Vanadium is an essential mineral in mammals, and both tetravalent and pentavalent vanadium compounds are important biologically. Vanadyl salts such as vanadyl sulphate are available commercially in supplement form. Vanadium has been observed to have an insulin mimetic effect, with oral administration of vanadium compounds appearing to stimulate hexose transport, lower blood glucose levels, inhibit lipolysis, stimulates glucose oxidation and stimulate glycogen synthesis. As with insulin, vanadium compounds appear to stimulate potassium uptake to cardiac muscle and stimulate DNA synthesis. The insulin mimetic effects of vanadium in animals have lead to speculation that the compound is required for normal function of the insulin system. However, the pharmacological effects of vanadium may be different from a more subtle nutritional role in the function of the insulin system of mammals. Vanadium is considered essential in many mammals, and low intakes cause dysfunction in blood sugar regulation.
Pharmacologically, vanadyl sulphate has been shown to be a useful blood sugar regulating agent. Because of these effects, the efficacy of vanadyl sulphate has been investigated on diabetic human subjects. For example, in one study1 researchers administered 75, 150 or 300 mg of vanadyl sulphate to diabetic subjects for 6 weeks and then performed a euglycaemic clamp test to determine the blood sugar control in the subjects. While none of the subjects receiving the lower dose showed improvement, the 150 and 300 mg doses were effective at improving glucose metabolism in a number of subjects. Fasting blood glucose and the amount of glycated haemoglobin (haemoglobin A1C, a marker for high blood glucose levels) was significantly lowered by the 150 and 300 mg doses of vanadyl sulphate. At the highest doses of vanadyl sulphate the total cholesterol was also significantly reduced, but this was accompanied by a reduction in high density lipoprotein (HDL) cholesterol also.
Therefore vanadyl sulphate may be a useful blood glucose modulating agent in diabetic subjects. The authors reported no correlation between the blood levels of vanadium and the clinical effects. This study is typical of most involving vanadium, in that there are positive results for certain subjects, but not others, and that the benefits to vanadyl sulphate are small. However, most studies involving vanadium salts concentrate on short term pharmacological effects of high doses of vanadium salts such as vanadyl sulphate. Longer term studies assessing the nutritional role of vanadium and its possible essential role are lacking. Foods tend to contain very little vanadium, but only very small intakes may be required. Shellfish, green leafy vegetables and whole grains may be the best sources of vanadium, but some multivitamin and multimineral formulas contain vanadium salts. In animals, vanadium deficiency induces growth retardation, blood sugar irregularities and bone deformation, but human requirements are not understood.
RdB
