That means it is the form the human body can actually use in circulation.
It goes by several other common names including:
Methylfolate
L-5-Methylfolate calcium (refers to the calcium salt molecule it is attached to)
5-MTHF and L-5-MTHF
Levomefolic acid
5-methyltetrahydrofolate
(6S)-5-methyltetrahydrofolate and Magnafolate.
The letters or numbers before the name refers to the 3D chemical structure of that compound.
Some products may only list Methylfolate or 5-MTHF, without specifying if which form it contains.
If the label does not state L-5-Methylfolate, Magnafolate or Metafolin then it may not be the biologically active form.
Magnafolate® ,the Manufacturers & Supplier of L-5-Methylfolate.