Homocysteine
Homocysteine is produced in our own bodies. It can irritate blood vessels which may lead to blockages in the arteries.
The general recommendation for Folic Acid is to get about 400 mcgs. per day, mainly by eating fruits and vegetables.
So remember to eat your veggies! 
Hugs, Teri 
The following link offers some great info on this...
http://www.americanheart.org/presenter.jhtml?identifier=4677