamin D may reduce the risk of developing premenopausal breast cancer.[1] The details of this study appeared in the May 28, 2007 issue of the Archives of Internal Medicine. In a separate report published in the June 2007 issue of TheAmerican Journal of Clinical Nutrition, researchers from Creighton University reported that supplementation with vitamin D and calcium reduces the risk of cancer.[2]  

There is increasing evidence that higher intakes or increased levels of vitamin D are associated with a decreased risk of several types of cancer. The current data suggests that doses of 1-2000 IU/day are necessary for this preventative effect.  

The Harvard study evaluated total calcium and vitamin D intake in over 10,000 premenopausal and 20,000 postmenopausal women who were free of cancer at the beginning of the study. The average duration of study was 10 years. These authors reported that the risk of developing premenopausal breast cancer was 40% less in women with the highest compared to the lowest intake of vitamin D. They also reported a lower incidence of large and aggressive cancers in women with the highest intake of vitamin D and calcium. This relationship was not observed in post-menopausal women.  

The study from Creighton University randomly allocated 1,179 women >55 years of age to receive 1400-1500 mg of calcium, the same dose of calcium plus 1100 IU/day of vitamin D3 or placebo. They reported that after the first 12 months, the risk of developing any cancer fell by 77% for the calcium plus vitamin D group but not for the calcium alone group compared to placebo. These researchers concluded that the risk of cancer was significantly reduced by vitamin D and calcium supplementation.  

Comments: The data from Harvard is consistent with a previous study from the Women’s Health Initiative presented at the 2006 annual meeting of the American Society of Clinical Oncology (ASCO) where calcium plus vitamin D supplements did not reduce the risk of breast cancer in postmenopausal women. The observation that vitamin D can reduce the risk of developing premenopausal breast cancer is of major interest. The Creighton University study is one of the few randomized trials to show an effect of vitamin D supplementation on reducing the risk of cancer.  

Related News:  

1-2000 IU/Day of Vitamin D Recommended for Prevention of Colorectal Cancer (03/09/2007)

Increased Vitamin D Intake Reduces Risk of Pancreatic Cancer (09/20/2006)

Breast Cancer Risk Not Reduced by Calcium Plus Vitamin D (06/13/2006)

Role of Vitamin D in Breast Cancer Prevention Explored at 97th AACR Meeting (05/02/2006)

Higher Levels of Vitamin D May Protect Against Cancer in Men (04/07/2006)

Calcium and Vitamin D Supplementation May Not Prevent Colorectal Cancer (03/06/2006)

Reports Emphasize Importance of Relatively Large Doses of Vitamin D for Cancer Prevention (01/09/2006)