Vitamin B-9 is best known as folic acid and it's a strange beast indeed. Paired with B-12, it increases the health of the heart and is important in the development of healthy red blood cells and the nervous system. It can be found in leafy vegetables, beans and asparagus.
While folic acid is generally associated with pregnancy in woman, that doesn't mean it's unnecessary for men. Studies have proven it contributes to and increased sperm count or spermatogenesis [source: Randerson]. But here's the major downside: B-9 supplementation may lead to an increased risk of prostate cancer, so it's best to take in folic acid through natural foods and not supplements [source: Boyles]. It's also good to be aware of your dosage and to not consistently overdo it.
And finally, in an age of multi-tasking, this next vitamin rises to the occasion.