My personal conclusion from own research (I mean googling, discussions, own experiences etc. not a strictly scientific approach :-) is that
- it is preferable to take vitamins, minerals etc. from normal food, as part of a balanced diet
- needs and availability are different in winter than in summer, so it may make sense to use some supplements during wintertime, however we don't use supplements during the summer
- most critical may be vitamin D and Omega 3, this is what we give to our children during winter, when low exposure to sunlight means the body has less chance of producing the necessary amount of vitamin D. Also, in our country very little fish is eaten on average, so we feel it makes sense to supplement Omega acids.
Vitamins from artifical supplements probably aren't digested by our body nearly as well as in their natural environment, so even if I take 500mg of vitamin C in a pill, it may be that less of it is actually used by my body than of the 50mg I get from fruits and vegetables. Moreover, the latter also contain hundreds of other, as yet unknown or un-examined compounds, which may have a positive health effect on their own, but what may be even more important is their synergistic effect. Food science only focuses on singular compounds, isolated from the whole, one at a time, and has much less knowledge about how they actually work together in their natural environment. Not to mention it is much less exciting - and even less profitable - to advertise raw carrotsbroccoli or apples rather than "our super immune boosting mega vitamin supplement"Super Immune Boosting Mega Vitamin Supplement" including lots of fancy and deeply scientific(ally sounding) names such as Flavonoids, Carotenoids, Antioxidants etc. ;-)