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Meta-analysis: Vitamin D supplementation reduces total cancer mortality

Posted on: July 2, 2014   by  Amber Tovey


A new analysis of randomized controlled trials, published in the British Journal of Cancer, has found that vitamin D supplementation may reduce total cancer mortality, but had no effect on total incidence of cancer.

Through various research, vitamin D levels have been shown to affect cancer. Animal studies have shown that the active form of vitamin D, calcitriol, helps reduce tumor growth and development. Over 15 types of cancer have been associated with low sun exposure, such as breast cancer and colorectal cancer.

Despite these proposed links between vitamin D and various cancers, most trials haven’t found consistent results regarding vitamin D supplementation and cancer incidence or mortality. This is because the randomized controlled trials (RCTs) looking at vitamin D and cancer either didn’t have a strong design, or weren’t looking specifically at cancer mortality and incidence.

Recently, Dr. Nana Keum and Dr. Edward Giovannucci conducted a meta-analysis of RCTs to help determine how vitamin D supplementation affects total cancer mortality and incidence.

The researchers only included RCTs that looked at cancer mortality and incidence. In total, they examined four randomized controlled trials on vitamin D supplementation and total cancer incidence, and three randomized controlled trials on vitamin D supplementation and total cancer mortality.

The length of the randomized controlled trials ranged from two to seven years, with vitamin D doses ranging from 400 to 1100 IU per day.

Their analysis showed the following:

  • Vitamin D supplementation had no significant effect on total cancer incidence.
  • Vitamin D supplementation significantly reduced total cancer mortality by 12%.

It is important to note that all of the studies but one included calcium as part of their intervention. Since the sample population was replete with calcium, the effect of vitamin D on individuals with low levels of calcium was not determined.

The researchers summarized the implications of their findings,

“In the UK, approximately 159,000 people die of cancer annually, so a 15% reduction would result in a substantial number of potentially preventable deaths from cancer.”

While the results provides substantial evidence that vitamin D supplementation may help reduce total cancer mortality, further randomized controlled trials using adequate dosage should be conducted with total cancer mortality and total cancer incidence as their primary outcomes.


Keum, N & Giovanucci, E. Vitamin D Supplements and Cancer Incidence and Mortality: a Meta-Analysis. British Journal of Cancer, 2014.

3 Responses to Meta-analysis: Vitamin D supplementation reduces total cancer mortality

  1. mbuck

    Clearly, 400 to 1100 IU per day, is simply not enough to show meaningful changes. Previous studies have shown that when 25(OH)D levels begin at 32 ng/ml and climb higher (50-70 ng/ml), that this is when positive associations are seen. Please see Dr. Cedric Garland of UCSD’s youtube video on “How Vitamin D Reduces Incidence of Cancer: DINOMIT Model” at:


  2. [email protected]

    Do I need vitamin K2 to keep my arteries free of calcium? And I take 8,000 IU daily and keep my BP normal.

  3. Rita and Misty

    Correcting my vitamin D deficiency balanced my hormones, but this positive effect only occurred once my 25(OH)D level was raised to 74 ng/ml.

    It is true that K2 helps to keep calcium out of our arteries and actually directs it to our bones.

    See Mercola: http://articles.mercola.com/sites/articles/archive/2013/10/19/vitamin-d-vitamin-k2.aspx

    I also consider Boron, Iodine, Selenium, Zinc and Magnesium to be co-factors of D.

    However, I’m not a healthcare professional. I’m just someone who cares about health.


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