Folic acid ( also known as vitamin B9 , vitamin Bc or folacin ) and folate , as well as pteroyl-L-glutamic acid , pteroyl-L-glutamate , and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9 . Folic acid ( also known as vitamin B9 , vitamin Bc or folacin ) and folate ( the naturally occurring form ) , as well as pteroyl-L-glutamic acid , pteroyl-L-glutamate , and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9 .