Vitamins & My Man.. Please Help!

My mans diet consist of a lot of meat, a lot of rice and probably 75% fast food. He isn’t overweight at all and if you saw him you’d actually probably think underweight but he’s tall so it evens out. My question is, do your boyfriends/partners take vitamins & do you guys think it’s beneficial for my bf to start since his diet isn’t the best ? Does his diet have a lot to do with sperm quality ?