My naturopath but DH on Paternal Plus (Metagenics) and a Blackmores multi. The Paternal Plus is high in zinc, folic acid and selenium. I also have him on Vit C and magnesium.
The Naturopath recommended avoiding all caffeine for both partners, and limiting DH to three standard alcoholic drinks a week - apparently alcohol causes body to lose zinc and zinc makes the lovely sperm!
I hope that helps! Good luck!