Cancer. The very word is enough to strike fear into most of us.

We all, at the very least, know someone (or know of someone) directly affected by cancer. Some cancers can be actively prevented by, for example, choosing not to smoke, and others can be permanently cured with early detection and routine screening (including some breast, skin, and prostate cancers).

Preventing cancer wherever possible is essential, as many people will ultimately die from the disease.

For example, in Australia in 2022*:

  • Cancer is currently the leading cause of death.
  • It’s estimated that there will be 162,000 new cancer diagnoses by the end of 2022; non-melanoma skin cancer rates are much, much higher.
  • While cancer can occasionally occur in childhood, the odds of developing cancer increase with age, and 50% of Australians will be diagnosed with a form of cancer by age 85 (this includes non-melanoma skin cancers).
  • The most common cancers diagnosed in Australia (not including non-melanoma skin cancers) are prostate, breast, bowel, melanoma, and lung cancer.
  • 50,000 people will die from cancer in 2022; while the rate of cancer diagnoses has risen (to a large extent, due to an ageing population), the death rate has fallen by more than 24% in the last 40 years.
  • Average 5-year survival rates for all cancers combined are currently 70%; for some cancers, this exceeds 90%. Prevention, early detection, and prompt treatment are imperative.

(*Sources: Cancer Council; Australian Institute of Health & Welfare)

One thing that has been shown to possibly have a role in cancer prevention is Vitamin D.

What is Vitamin D?

Vitamin D is a nutrient the body generates when triggered to do so by sunlight hitting the skin. The body can’t make vitamin D on its own; without sunlight, it needs to be ingested in food or supplement form.

People with very dark skin are more vulnerable to vitamin D deficiency, as are those who live in countries with less sunlight.

Vitamin D plays several important roles in the body, including:

  • Helping the body use calcium and phosphorus – the body can only absorb calcium in the presence of vitamin D
  • Maintaining bone health and strength
  • Minimising risk of fractures and osteoporosis
  • Supporting muscle function
  • Supporting the activity of brain cells
  • Maintaining cardiovascular health
  • Reducing inflammation
  • Helping control infections
  • Reducing cancer cell growth

Low levels of vitamin D are more common in women than in men.

How Does Vitamin D Help Prevent Cancer?

Scientific research has demonstrated that people in sunnier parts of the world have lower rates of some cancers and that fewer cancer sufferers in these areas die from their disease.

They have also observed that:

  • There is likely a protective relationship between vitamin D levels in the blood and reduced risks of colon, breast, prostate, and ovarian cancers.
  • Vitamin D may certainly help prevent colorectal (bowel) cancer. Higher levels of Vitamin D in the blood seem to be associated with a lower chance of developing and dying from bowel cancer.
  • For women who have low levels of vitamin D, taking vitamin D tablets may help reduce their likelihood of developing the disease. It does not, however, demonstrably prevent breast cancer overall, although women who had normal, healthy vitamin D levels were significantly less likely to be diagnosed with breast cancer.
  • Women with breast cancer and low vitamin D were more likely to experience a recurrence of their disease and higher mortality rates.

How to Get Enough Vitamin D

Most people get adequate vitamin D with just 10 minutes of sun exposure on the skin per day during spring and summer. In winter, it may be more difficult. More than around 10 minutes of sun exposure is not going to increase your vitamin D levels, as the body can only generate so much at a time.

Taking care of your skin and being “sun-smart”, however, is particularly important in Australia, to prevent premature ageing and the risk of developing skin cancer. Melanoma rates in Australia are the highest in the world and this is among the most dangerous cancers affecting people as young as 20. This means that you may need to get enough vitamin D from other means.

Numerous foods contain vitamin D, including fatty fish, eggs, fortified milk products, soy products, fruit juices, and breakfast cereals.

Taking supplements including fish oil, cod liver oil, and vitamin D tablets may be beneficial.

Final Thoughts

It’s very important to understand that too much vitamin D can be as potentially harmful as too little. Too much vitamin D increases calcium levels in the blood and organs and this can increase the risk of calcification in the blood vessels, kidneys, heart, lungs, and pancreatic cancer. Excessive sun exposure does not influence vitamin D toxicity but does pose serious skin cancer and cosmetic risks.

It’s a good idea to have your GP check your vitamin D levels (with a simple blood test) before taking supplements and always take vitamin D supplements according to the dosage instructions on the label.