couple things I've learned/been told about vitamins:
> Your body can only handle so much of any vitamin at a time - so if you take 2 or more, try to space them out. Also, some vitamins/minerals absorption rates lower when taken in conjunction with certain types of foods.
> The gnc person told me that you can do this test with your multi- stick it in a cup of vinager. If it dissolves, it is a good one - your stomach will be able to break it down and absorb it. If not.... my dh's gnc multi did dissolve, as did my Sun Harvest (grocery brand) pre-natals and HEB (grocery brand) multi's.
> Calcium - I've read your body loses the most calcium at night because normally, you are not getting any calcium sources while your sleeping (unless you get up in the middle of the night to snack!!) I take my multi at night, sometimes additional calcium for this reason.
happy shopping!