How Vitamin D Protects Against Cancer

  • 5 May 2010
  • Reading time 21 mins
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Find out the truth about vitamin D and how much you need, depending on where you live, to cut your cancer risk.

Halve your risk of colon cancer The vitamin D and cancer connection, first proposed by Dr Cedrick Garland in 1980, led to research that showed a strong association between risk of colon cancer and dietary intake of vitamin D and calcium. [2] An eight year study of 25,802 people from the state of Maryland in the USA found that those with blood levels of vitamin D equivalent to 10mcg (400iu) or more had half the risk of colon cancer compared to those with lower levels. [3] This is twice the US RDA of 5mcg (200iu).

In the UK, there is no recommended daily dietary intake for vitamin D if you are aged between four and 50 and live a ‘normal life-style’. However, ‘normal’ means spending time every day outdoors in the sunshine, which is not always possible given the UK weather and people’s lifestyles. For those confined indoors, experts recommend 10mcg per day. [4] Since 1980, many researchers have confirmed Dr Garland’s hypothesis. A scientific review undertaken by the National Cancer Institute in 2007 found that vitamin D was beneficial in preventing colorectal cancer. Although the study found no link between vitamin D status and overall cancer mortality, the study did show that blood levels of 80 nanomoles per litre (nmol/L) or higher were associated with a 72% reduction in colorectal cancer mortality. [5] As you’ll see later, to achieve blood levels of 80nmol/L, you need to have just over 25mcg (1,000iu) a day.

Similar blood levels and vitamin D intake were found to protect against colon cancer in a study that followed 1,500 people for 25 years. At 80nmol/L the rate was cut by 50%, whereas levels of over 100nmol/L reduced colon cancer incidence by 66%, according to research published in the American Journal of Preventative Medicine. When five studies were ‘pooled’ together, researchers found that a 50% lower risk of colorectal cancer was associated with a blood level of greater than, or equal to, 83nmol/L, compared to less than or equal to 30nmol/L. They concluded that 1,000-2,000iu per day of vitamin D could reduce the incidence of colorectal cancer with minimal risk. [6 The full content of this report is only viewable by 100% Health Club members.

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