I'm a 53 year old male who, at the recommendation of my doctor, began taking folic acid with vitamin D for heart health. While I'm not sure of the heart health end of it, I am sure of the libido and sperm production and hair growth. I don't claim to know all the chemical and physiological makeup of my body, but I do know that my libido has increased significantly.
As for hair growth, I was developing a "thin spot" on top, but this spot seems to be thicker and less noticeable now. Upon researching these "new found benefits," I have read where folic acid and vitamin D increase the chance of developing prostate cancer. Go figure!