SACN published an extensive review of the evidence on vitamin D, the most prescribed dietary supplement, in July 2016.9

New research since then may add to the SACN guidance. The 2018 Toronto study into VMS and cardiovascular outcomes above concluded that €sufficient studies on vitamin D exist to be confident that there is no all-cause mortality effect.€4

An international Mendelian randomisation study (taking into account known gene effects in observational studies) looked at whether circulating 25-hydroxyvitamin D (25(OH)D) levels in the body are causally associated with the risk of cancer. They assessed over 70,000 patient records covering seven cancer types (prostate, breast, lung, colorectal, ovarian, pancreatic and neuroblastoma).10

The researchers said there was €little evidence for a linear causal association between circulating vitamin D concentration and risk of various types of cancer.€ However, €the existence of causal clinically relevant effects of low magnitude cannot be ruled out.

€Our results, in combination with previous literature, provide evidence that population-wide screening for vitamin D deficiency and subsequent widespread vitamin D supplementation should not currently be recommended as a strategy for primary cancer prevention.€