The U.S. Food and Drug Administration does not approve dietary supplements, but it holds veto power over their introduction into interstate commerce. 
Dr. Aardsma filed a New Dietary Ingredient Notification for vitamin MePA with FDA, as required by law, July 7, 2017.
FDA has seemed uncertain what to do with vitamin MePA, perhaps because it is the first new vitamin to be discovered since the late 1940s.
Dr. Aardsma’s correspondence with the FDA is available here.