People that feel their health getting worse might try to compensate with multivitamines? Also, the degenerate case of having a bad vitamine defficiency and als

People that feel their health getting worse might try to compensate with multivitamines? Also, the degenerate case of having a bad vitamine defficiency and also not taking vitamine pills might be too rare to show in the statistics. I mean about a third of the subjects take pills. How many does not take pills and would benefit greatly from it? Only those would move the needle.