From the publication:

In this systematic review and meta‐analysis of RCTs, vitamin D supplementation had no significant effect on TT [total testosterone] and SHBG in men. In term of intervention, treatment duration (<16 or ≥16 weeks), type of prescription (weekly or daily), daily doses of vitamin D supplementation (<3,000 IU/day or ≥ 3,000 IU/day) and baseline 25(OH)D [40 nmol/L or lower or higher than 40 nmol/L] and TT [total testosterone] levels confirmed the null finding in total analysis. Our results are consistent with the current systematic review (Trummeret al., 2018), which found conflicting results about the effect of vitamin D supplementation on TT in men in RCTs and observa‐tional studies.

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The main outcome of this study reaffirmed the null effect of vitamin D supplementation on TT and SHBG in men. To solve this problem in the future, we recommend further studies that consider the effect of vitamin D over a longer period in men with hypogonadism and severe vitamin D deficiency.