The impact of zinc and folic acid supplementation on sperm DNA methylation: results from the folic acid and zinc supplementation randomized clinical trial (FAZST)

Objective: To determine if 6-month folic acid (5 mg) and zinc (30 mg) supplementation impacts sperm DNA methylation patterns. Design: A multicenter, double-blind, block randomized, placebo-controlled trial titled “The Folic Acid and Zinc Supplementation Trial (FAZST).” Setting: Infertility care centers. Patient(s): Male partners (18 years and older) from heterosexual couples (female partners aged 18–45 years) seeking fertility treatment were recruited. Intervention(s): Men were randomized 1:1 to receive folic acid (5 mg) and elemental zinc (30 mg) (n = 713) or a matching placebo (n = 757) daily for 6 months. Main Outcome Measure(s): Sperm DNA methylation was analyzed using the EPIC methylation array (Illumina) at 6 months. Differential sperm DNA methylation was assessed at multiple levels (regional, single cytosine phosphate guanine, etc.). We additionally assessed the impact of supplementation on epigenetic age. Result(s): No significant differences were identified between the treatment and placebo groups although some trends appeared to be present. To determine if these trends were noteworthy, we implemented various permutations and found that the patterns we identified were no more than would be expected by random chance. Conclusion(s): The data presented here strongly suggest that this supplementation regimen is not effective at altering sperm DNA methylation. These data comport well with previous findings from the FAZST study that found no impact of supplementation on basic semen analysis parameters or live birth. Clinical Trial Registration Number: ClinicalTrials.gov Identifier: NCT01857310.