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Vitamin D

Vitamin D is needed to help absorb calcium and phosphorus which are essential for bone health.  It can also improve muscle strength and immune function.  It helps to reduce inflammation.  We need to test our level of vitamin D, via a blood test, to ensure that it is not deficient – especially in Australia where we are advised to cover our skin when outdoors so as to avoid skin cancer.

There is also evidence that low levels of vitamin D can be a causal factor in the development of some cancers – adequate vitamin D levels slow the growth of abnormal cells.  Research has also shown that the lower the level of vitamin D, the more aggressive is the prostate cancer (https://www.harvardprostateknowledge.org/low-vitamin-d-tied-aggressive-prostate-cancer).

A 2014 study, “Vitamin D Deficiency Predicts Prostate Biopsy Outcomes” by Adam B. Murphy, Yaw Nyame, Iman K. Martin, et al. (Clin Cancer Res 2014;20:2289-2299), concluded that in African American men, vitamin D deficiency was associated with increased odds of prostate cancer diagnosis on biopsy. In both European American and African American men, severe deficiency was positively associated with higher Gleason grade and tumour stage.

Men with dark skin absorb less ultraviolet light from the sun than men of a lighter complexion, and so tend to make less vitamin D.

I had read about Vitamin D, skin cancer, cholesterol, and prostate cancer in a wonderful 2007 book, “Survival of the sickest” by Dr. Sharon Moalem.   Our skin converts cholesterol to vitamin D when we are exposed to ultraviolet B in sunlight.  Australia’s “Slip-Slop-Slap” anti-skin cancer campaign succeeded in reducing sun exposure and it seems that vitamin D deficiencies rose.  He mentions a growing belief that vitamin D inhibits the growth of cancer cells in the prostate.

Blood tests have revealed my level of vitamin D to be slightly deficient before and after my diagnosis.  I now aim to take 2,000 IU per day.

It seems that exposure to sunlight is important for prevention and containment of prostate cancer and is a factor in keeping the level of cholesterol down – through the action of converting cholesterol into vitamin D.

There is evidence that high-dose vitamin D can prevent progression of prostate cancer for men on active surveillance (the safety of high-doses needs to be confirmed).  Researchers at Macquarie University and Cancer Council NSW are conducting a trial to evaluate the benefits and risks (Prostate News January 19, published by the Prostate Cancer Foundation of Australia).

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What causes prostate cancer?

In 2010, when I had my first PSA test with a reading of 20, the urologist I was referred to found no irregularity in the rectal examination.  I asked him whether there was anything I could do with regard to diet that would limit risk of developing prostate cancer or lower the risk of any prostate cancer advancing.  He said “No”.  I found this disappointing and it seems that we now know more than he did at that time. 

According to the Australian government prostate cancer website (https://prostate-cancer.canceraustralia.gov.au/home):

Factors that are associated with a higher risk of developing prostate cancer include:

  • age: the risk of developing prostate cancer increases rapidly from age 50
  • family history: men who have a father or brother with prostate cancer are more likely to develop it themselves
  • changes in certain genes that can be carried in families: mutations in the BRCA1 or BRCA2 genes may increase the risk of developing prostate cancer in some men. People with a genetic condition called Lynch syndrome (also called hereditary nonpolyposis colorectal cancer or HNPCC) also have a higher risk of developing prostate cancer.

This is no doubt true, but does not inform men about what they can do to minimise the risk of developing prostate cancer.  The website only provides generic suggestions such as don’t smoke, be sun smart, eat a balanced and nutritious diet, and exercise – none of which are necessarily specific to prostate cancer.

There is a major gap in knowledge here and future posts will delve more deeply into specific causes.  It is an area where more research is urgently needed.

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Saturated fats increase the likelihood of aggressive prostate cancer

Men who eat more saturated fats are at greater risk of developing aggressive prostate cancer than those with a healthier diet (AFR 7 February 2019).

Fatty acids are taken up into prostate cancer cells, increasing tumour growth.

Researchers at Monash Biomedicine Discovery Institute and University of Melbourne Physiology Department showed that blocking the uptake of fatty acids could slow the prostate cancer’s growth.

Given that prostate cancer has developed in some men and not yet been diagnosed, this is another good reason for men to reduce consumption of saturated fats.  Saturated fats raise blood cholesterol levels and so can increase the risk of heart disease and stroke.

Foods high in saturated fats include beef, lamb, pork, chicken skin, butter, cheese, milk, cream, palm oil, and coconut oil.