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VOL. 70 (4), 961-999, 2004 VANADIUM - AN ELEMENT BOTH ESSENTIAL AND TOXIC

Vanadium-deficient nanny-goats had only 50% the life-span of
control goats. The normative requirement of vanadium for animals
is very small, amounting to < 10 µg/kg dry feed matter (12, 6, 7, 14,
2, 9, 10).

Essentiality to Humans

The same is true for the normative vanadium requirement of
man. A daily dietary intake of 10 µg or less probably would meet any
postulated normative requirement (7, 3, 92, 93). The individual daily
intake of vanadium in Germany and Mexico in every case reached
> 8 µg/day on a week’s average. World-wide, typical diets generally
supply 15 to 30 µg V/day (85, 30, 29, 44, 98).

Pharmacological Effects

To disentangle pharmacological from nutritional observations it
is necessary to identify the essential biochemical function of vana-
dium in higher animals. Both effects demand quite different amounts
of vanadium (µg or mg/kg food). On the other hand it is difficult to
distinguish pharmacological from toxic doses of vanadium. The dif-
ferences are species-specific and dependent on time, mode of admi-
nistration, and the chemical form of vanadium. In the past, the
amounts of vanadium used in in vitro and in vivo experiments were
mostly pharmacological or toxic doses, and much higher (thousand-
fold) in comparison to the nutritional intake of animals and man.

Vanadium and its compounds mimics the actions of insulin in
isolated cell systems, and these compounds produce dramatic de-
creases in blood glucose levels in animal models of both types of
diabetes mellitus (50, 108, 119). In vitro and in vivo studies with
animals indicated that vanadium increases the glucose transport ac-
tivity and improves glucose metabolism (24). The action of vana-
dium is related to the translocation of glucose through the plasma
membrane. Inhibition of phosphotyrosine, phosphatase and protein
tyrosine kinase activation is probably involved in the action of vana-
dium on glucose homeostasis (111). The enhancement of glucose
uptake, glucolysis and glycogen synthesis by vanadate is less than by

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