@browncoat - The ability to lose vitamins and minerals or other nutrients is actually one of the main factors in a recommended daily intake for most things.
B vitamins, and vitamin C, for example, are not stored in the tissues like iron and are lost every time a person sweats or urinates, so you have to replenish them daily. Incidentally, because they are water soluble they often get boiled out of vegetables and poured down the sink as well.
So people are relatively safe having mega doses of vitamin C, because the body just processes and flushes anything it doesn't use. I don't think that huge amounts of vitamin C are necessarily better for you than a balanced amount, but they won't do the harm that overdosing on other kinds of vitamins or minerals will. Which is why you have to be careful when taking vitamins to check what is actually contained in the supplement. Often there will be more than one thing in there and one might be safer than the other to take in bigger quantities.