Is vitamin B12 a tonic?
D002986:Clinical Trials as Topic; D005221:Fatigue / Q000188:drug therapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D010919:Placebos; D014805:Vitamin B 12 / Q000627:therapeutic use*
D010919:Placebos; D014805:Vitamin B 12