Despite notable recent advances in our appreciation of the role of trace elements
in human nutrition and disease, clinical detection of trace-element-deficiency states
usually remains extraordinarily difficult.
Although several trace elements, such as iron, copper, zinc, chromium, selenium,
manganese, cobalt, iodine, and fluorine, are considered to be essential for human
health, only a few have clinical relevance.
With the advent of present-day tools and techniques of analysis, it is possible
and practical to measure accurately the essential trace element content of human
Of the 90 naturally occurring chemical elements, 26 have been suggested as
essential for animal life (1). In addition to these, a number are of toxicological
importance (e.g., Pb), and some others are of interest because of their special
properties (e.g., as components of therapeutic agents).
Nutritional regulation of host resistance and susceptibility to infection has been
suspected by generations of clinicians and investigators. It is only recently, however,
that the critical evidence supporting the role of dietary factors in various aspects
of immune responses has been collected and analyzed (1,2).
Modern trace element research is concerned at present with 17 elements, the
essentiality of which has either been established or is suspected. Even when we
concentrate on the seven or eight elements for which problems of deficiency or
excessive exposure are known to occur in man, the multitude of their individual
metabolic pathways, requirements, and interactions with the environment represents
a very large compilation of data that is essential for understanding the nutritional
situation but extremely difficult to comprehend.
A comprehensive review of the role of all trace elements in fetal and neonatal
development here is possible at only the most superficial level. Therefore two trace
elements, zinc and manganese, are used to exemplify the concepts involved.
This chapter considers the trace elements which have been studied most extensively
in pregnancy and lactation (i.e., zinc, copper, selenium, and chromium) but
Infancy is a stage in the life cycle characterized by several unique features. With
the possible exception of the rate in utero, growth during infancy far exceeds that
experienced throughout life.
Four groups of infants and children have been identified as being at risk of
developing acute trace metal deficiency: (a) children with chronic diarrhea (1); (b)
children and infants on total parenteral nutrition (2); (c) infants with inborn errors
of metabolism; and (d) premature infants (3).
Perusal of most medical textbooks shows that childhood malnutrition in the
tropics has been consistently ascribed to feeding a diet deficient in either protein
or energy, or some combination of the two. Kwashiorkor is said to result from
"pure" protein deficiency, whereas marasmus arises from protein and energy deficiency.,
Anthropologists believe that the aboriginal people migrated to Australia some
40,000 to 50,000 years ago. It is not known from whence they came, but they do
have variant forms of the enzyme carbonic anhydrase in their red blood cells (1) a
finding discovered only in certain areas of northwest India.
Lead, arsenic, cadmium, and methyl mercury are nonessential and potentially
highly toxic metals. They may be found in minute and variable but measurable
amounts in food, drinking water, and/or ambient air.
During the past decade there has been a large upsurge in interest in nutritionally
essential trace elements. In the clinical field the recognition that deficiency can
occur in human subjects in many practical dietary situations has been of crucial
importance from the public health viewpoint worldwide.
Keshan disease is an endemic cardiomyopathy which was first observed in Keshan
County, Heilonjiang Province, Northeast China. It has a very high case-fatality
rate, more than 80% in the past and around 30% at present. The disease may be
acute, subacute, chronic, or insidious.
Iodine is an essential trace element whose only confirmed function concerns the
formation of thyroid hormones. Our knowledge of the disorders caused by deficiencies
in the dietary supply of many trace elements has markedly increased only
during the last decade. Iodine is one exception to this rule.
Aboriginal boys, 209-227
genetic differences, 226
measurement techniques, 42-45,75-85
and trace element metabolism, 107-110
Acquired zinc deficiency,