Is cofactor for xanthine, sulfide,
and aldehyde oxidases.
D eficiency difficult to produce;
growth depression.
Not known.
Excessive exposure in parts o f the
Soviet Union associated with
goutlike syndrome.
Interacts with iron absorption;
may be a structural component
or cofactor o f a m etalloenzyme.
Depressed growth, hem atopoiesis,
and reproduction; disturbed
metabolism o f iron, copper,
and zinc; uitrastructural
changes in liver.
Not known.
Not known.
Selenium **
Is glutathione peroxidase cofactor;
in type 1 dciodinase; interacts
with heavy metals.
Depending on species, muscle
degeneration, pancreatic
Endemic cardiomyopathy
conditioned by selenium
D eficiencies and excesses known
in parts o f China; deficiency
due to total parenteral nutrition.
Involved in calcification and as
cross-linking agent contributing
to the architecture and resilience
o f connective tissue.
Growth depression; structural
abnormalities o f the skull and
long bones; decreased amounts
o f collagen and hexosam ine
in bone.
Not known.
Not known.
Perhaps involved in regulation
o f a phosphoryltransferase
Growth depression; impairment
o f reproduction and lipid
metabolism; none o f these are
reliably reproducible.
Not known.
Not known.
Is cofactor for enzym es
o f energy metabolism,
transcription, and translation.
Failure to eat; severe growth
depression; sexual immaturity;
skin lesions.
Growth depression; sexual
immaturity; skin lesions;
change of taste acuity;
decreased immunocompétence.
D eficiencies known in Iran and
Egypt; with total parenteral
nutrition; due to genetic disease,
traumatic stress.
‘Modified and reproduced, with permission, from W. Mertz: The essential trace elements,
S c i e n c e ,
213, 1332 (1981); and F, H. Nielsen: Ultratrace elements in nutrition.
A n n u . R e v . N u t r .
4,21 (1984).
f Bromine, cadmium, lead, and tin are not listed here because the evidence ft* their being essential is weak.
¥Probably essential, but farther studies are needed to establish this.
% is uncertain whether fluorine should 1» considered an essential element or a pharmacological agent. A fluoride concentration in drinking water of 0.9-1.0 mg/L is prophylactic for dental caries: consumption of
water with fluoride concentration greater than 1.5 mg/L, during the years of tooth development, produces mottling.
"Discussed in Chapter 30.
'iron and iodine are not true “trace" elements because of their relatively high daily requirements and their high concentrations in the body.
“Discussed in Chapter 29.
“ Interactions with vitamin E may also be important.
fu n ction s for arsenic, boron, fluorine, lithium, nickel, silicon, and vanadium are still partially or completely hypothetical. They are based on the symptoms of the deficiency diseases produced.
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