Walking on sunshine – vitamin D and breast cancer

95% of the patients I test in my practice are deficient in vitamin D! This is not what we would expect, given the amount of daily sunshine we get exposed to in this part of the world. However, we have all been warned of the risk of getting malignant melanoma from too much UV sun exposure. So, we cover up and apply sunblock, or just stay out of the sun.

Also known as the sunshine vitamin, vitamin D is produced by our own bodies when our skins are exposed to sunlight. Unfortunately, the darker our skins (because of more melanin pigment), the lower our body’s ability to manufacture its own vitamin D.

Vitamin D also occurs naturally in certain foods that we eat. Below is a list:

  • Fish and fish oils:Tuna; Mackeral; Salmon; Cod Liver
  • Egg yolks
  • Cheese
  • Beef Liver
  • Fortified Foods: Soy Milk; Cereal; Calciferol; Vitamin D3

Thus, people who stay out of the sun, have darker skins, or have a mainly vegan diet are more likely to be deficient in vitamin D.

Once vitamin D is absorbed from our food or made by our skin, our kidneys convert it into its active form. Only in this form can it perform its full function.

Its oldest known and proven role is to allow our bodies to absorb calcium and in doing so, promote healthy bone growth in both children and adults. Newer, more recent research is showing that vitamin D may also be important in preventing and treating a number of serious, long-term health problems.

A lack of vitamin D is definitely responsible for rickets in children and osteoporosis in adults. It has also been linked to conditions like asthma, type 2 diabetes, high blood pressure, depression, multiple sclerosis, and Crohn’s Disease.

Many studies show a link between low vitamin D levels and breast cancer: WOMEN WHO HAVE BREAST CANCER TEND TO HAVE LOW VITAMIN D LEVELS.

In addition, with breast cancer, low levels of vitamin D are associated with worse outcomes, like bigger tumours, higher risk of cancer spreading and higher death rates. In a recent publication, looking at 77 studies, higher vitamin D levels were associated with a lower death rate in breast cancer patients. In fact, one study in particular, showed that breast cancer patients with the highest vitamin levels had a 44% lower death rate compared to patients with low levels.

Currently scientists think that optimum levels should be about 40-50 nanogram/millilitre (ng/ml) as measured by a blood test. The test measures 25 OH (hydroxy) vitamin D, which gives the best indication of our body’s vitamin D status.

If your levels are low, you can try to increase your levels by:

  •  Getting more sunshine without sunblock at the time of the day when your shadow is shorter than you are. Start with 15min then work up to 30 min of daily sunshine.
  • Increasing vitamin D containing foods in your diet. Remember good food sources are better than any pill you can swallow.
  • Taking supplements. Vitamin D toxicity is rare. Use 1000-5000 IU of vitamin D3 daily or calciferol, which is 50 000 IU once or twice a week available only by prescription from your doctor.

So, if you are currently being treated for breast cancer or you are a breast cancer survivor, speak to your doctors about testing your vitamin D levels and intervening where necessary.

How does all this information apply to the average healthy woman without breast cancer?

Certainly, from randomised controlled trials, in postmenopausal women receiving vitamin D with calcium supplementation versus calcium supplementation alone, there was a 77% reduction in all cancers including breast cancer between the first and fourth year of the trial, while those receiving calcium only had a 44% reduction. Whether this benefit can be extrapolated to pre-menopausal women, we simply don’t know. For me, it would make sense, even in premenopausal women to test levels and take steps to increase vitamin D to optimal levels. Until evidence exists to the contrary, what do we have to lose?


Dr Sumayya Ebrahim is a gynaecologist in private practice in Johannesburg. She is also a blogger. Check out her blog “vaginations by Dr E” on www.vaginations.co.za

Leave a Reply

Your email address will not be published. Required fields are marked *