Vitamin D reduces breast cancer risk

How much vitamin D do you need to reduce breast cancer risk?

It has been recognized for over a decade that vitamin D has a protective effect against a variety of cancers, including breast cancer (Garland et al., 2006; Krishnan et al., 2010). But new research from our friends at GrassrootsHealth on vitamin D and breast cancer has me really excited. The group has found that maintaining a higher vitamin D level can reduce breast cancer risk by — are you ready for it? — a whopping 80 percent.

Higher vitamin D levels reduce breast cancer risk AND reduce bone loss

GrassrootsHealth recently combined two randomized clinical trials from Dr. Joan Lappe (Lappe et al., 2007; McDonnell et al, 2016) looking at women over four years. What they found was that was that those women who had vitamin D blood levels equal or greater then 60 ng/mL — the same levels helpful in preventing bone loss — had an 80% lower risk of breast cancer than women with concentrations less than 20 ng/mL (a very deficient level indeed).

Meanwhile, a similar study conducted recently showed that women with a vitamin D level above 38 ng/mL (about the level conventionally regarded as “adequate) had a 21% lower risk of breast cancer than women with levels at or below 24.6 (O’Brien et al., 2017).

You can’t help but notice the difference in risk reduction at 60 ng/mL versus 38 ng/mL is rather large. It reinforces what I’ve maintained all along — that current serum vitamin D recommendations are too low for women to get the best protective effects. But it also strongly supports the need for everyone to keep tabs on their vitamin D levels to ensure they don’t fall below the minimum level for bone health (and overall health).

Watch my interview with Carol Baggerly, the founder of GrassrootsHealth, to learn more about this groundbreaking research and Grassroots Heath’s new D-Action Cancer Prevention Society!


Garland CF, Garland FC, Gorham ED, Lipkin M, Newmark H, Mohr SB, Holick MF. The role of vitamin D in cancer prevention. Am J Public Health. 2006 February; 96(2): 252–261.

Krishnan AV, Trump DL, Johnson CS, Feldman D. The role of vitamin D in cancer prevention and treatment. Endocrinol Metab Clin North Am. 2010 Jun;39(2):401–418.

Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr. 2007 Jun;85(6):1586–1691.

McDonnell SL, Baggerly C, French CB, Baggerly LL, Garland CF, Gorham ED, Lappe JM, Heaney RP. Serum 25-hydroxyvitamin D concentrations ≥40 ng/ml are associated with >65% lower cancer risk: pooled analysis of randomized trial and prospective cohort study. PLoS One. 2016; 11(4): e0152441.

O’Brien KM, Sandler DP, Taylor JA, Weinberg CR. Serum vitamin D and risk of breast cancer within five years. Environ Health Perspect. 2017; DOI:10.1289/EHP943.

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