Table 1.

Zinc deficiency contributing to anemia.

1.  In clinical investigation	References
(1) In most cases, zinc deficiency coexists with iron-deficiency anemia
a.Mostly in women of reproductive age (because they lose blood during menstruation)	[33,34,35,36,37,38,39,40]
b.Mostly in preschool children (because infants need increasing iron and zinc)	[26,41,42]
c.In adults (relatively rare)	[43,44]
d.The reason for the coexistence of zinc deficiency with iron deficiency (The major reason is zinc and iron coexist in food and have same inhibitor, phytate)	[10,45,46]
(2). To a lesser extent, zinc deficiency may cooperate with other factors to lead to anemia	[31,45,51,52]
(3). No reports in humans recognize zinc as a primary factor	[31,45,51]
2.  In animal model studies
(1). Zinc is essential for erythropoiesis	[57,58,59,60,61,62,63,64]
(2). In rats, iron deficiency or iron+zinc deficiency results in anemia, but not zinc deficiency alone	[61,65,66]
3.  A hypothesis is presented: zinc deficiency might need to cooperate with other factor(s) to lead to anemia. In humans the main cooperate factor might be iron deficiency, the minor cooperate factor(s) might be other nutritional deficiency or disease