Vitamin D and prostate cancer

A wonder drug?

There’s been a lot of buzz about the benefits of vitamin D, particularly in the prevention of prostate, colon, and breast cancers.

We know that as men get older, the incidence of prostate cancer rises.  Studies have shown that older people have lower levels of this important vitamin.

The evidence is mixed

  • Most recently, a small study of 37 men showed that vitamin D may help slow or prevent low-grade prostate cancer.  Men took 4,000 IUs a day before having surgery for prostate cancer.  After surgery, researchers found  improvements in their tumors.
  • Marshall et al, however, demonstrated in a small study that there were no significant changes in PSA in 52 men with low risk prostate cancer who took 4,000 IU/daily for one year.
  • In another study, Barnett et al concluded that there was no association between serum 25-OH vitamin D levels, and the subsequent risk of prostate cancer.  This was a study of 1,433 men who were older or equal to age 65, and did not have a history of prostate cancer. 
  • In a large meta analysis, Gilbert et al determined that there was little evidence to support a major role of vitamin D in preventing prostate cancer or its progression.

Other studies

Gupta et all did an extensive search to identify all the epidemiological studies on the relationship between this vitamin and prostate cancer.

The challenge with epidemiological studies is that they can only show that a factor is associated with an outcome in men with prostate cancer. They cannot prove a definite cause of the outcome. 

But here's what they found:

  • Results of studies were mostly conflicting or negative about the benefits of getting this vitamin from food
  • In one study, men who took supplements (greater than 600 IU daily) had less of a risk of prostate cancer (40% reduction). However, nine other studies did not prove a protective factor. The study authors suggested that perhaps the levels taken need to be higher to really determine the benefits
  • Of ten studies reviewed, most showed that exposure to sunlight may offer a protective factor against prostate cancer
  • Results were conflicting in seven studies that were conducted to determine if having a vitamin D deficiency increases a man’s risk for prostate cancer
  • Kristal et al reported that neither dietary nor supplemental intakes of nutrients often suggested for prostate cancer prevention, including this vitamin, were significantly associated with cancer risk.

How to get it

You can get your daily “D” in several ways:

  • By eating foods like fish, eggs, and fortified dairy products (although the amounts are small)
  • By taking supplements
  • By sitting in the sun (but you’ve got to be careful about skin cancer)

Back to prostate cancer and nutrition

References:

Vitamin D might slow prostate cancer.  Web MD.  Accessed April 18, 2015.

Barnett CM, Nielson CM, Shannon J, et al. Serum 25-OH vitamin D levels and risk of developing prostate cancer in older men. Cancer Causes Control. 2010;21(8):1297-303. Epub 2010 Apr 10.

Gilbert R, Martin RM, Beynon R, et al. Associations of circulating and dietary vitamin D with prostate cancer risk: a systematic review and dose-response meta-analysis. Cancer Causes Control. 2011;22(3):319-40. Epub 2011 Jan 4.

Gupta D et al. Prostate Cancer Prostatic Dis. 2009 Apr 7. [Epub ahead of print]

Kristal A, Arnold K, Neuhouser M, et al. Diet, Supplement Use, and Prostate Cancer Risk: Results From the Prostate Cancer Prevention Trial. Am. J. Epidemiol. 2010;172(5):566-577.

Always consult a medical professional.

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