Breast cancerPrevention

 Most, but not all, studies indicate high levels of vitamin D are associated with a lower risk of breast cancer. 

A cohort study followed women for an average of 10 years of follow-up, during which time 276 premenopausal and 743 postmenopausal women had a confirmed diagnosis of incident invasive breast cancer. Higher intakes of total calcium and vitamin D were moderately associated with a lower risk of premenopausal breast cancer; the hazard ratios in the group with the highest relative to the lowest quintile of intake were 0.61 (95% confidence interval, 0.40-0.92) for calcium (P = 0.04 for trend) and 0.65 (95% confidence interval, 0.42-1.00) for vitamin D intake (P = 0.07 for trend).

The inverse association with both nutrients was also present for large or poorly differentiated breast tumors among premenopausal women (P< or = 0.04 for trend). By contrast, intakes of both nutrients were not inversely associated with the risk of breast cancer among postmenopausal women1.  

An earlier study with the same cohort found for total vitamin D (>500 IU/day versus <or=150 IU/day; the relative risk of developing breast cancer = 0.72, 95% CI = 0.55 to 0.94)2. There was also a nearly-significant inverse correlation with respect to calcium intake: OR = 0.89 (95% CI, 0.78-1.01). A recent case-control study in Canada found that vitamin D supplement intake 400 IU/d compared with no intake was associated with a reduced risk of breast cancer (adjusted OR: 0.76; 95% CI: 0.59, 0.98)3.

A meta-analysis in the literature used data from eleven studies on vitamin D intake, seven studies on circulating 25(OH)D levels, and 15 studies on calcium intake and breast cancer risk. From the meta-analysis, there was a significant inverse relationship between the highest quantile of circulating 25(OH)D compared to the lowest quantile: OR = 0.55, (95% CI = 0.38-0.80)4

There has been one randomized controlled trial with post-menopausal women living in Nebraska using 1450 mg/day of calcium and, for some, 1100 IU/day of vitamin D, that found a 77% reduced risk of all-cancer incidence between the ends of the first and fourth years5. However, it did not have enough participants to study breast cancer in particular.

Based on the observational and ecological studies and the randomized controlled trial, it appears that keeping serum 25(OH)D levels above 40 ng/mL (100 nmol/L) might reduce the risk of breast cancer compared to levels below 30 ng/mL (75 nmol/L).

Page last edited: 07 September 2011

References

  1. Lin, J. Manson, J. E. Lee, I. M. Cook, N. R. Buring, J. E. Zhang, S. M. Intakes of calcium and vitamin D and breast cancer risk in women. Arch Intern Med. 2007 May 28; 167 (10): 1050-9.
  2. Shin, M. H. Holmes, M. D. Hankinson, S. E. Wu, K. Colditz, G. A. Willett, W. C. Intake of dairy products, calcium, and vitamin d and risk of breast cancer. J Natl Cancer Inst. 2002 Sep 4; 94 (17): 1301-11.
  3. Anderson, L. N. Cotterchio, M. Vieth, R. Knight, J. A. Vitamin D and calcium intakes and breast cancer risk in pre- and postmenopausal women. Am J Clin Nutr. 2010 Jun; 91 (6): 1699-707.
  4. Chen, P. Hu, P. Xie, D. Qin, Y. Wang, F. Wang, H. Meta-analysis of vitamin D, calcium and the prevention of breast cancer. Breast Cancer Res Treat. 2010 Jun; 121 (2): 469-77.
  5. Lappe, J. M. Travers-Gustafson, D. Davies, K. M. Recker, R. R. Heaney, R. P. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr. 2007 Jun; 85 (6): 1586-91.