Daily intake of vitamin D could help reduce cancer mortality

According to a comprehensive evaluation conducted at the German Cancer Research Centre, the intake of vitamin D on a daily basis has the potential to reduce cancer mortality in the population by twelve percent. This conclusion is based on an analysis of 14 meticulously conducted studies, encompassing a substantial participant pool of nearly 105,000 individuals.

Vitamin D deficiency is a global issue affecting a significant portion of the population, and it is particularly prevalent among individuals diagnosed with cancer. On average throughout the year, approximately 15 percent of German adults have vitamin D blood levels below the threshold for a significant deficiency. In a specific study focusing on colorectal cancer patients, researchers found that 59 percent of the participants had a deficiency of vitamin D3, which was also linked to an unfavorable prognosis.

Possible effects of vitamin D supplementation and the development or prognosis of cancer have already been investigated in numerous studies. "According to current studies, vitamin D3 intake probably does not protect against cancer, but it could reduce the probability of dying from cancer. However, the previous studies on cancer mortality have given very different results and we were interested in the reasons for this," says Ben Schöttker, epidemiologist at the German Cancer Research Center.

In order to examine the impact of vitamin D3 on cancer mortality rates in the general population and the survival outcomes of cancer patients, Ben Schöttker and his colleagues conducted a systematic review of the existing literature. Through this process, they identified 14 studies involving a significant total of nearly 105,000 participants. It is worth noting that the researchers specifically focused on studies of the highest quality, where participants were randomly assigned to either the vitamin D3 group or the placebo group. This rigorous approach ensured that only the most reliable and credible studies were considered for their analysis.

Age and Timing of Intake Influence Efficacy

Upon summarizing the results of all 14 trials, no statistically significant findings were observed. However, when the trials were segregated based on the frequency and dosage of vitamin D3 administration, notable differences emerged. In the four studies involving high single doses, there was no discernible effect on cancer mortality. Conversely, in the analysis of the ten studies involving daily dosing, the researchers identified a statistically significant 12 percent reduction in cancer mortality.

"We observed this 12 percent reduction in cancer mortality following the administration of untargeted vitamin D3 to individuals, regardless of their vitamin D status. It is reasonable to assume that the effect is even greater for those individuals who actually have a vitamin D deficiency," explains Ben Schöttker. He further elaborates that the enhanced efficacy of daily vitamin D3 doses could be attributed to the more consistent bioavailability of the active hormone 1,25-dihydroxyvitamin D, which is generated through vitamin D reactions within the body and is believed to inhibit tumor growth.

A more detailed analysis of the studies with daily intake revealed that individuals aged 70 and above derived the greatest benefit from vitamin D3 therapy. Furthermore, the effect was most pronounced when vitamin D supplementation was initiated prior to the diagnosis of cancer.