A reappraisal of vitamin D effect on non-skeletal targets and mortality

There is an incessant debate in the current literature (with a parallel astonishing increasing number of papers) regard - ing possible beneficial health effect of adequate vitamin D status and vitamin D supplementation [ 1 ]. Indeed, in addition to its positive effects on skeletal [ 2 , 3 ] and mus - cle tissue [ 4 ], vitamin D has been claimed to be beneficial for patients with cardiovascular, malignant, autoimmune disease or infections, just to list a few of the at least 137 outcomes reported in the literature [ 5 ]. The interest in these extra-skeletal effects, also shared by the lay community, mainly stems from the observation that hypovitaminosis D can be easily estimated by blood testing and likewise eas - ily treated by supplementation [ 6 ]. Therefore, if an effect on non-skeletal tissues is demonstrated, it could represent a cost-effective public health measure to prevent or retard the progression of a number of diseases. Studies aimed at demonstrating the link between vitamin D and a specific target may be of different kinds (Table 1 )