There have been several studies into the link between breast cancer survival and the ‘sunshine vitamin’ (vitamin D). 

Although it is too early to refer to vitamin D as a new weapon in our armamentarium, the association has created a lot of interest and indeed may lead to important new discoveries in the future. The results of these studies are worth exploring.

Published earlier this year in the Anticancer Research Journal is a study by the University of California’s San Diego School of Medicine (led by Prof Cedric Garland), which showed that breast cancer patients with optimal levels of 25-hydroxyvitamin D (30 nanograms per milliliter) in their blood had an approximate 50% lower fatality rate.

This study was inspired by a 2011 study conducted by Prof Garland that showed that low vitamin D levels were linked to a high risk of premenopausal breast cancer.  It was these findings that prompted Prof Garland to question the link between vitamin D and breast cancer.

Communication between cells

He believes that the reason vitamin D decreases the fatality rate of breast cancer patients is that it increases the communication between cells by activating a protein that stops aggressive cell division.  His thinking is that vitamin D receptors prevent tumour growth by not allowing the tumour’s blood supply to expand.

The 2014 study followed 4 443 breast cancer patients for an average of nine years.  It divided the women into groups – those with ‘high’ levels of 25-hydroxyvitamin D were recorded as 30ng/ml while the lower levels were listed as around 17ng/ml.

While Prof Garland has recommended that clinical trials are conducted to confirm the findings, he has taken the fairly conclusive route of suggesting that doctors consider adding vitamin D into the monitored treatment regime of breast cancer patients.  As he says, 30ng/ml has already been proven to be safe so there is no reason not to include the vitamin into treatment plans already.

Vitamin levels and cancer deaths

Not specifically linked to breast cancer, another study entitled Vitamin D and mortality (a meta-analysis of individual participant data from a large consortium of cohort studies from Europe and the US) shows that death (from any cause) among older previous cancer patients who were on the lower spectrum of 25-hydroxyvitamin D was over 1.5 times higher.

This study used data from 26 018 participants between the ages of 50 and 79 that were followed for 16 years.  In that time 6 695 deaths occurred, 2 227 were cancer related.  The team found a definite link between those with lowest vitamin D levels and the cancer deaths – specifically with people who had a history of the disease.

Although they acknowledge that the results could be somewhat skewed because the study was conducted on an older group of cancer patients and they are still waiting for further results to guide them in term of what vitamin D supplementation should be recommended, it is becoming increasingly clear that vitamin D may have an important part to play in the fight against cancer.

So what exactly is vitamin D?

Vitamin D is essential to the healthy function of our bodies.  It helps to regulate the absorption of calcium in our bones, strengthens the immune system and aids in cell communication (as mentioned earlier).  It is a fat-soluble vitamin, which comes in five forms, D1, D2, D3, D4 and D5.

Vitamin D2 and D3 are the most important for our bodies, and Vitamin D3 is what we get from natural exposure to the sun.  It’s important to note however that just getting your dose from sun exposure can be complicated and unreliable but relying just on diet is also tricky – as the Vitamin D Council in the US says.   So the best option is a combination of the two.

A simple blood test will give you an accurate understanding of what your patient’s vitamin D levels are like.  And when you get the results, make sure you prescribe a supplement with an optimal level not just a normal one (optimal is between 32 and 100 ng/ml).

Vitamin D is known as the sunshine vitamin and is the only vitamin the human body can produce itself, which it does when the skin is exposed to the sun.  Living in sunny SA, we don’t often supplement for vitamin D, but if a patient’s blood test shows his/she is sitting on the low end of the spectrum it may be worth including a vitamin D3 supplement in his/her daily routine.

Some patients may need to be tested twice a year, once in Summer and once in Winter to most effectively manage levels. Foods that contain vitamin D are fatty fish, beef liver, egg yolks and fortified foods like certain cereals and drinks.

Author: Prof Justus Apffelstaedt, Head of the Breast Clinic, Tygerberg Hospital and Stellenbosch University

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