This is a great post! As in my previous survival posts, I have noted that multi vites are worth their weight in gold, because NO ONE can effectively fight or have a decent chance of survival if they are sick.
Obviously, if TSHTF, the first few months may be allright, but longer than that, a SUPPLEMENT(which is how multi vites are intended to be used) may be required.
A good diet, and healthy eating means that MOST wont ever need to take a MV, but I cant hurt.
I also use Zinc when I feel ill(boosts immune system response) as well as folic acid(VIT C).
I keep flintstones around for my kids as well.
Since taking multi vites, eating healthier, excercising and washing my hands several times daily(sound silly but it works), I have noticed that I may catch a cold once a year.
For proper nutrition during survivial situations, I reccomend purchasing an outdoor survival book that outlines edible vegetation and proper animal preparation and storage.
Keeping seeds around(dried) and a compost heap in the yard ALSO means that you can create an INDOOR or OUTDOOR garden.