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.
However, just taking Zinc alone can cause serious side effects as Zinc will cause a Copper detox as the body dumps this excess copper and Mercury and other heavy metals from the tissues. This can cause rashes and flu-like symptoms.