The objective of this paper is to provide a current overview of the signifi
cance of zinc in human nutrition. To achieve this, the following issues are
addressed: (I) the biochemistry and biology of zinc in the context of thei
r relevance to zinc in human nutrition and to our understanding of the comp
lexity and practical importance of human zinc deficiency; (2) the history o
f our understanding of human zinc deficiency with an emphasis both on its b
revity and on notable recent progress; (3) the clinical spectrum of severe
zinc deficiency; (4) the lack of ideal biomarkers for milder zinc deficienc
y states, with the consequent dependence on randomized, placebo-controlled
intervention studies to ascertain their prevalence and clinical consequence
s, including growth delay, diarrhea, pneumonia, other infections, disturbed
neuropsychological performance and abnormalities of fetal development; (5)
the public health significance of human zinc deficiency in the developing
world; (6) reasons for concern and unanswered questions about zinc nutritur
e in the United States; (7) the need for better understanding of human zinc
metabolism and homeostasis (including its limitations) at a molecular, cel
lular, organ-system and whole body level and of factors that affect zinc bi
oavailability; and (8) potential strategies for the prevention and manageme
nt of human zinc deficiency, This review concludes with an emphasis on the
immediate need for expanded research in directions that have become increas
ingly well demarcated and impelling as a result of recent progress, which i
s summarized in this overview.