In the normal state, blood has no business anywhere except in the confines of the heart and blood vessels and in the sinusoids of the marrow, liver, and spleen. Of the average 5 L of blood, only 2.25 L, or 45%, consists of cells.
Take-away: Calcium and magnesium may best be taken in the evening with food or before nighttime sleep. Since zinc should not be taken with calcium and apart from iron, it is most useful if taken earlier in the day either slightly before/after food. Iron should ideally be taken on an empty stomach and separately from other multivitamin/multimineral combinations.
While you need to get some zinc every day, too much zinc -- from over-consuming vitamin supplements or using zinc nasal sprays -- threatens your health. If you overdose on zinc, you might notice a number of symptoms caused by the toxic effects of the mineral.