Association between folic acid, homocysteine, vitamin B12 and erectile dysfunction-A cross-sectional study.

To evaluate the relationship between serum levels of folic acid (FA), homocysteine (HCY), vitamin B12 (B12) and erectile dysfunction (ED) and to explore their internal relationships. The study included 134 ED patients and 50 healthy controls. ED was assessed using IIEF-5 scores. ED group had lower median FA (6.08 versus 10.21; p < .001) and B12 (256.0 versus 337.5; p < .001) levels, and higher median HCY (11.4 versus 7.95; p < .001) levels, and these differences seemed to be more pronounced in the younger participants (age < 35 yr). FA decreased with the severity of ED (7.52 versus 6.15 versus 5.49 versus 3.97; p < .001), while HCY increased (10.35 versus 11.8 versus 12.9 versus 15; p < .001). Smoking and shift work were associated with lower FA levels. Multivariate analysis showed that serum FA and HCY revealed significant relation with ED. ROC analysis showed that FA ≤ 8.84 and HCY ≥ 10.35 were the best cut-off values for ED diagnosis. Both FA (r = -0.703, p < .001) and B12 (r = -0.576, p < .001) were negatively correlated with HCY. In conclusion, low FA levels and high HCY levels might be independent risk factors for ED. Low serum FA and B12 levels might co-cause high HCY levels and lead to ED.