 Molybdenum (Mo) is an essential nutrient for animals
and humans. Tissue content of molybdenum is low, with the highest
concentrations in the liver, kidney, adrenal gland and bone. It is a
component of a number of enzymes, including sulfite oxidase (involved in
the metabolism of sulfur amino acids), xanthine oxidase (involved in the
oxidation of purines and pyrimidines and the production of uric acid),
and aldehyde oxidase (involved in the oxidation of aldehydes). These
enzymes share a common "molybdenum cofactor."
Deficiencies: Molybdenum deficiency is extremely
rare and has only been identified in the presence of other serious
disorders. Metabolic defects in the molybdenum cofactor are
characterized by the absence of the three molybdoenzymes. Both the
deficiency and the metabolic disorders are accompanied by abnormal
excretion of sulfur metabolites, low uric acid concentrations, and
elevated hypoxanthine and xanthine excretion. The absence of sulfite
oxidase in the metabolic disorder leads to death at an early age. Without
sufficient amounts of Molybdenum to metabolize them, some of these
substances may build up to toxic levels and cause auto-immune disorders.
Diet recommendations: The Estimated Safe and
Adequate Dietary Intakes of molybdenum (µg/day) are: 15-30 at age 0-6
months, 20-40 for 6-12 months, 25-50 for 1-3 years, 30-75 for 4-6 years,
50-150 for 7-10 years, and 75-250 for adolescents and adults. This range
is based on the usual dietary intake, about 75 to 240 µg/day by adults.
The range was extrapolated for other age groups on the basis of body
weight.
Food sources: Rich sources of molybdenum include
legumes, cereal products, and leafy vegetables. The amount in foods
depends on the soil molybdenum content. Molybdenum is very well
absorbed, but its bioavailability may be affected by some food
components.
Toxicity: Molybdenum toxicity is much more likely
than deficiency. Toxicity is common in cattle grazing in pastures with
high molybdenum soil. A high incidence of gout has been reported in
humans with intakes of 10-15 mg/day.
Recent research: Controlled studies in humans
suggest that the molybdenum requirement is well below the usual dietary
intake, which is consistent with lack of molybdenum deficiency in the US
population. Bioavailability studies suggest that molybdenum is less well
absorbed from soy products than from leafy vegetables.
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