Scientific evidence that vitamin D can help lower the risk of cancer development, as well as the risk of metastasis or recurrence, has been mixed. But several new studies point toward such a connection for certain cancers.
Numerous population-tracking studies over the years have shown that higher intake or blood levels of vitamin D are associated with a reduced risk of colorectal cancer. But a trial led by the Women’s Health Initiative found that women who take vitamin D and calcium supplements did not have a reduced incidence of colorectal cancer, according the National Cancer Institute. “Taken together, the available data are not comprehensive enough to establish whether taking vitamin D can prevent cancer,” the website states.
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Some new research is strengthening the case for vitamin D’s role in metastasis prevention. A preliminary study in mice by investigators at Stanford University indicated that breast cancer cells metastasize, or spread, more readily when the animals had low levels of the vitamin.
Early in 2015, Dana-Farber’s Kimmie Ng, MD, MPH, and her colleagues reported that clinical trial patients with metastatic colorectal cancer who had high levels of vitamin D in their bloodstream prior to treatment with chemotherapy and targeted drugs survived longer, on average, than those with lower levels of the vitamin.
Encouraging findings also came in a study published earlier this year by researchers at the University of California San Diego School of Medicine. They reported that higher levels of vitamin D – specifically serum 25-hydroxyvitamin D 25(OH)D – are associated with a correspondingly reduced risk of cancer. By pooling the results of two earlier studies, the researchers found that the age-adjusted cancer incidence was 1,020 cases per 100,000 person-years in patients in one of the studies and 722 per 100,000 person-years in the other cohort. Cancer incidence declined with increased 25(OH)D. Women with 25(OH)D concentrations of 40 nanograms/milliliter (ng/ml) or greater had a 67 percent lower risk of cancer than women with levels of 20 ng/ml or less.
The evidence that UVB and vitamin D can reduce risk and increase survival of cancer is strong for many types of cancer.
Even the Women’s Health Initiative showed that 400 IU/d vitamin D3 + 1500 mg/d calcium reduced the risk of cancer by 15-20% for those not taking those supplements prior to entry [Bolland, 2011]. Higher 25-hydroxyvitamin D [25(OH)D] concentrations were associated with better 9-year survival for breast, colon, lung cancer and lymphoma [Tretli, 2012]
Breast cancer incidence is significantly inversely correlated with 25(OH)D concentration from case-control studies [Grant, 2015].
For a review of the evidence that UVB and vitamin D reduce cancer risk, see [Grant, 2016].
Optimal 25(OH)D concentration for cancer risk reduction is >40 ng/mL (100 nmol/L), which takes 1000-4000 IU/d vitamin D3.
Bolland MJ, Grey A, Gamble GD, Reid IR. Calcium and vitamin D supplements and health outcomes: a reanalysis of the Women’s Health Initiative (WHI) limited-access data set. Am J Clin Nutr. 2011 Oct;94(4):1144-9.
Grant WB. 25-Hydroxyvitamin D and breast cancer, colorectal cancer, and colorectal adenomas: case–control versus nested case–control studies, Anticancer Res. 2015;35(2):1153-60.
Grant WB. Roles of Solar UVB and Vitamin D in Reducing Cancer Risk and Increasing Survival, Anticancer Res. 2016;36(3):1357-1370.
Tretli S, Schwartz GG, Torjesen PA, Robsahm TE. Serum levels of 25-hydroxyvitamin D and survival in Norwegian patients with cancer of breast, colon, lung, and lymphoma: a population-based study. Cancer Causes Control. 2012;23(2):363-70.
I am 71 years old. I take 50,000 IUs of Vitamin D3 per month. I have CHF, hypothyroidism, osteoarthritis, RA, and I’m constantly having to deal with bouts with anemia. Is 50,000 IUs of Vitamin D per month enough for me?