Higher Vitamin D Levels and Lower Cancer Risk

Higher levels of vitamin D are associated with a substantial reduction in the risk (more than 65%) of all invasive cancers combined, according to a new study published in April. This throws more weight behind ensuring that we all get sufficient vitamin D, either through sun exposure, diet or vitamin D supplements.

I have written recently in a previous newsletter about the importance of vitamin D in skin cancer. A previous study showed that women randomly assigned about 1000 IU of vitamin D per day had a 77% reduction in their incidence of all cancers.

This study was published online on April 6 in PLOS ONE and involved 2304 women, with an average age of 64 years (range, 60 to 69 years) with vitamin D levels between 75 nmol/L and 120 nmol/L. The women were randomised into three groups:

  • calcium (either 1400 mg/day of calcium citrate or 1500 mg/day of calcium carbonate) plus vitamin D placebo
  • calcium plus 1000 IU/day of vitamin D₃
  • calcium placebo plus vitamin D placebo (control group)

The researchers then noted the incidence of invasive cancer, with the exception of skin cancer, over a median of 3.9 years. During the observation period, 58 women were diagnosed with cancer. The most common cancer diagnosed during the study was breast cancer, which accounted for 43% of all cancers.

Cancer incidence declined with increasing vitamin D levels. Women with vitamin D of at least 100 nmol/L had a 67% lower risk for cancer than women with levels of 50 nmol/L or less.

We have come out of summer after a scare campaign of “Slip, Slop, Slap” from the Anti-Cancer Council Australia. Vitamin D levels are no longer covered by the Medicare rebate, and doctors are still giving advice that vitamin D supplements are unnecessary and a waste of money.

But wait there is more!

In yet another recent study:

Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort.

In this study non-smokers who stayed out of the sun had a life expectancy similar to smokers who soaked up the most rays, according to researchers who studied nearly 30,000 Swedish women over 20 years.

Really!

This indicates that avoiding the sun “is a risk factor for death of a similar magnitude as smoking,” compared with those with the highest sun exposure, write the authors of the article. In this study women who had more sun exposure, were generally at lower risk for cardiovascular disease (CVD) and non-cancer/ non-CVD diseases such as diabetes, multiple sclerosis, and pulmonary diseases, than those who avoided sun exposure.

The researchers acknowledge that longer life expectancy for sunbathers seems paradoxical to the common thinking that sun exposure increases risk for skin cancer.

“We did find an increased risk of…skin cancer. However, the skin cancers that occurred in those exposing themselves to the sun had better prognosis,” said one of the study authors. Sweden’s restrictive guidance against sun exposure over the past 4 decades may be particularly ill-advised, the study finds, in a country where the maximum UV index is low (< 3) for up to 9 months out of the year.

One of the strengths of the study was that results were dose-specific – sunshine benefits went up with amount of exposure. When smoking was factored in, even smokers at approximately 60 years of age with the most active sun-exposure habits had a 2-year longer life expectancy during the study period compared with smokers who avoided sun exposure.

So girls (and guys), have your vitamin D levels checked – even if you have to pay for it! Make sure your vitamin D levels are at least 100 nmol/L or more. A small price to pay to ensure you have an optimal health outcome.