I used to take big doses of vitamins like B and C, and still do E at times... Theres nothing wrong with them per se.. Its just that its more likely than not that artificial vitamins are incomplete sources(ie theres alot more higher numbered B vitamins than 12, but that seems to be the number everybody stops at)
Minerals might be a little different since theyre inorganic however I prefer taking them naturally when I can for the same reason that in nature they seem to have combinations that seem to assist in assimilation. I do take selenium.. Originally i took some liquid selenium I found at the vitamin shoppe.. then I didnt take any for a month or so.. then recently I bought some selenium from Walmart.. its source is from yeast and I seemed to have noticed a difference with that.. Either that or my body is just responding differently to me taking Iodine over the months??
to be honest I make homemade chocolate milk from raw milk, raw cacao, raw sugar, and blackstrap molasses.. it taste pretty good and its loaded with potassium and magnesium, etc etc...
I think if you find a food source you like that has the nutrients you need youll find that nature has already done the hard part of figuring out how much of each mineral & vitamin is in the food plus the proper ratio of each so that when you consume it your body will benefit much greater than if you went out and bought 25 different supplements and tried to figure it all out.