Abstract
Background/Objectives: Erectile dysfunction (ED) is a common sexual disorder in men, frequently linked to endothelial dysfunction affecting penile vasculature. Accumulating evidence suggests that vitamin D (VD) status may influence endothelial function and, consequently, erectile function. VD deficiency has also been associated with cardiovascular risk factors, which are well-known contributors to ED. Methods: A systematic review following PRISMA guidelines was conducted, analyzing studies from PubMed and Cochrane databases published between 2010 and 2025. Randomized controlled trials, observational studies, and pilot clinical trials examining the relationship between VD levels and ED in the general male population were included. Results: Out of 1335 identified articles, 10 studies met inclusion criteria, encompassing over 13,000 men. Observational studies consistently showed that men with moderate-to-severe or arteriogenic ED had significantly lower serum VD levels and poorer erectile function scores compared to those with mild ED. VD deficiency was independently associated with higher ED prevalence, irrespective of lifestyle, cardiovascular risk, or sex hormone levels. Although several observational studies suggested a potential optimal vitamin D threshold, definitive recommendations cannot be established due to the heterogeneity of available evidence and conflicting findings from randomized controlled trials. The latter demonstrated inconsistent effects of vitamin D supplementation on erectile dysfunction outcomes, with the largest trial reporting no significant reduction in disease prevalence. These findings underscore the critical need for rigorously designed trials targeting populations with severe VD deficiency and arteriogenic ED. Conclusions: This systematic review highlights an association between vitamin D status and erectile dysfunction, particularly in men with moderate-to-severe or arteriogenic ED. However, most of the evidence is derived from low-certainty observational studies. While observational data suggest potential benefits of adequate VD levels for sexual health, well-designed randomized controlled trials are essential to delineate causal relationships and potential for therapeutic efficacy.