The proposal was also made that the term 'folic acid' be changed to folate.
The positive list forms part of the 2002 Food Supplements Directive. The additions are proposed to reflect substances that have been evaluated by EFSA and received a positive opinion.
The consultation on the additions launched this week applies only to Wales, but the FSA has said that parallel implementing legislation will be made In England, Scotland and Northern Ireland.
Member states have until April 30 to make changes to their legislation to allow the approved substances. The FSA is also seeking opinions on how the additions may reflect the existing market.
Merck Eprova's calcium-L-methylfolate, better known as Metafolin, is a patented form of folate with superior bioavailability to synthetic folic acid.