You're speaking from personal experience? Did you conduct trials on yourself? Were you really able to discern a difference in your state of health while taking one brand of MV, as opposed to another? What parameters were you measuring and recording, on a daily basis?
Regards,
Years ago, I noticed that cheap multivitamins consistently resulted in me getting a cold. It happened several times in a row and put me off taking vitamins for some years. I later learned of the anti-vitamin effect with cheap multivitamins.