According to a new review published in JAMA (The Journal of the American Medical Association), higher intakes of vitamin D may be linked to lower incidences of advanced cancer, based on epidemiologic and clinical trial data sourced from VITAL, a double-blind, placebo-controlled clinical trial which evaluated the outcomes of men over the age of 50 and women over the age of 55 who supplemented daily with vitamin D3 and omega-3 fatty acids.
 
The primary endpoints of the trial were set to evaluate cardiovascular outcomes over a period beginning anywhere from November 2011 to March 2014, ending in December of 2017. 25,871 participants in total participated in the study, all of whom were free of cardiovascular disease and cancer at baseline, and among these participants, 1,617 were diagnosed with invasive cancer over a media intervention period of 5.3 years. Across both the placebo group and the supplementation group, none of the participants were deficient in vitamin D, the researchers wrote.
 
In the review of VITAL, the primary outcome researchers investigated a composite incidence of metastatic and fatal cancers, which were considered advanced by the researchers. The results of the trial were modified for certain factors, such as overweight or obesity, and it was found that among those who had incidences of metastatic or fatal cancer, there was a significant reduction in vitamin D concentrations, compared to participants who did not have any advanced cancer incidences.
 
The protective effect of vitamin D against cancer risk was observed much more strongly in participants who had a healthy BMI, the researchers wrote. Additionally, the risk reduction was independent of the type of cancers which the participants were diagnosed with, meaning that the preventative effect did not apply to prostate cancer alone.
 
“Although these findings could be due to chance, obesity is known to affect the vitamin D axis,” the authors wrote. “The larger storage capacity for vitamin D in individuals with obesity by fat sequestration or volumetric dilution may result in lower plasma vitamin D. Yet in the overall VITAL cohort, neither individuals with or without obesity were deficient in vitamin D following supplementation. Parathyroid hormone level, a marker of vitamin D efficacy, is higher in individuals with obesity compared ot lean individuals at a given 25(OH)D level, which would be consistent with obesity-related hormonal dysregulation and less supplementation benefit.”