Is Vitamin D the Anti-Cancer Vitamin?

30 Apr

By Elizabeth Miler

Elizabeth Miller-Sun Photo

Photo Courtesy of Elizabeth Miller

According to current research, Vitamin D may play a role in reducing cancer risk and mortality. Biologically sourced from sunlight’s Ultraviolet B rays, Vitamin D has notoriously been recommended by health experts for its role in bone health. As ultraviolet rays from the sun are known to be a leading cause of skin cancer, other sources of Vitamin D from fortified foods and supplements are often favored for prevention of osteoporosis. More recently, epidemiological and clinical research has demonstrated that sufficient levels of Vitamin D (from the diet, sun or a supplement) may also be associated with decreased risk of some forms of cancer.

As many theories in science often begin, the association between Vitamin D and cancer was first discovered as a population-based geographical trend back in 1980.  Researchers at John Hopkins University observed variances in colorectal cancer incidence that correlated with geographical location throughout the United States (Garland and Garland, 1980). Regions with increased sunlight exposure like New Mexico and Arizona had lower colorectal cancer rates than cooler, less sunny climates such as New York and New Hampshire. This observation motivated further research to identify an association between Ultraviolet-B light and other types of cancer, and strikingly, increased sunlight was associated with lower rates of 15 other cancers (Grant and Garland, 2006). Multiple meta-analyses have demonstrated an association of higher Vitamin D levels and increased survival rates of patients with colorectal, hematological and breast cancer (Mohr et al., 2015; Malmi et al., 2014; Vaughan-Shaw et al., 2017). Patients with the highest blood levels of the biologically active form of Vitamin D, known as 25-hydroxyvitamin D, had the lowest risk of cancer mortality (Wang et al., 2014; Vaughan-Shaw et al., 2017).

Despite these interesting findings, these observational studies can only provide circumstantial evidence of the correlation between Vitamin D and cancer risk, and cannot confirm a cause and effect relationship. For example, perhaps these positive associations of decreased cancer risk and mortality with sunlight exposure can be explained by other factors, such as increased exercise outdoors during warmer weather, or increased fruit and vegetable consumption. In order to truly identify if Vitamin D levels have an effect on cancer incidence and mortality, randomized controlled trials in humans need to be conducted involving the supplementation of Vitamin D.

To date, only a few clinical trials have demonstrated a reduction in cancer risk with supplementation of Vitamin D. A 2014 meta-analysis examined four randomized controlled trials involving Vitamin D supplementation with doses of 400-1100 IU/day, for duration of 2-7 years (Keum and Giovannucci, 2014). The results of this meta-analysis did not observe any significant effects on overall cancer incidence, yet did see a consistent 12% reduction in overall cancer mortality in all four studies (Keum and Giovannucci, 2014). The authors stated that the positive results in overall cancer mortality could have been related to Vitamin D’s role in altering specific cancer processes such as metastasis, apoptosis, and cell proliferation. These mechanisms concur with other observations from cell culture and animal based models, demonstrating the anti-cancer role of Vitamin D (Moukayed and Grant, 2017). It is still unclear if Vitamin D only has anti-carcinogenic effects in populations with cancer or if it can also prevent it in healthy individuals. Further research is required to understand the complex relationship between the sunshine vitamin and cancer prevention, but the evidence seems promising.

As we await the results of more randomized controlled trials, we should not discount the importance of Vitamin D in the diet, as this vitamin is essential to bone health. For those not lucky enough to live close to the equator, it is recommended that individuals deficient in Vitamin D fortify their diet with a supplement, or consume fortified foods such as dairy and nut milks. Health Canada recommends that individuals aged 1-70 consume 600 IU of Vitamin D per day, which can easily be reached with either fortified foods, a supplement, or sitting in the sun for about 15 minutes (Health Canada, 2012). Luckily we are finally reaching the end to the dreary dark days of winter, so next time you see the sun shining, go outside and reap the benefits from the ball of life in the sky.


Garland, C. F., & Garland, F. C. (1980). Do sunlight and vitamin D reduce the likelihood of colon cancer? International Journal of Epidemiology, 9(3), 227-231. doi:10.1093/ije/9.3.227

Giovannucci, E., Liu, Y., Rimm, E. B., Hollis, B. W., Fuchs, C. S., Stampfer, M. J., & Willett, W. C. (2006). Prospective study of predictors of vitamin D status and cancer incidence and mortality in men. Journal of the National Cancer Institute, 98(7), 451–459. Retrieved from:

Grant, W. B., & Garland, C. F. (2006). The association of solar ultraviolet B (UVB) with reducing risk of cancer: multifactorial ecologic analysis of geographic variation in age-adjusted cancer mortality rates. Anticancer Research, 26, 2687-2700. Retrieved from:

Health Canada (2012). Vitamin D and calcium updated dietary reference intakes. Retrieved from:

Keum, N., & Giovannucci, E. (2014). Vitamin D supplements and cancer incidence and mortality: a meta-analysis. British Journal of Cancer, 2014(111), 976-980. doi: 10.1038/bjc.2014.294

Maalmi, H., Ordóñez-Mena, J. M., Schöttker, B., & Brenner, H. (2014). Serum 25-hydroxyvitamin D levels and survival in colorectal and breast cancer patients: Systematic review and meta-analysis of prospective cohort studies. European Journal of Cancer, 50(8), 1510-1521. doi:10.1016/j.ejca.2014.02.006

Mohr, S. B., Gorham, E. D., Kim, J., Hofflich, H., Cuomo, R., E., & Garland, C., F. (2015). Could vitamin D sufficiency improve the survival of colorectal cancer patients? Journal of Steroid Biochemistry & Molecular Biology, 148(2015), 239-244. doi: 10.1016/j.jsbmb.2014.12.010

Moukayed, M., & Grant, W. B. (2017). The roles of UVB and vitamin D in reducing risk of cancer incidence and mortality: A review of the epidemiology, clinical trials, and mechanisms. Reviews in Endocrine and Metabolic Disorders, 1-16. doi:10.1007/s11154-017-9415-2

Vaughan-Shaw, P. G., O’Sullivan, F., Farrington, S. M., Theodoratou, E., Campbell, H., Dunlop, M. G., & Zgaga, L. (2017). The impact of vitamin D pathway genetic variation and circulating 25-hydroxyvitamin D on cancer outcome: systematic review and meta-analysis. British Journal of Cancer, 116, 1092–1110. doi:10.1038/bjc.2017.44

Wang, B., Jing, Z., Li, C., Xu, S., & Wang, Y. (2014). Blood 25-hydroxyvitamin D levels and overall mortality in patients with colorectal cancer: A dose–response meta-analysis. European Journal of Cancer, 50(12), 2173-2175. doi:10.1016/j.ejca.2014.05.004




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