Am taking a Vitamin Supp. (in health food store) of Calcium Citrate 1000mg/Magnesium 400mg/Vit. D3 400 IU per?

If you take too many at one time your body will naturally excrete what it doesn't need (you'll pee it out), in turn, you're wasting vitamins. Take them throughout the day, that's your best bet. It's okay to take them with other supplements...I do it everyday.