Results from a case-control study, published in a paper by Cattaruzza et al., showed a clear decrease in melanoma risk as vitamin D levels increased. The study included 137 cases of melanoma (blood samples collected at the time of diagnosis) and 99 healthy controls. Results were statistically significant and suggest that a majority of melanoma cases can be prevented with vitamin D levels of 30 ng/ml (75 nmol/L) or above.

The study concluded the following:

• The average vitamin D level of the melanoma patients was 10 ng/ml (25 nmol/L) lower than the average level of the healthy controls.
• A majority of the melanoma patients (66%) had vitamin D levels at or below 20 ng/ml (50 nmol/L) compared to just 15% of the healthy controls (as illustrated in the chart above).
• Participants with vitamin D levels at or above 30 ng/ml (75 nmol/L) had a 96% lower risk of melanoma compared to participants with levels at or below 20 ng/ml (50 nmol/L), adjusting for age, sex and BMI.