have no risk of inducing adverse effects for the general population. Due to lack of data indicating adverse effects of silicon, it is not possible to establish a UL.
The physiological role of silicon and how this role relates to human health.
The possible role of silicon in atherosclerosis and hypertension, several bone disorders, Alzheimer’s disease, and other conditions common to the elderly because of the prevalence and cost of these disorders.
The determination of a reliable indicator of silicon status.
A functional role for vanadium in higher animals and humans has not yet been identified. Vanadium mimics insulin and stimulates cell proliferation and differentiation (Heyliger et al., 1985; Nielsen and Uthus, 1990). Vanadium inhibits various ATPases, phosphatases, and phosphoryl-transfer enzymes (Nielsen, 1985). The response of thyroid peroxidase to changing dietary iodine concentrations has been shown to be altered in vanadium-deprived rats (Uthus and Nielsen, 1990). Vanadium-deprived goats show elevated abortion rates and decreased milk production (Anke et al., 1989). In vitro, vanadium in the form of vanadate regulates hormone, glucose, and lipid metabolism; however, vanadium most probably exists in the vanadyl form in vivo (Rehder, 1991).
Vanadium in the forms of vanadyl sulfate (100 mg/day) and sodium metavanadate (125 mg/day) has been used as a supplement for diabetic patients (Boden et al., 1996; Cohen et al., 1995; Goldfine et al., 1995). Although insulin requirements were decreased in patients with Type I diabetes, the doses of vanadium used in the supplements were about 100 times the usual intakes (Pennington and Jones, 1987), and they greatly exceed the Tolerable Upper Intake Level (UL) for vanadium.