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.
This means that, for an adult, taking more than 40 milligrams of zinc daily is too much. For children between 9 and 13 years of age, more than 23 milligrams of zinc is too much. Adolescents between 14 and 18 years should not consume more than 34 milligrams daily. Consuming more than the UL of zinc may cause abdominal cramping, vomiting, diarrhea, severe headaches, nausea and a decreased appetite.