There are pros and cons to vitamin/mineral supplements in the first place. 60 Minutes had a segment on aging where a study followed 14,000 people from age 52 into their 90s (those who lived on) and NONE took supplements and NONE were vegetarians. That said I still believe in supplements.
In the 80s when gear was legal the sports med Docs injected your Test/Decca with bright pink B-12. My Doc also did a liver/mixed Bs cocktail. I felt the boost.
I had a friend dying of liver cancer from being exposed to Agent Orange in Viet Nam. His chemo would zap all his energy so I gave him a liver/mixed Bs shot several times a week. His quality of life was so much better until the inevitable end.
Sub lingual B-12 and B-12/folic acid tablets work and are absorbed. Unlike orally.