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.
Few women know that oral contraceptives lower the levels of such vital nutrients as Vitamin B2, B6 and B12, Vitamin C, folic acid, magnesium and Zinc. Mainstream hormone replacement (chiefly Premarin, but also Estratab and raloxifene) can also lead to deficiencies in Vitamin B6, magnesium and zinc.