The absorption of ingested vanadium is less than 5 percent, and therefore most ingested vanadium is found in the feces. Absorbed vanadate is converted to the vanadyl cation, which can complex with ferritin and transferrin in plasma and body fluids (Harris et al., 1984; Sabbioni et al., 1978). Highest concentrations of vanadium are found in the liver, kidney, and bone. However, very little of the absorbed vanadium is retained in the body. Patterson and coworkers (1986) investigated vanadium metabolism in sheep and suggested a compartmental model with certain tissues constituting a “slow turnover” pool where the turnover times for vanadium might exceed 400 days. Other tissues were suggested to constitute a “fast turnover” pool with vanadium residency of about 100 hours.
In laboratory animals, vanadium mimics insulin (diminishes hyperglycemia and improves insulin secretion) and inhibits the activity of various enzymes. A deficiency of vanadium results in increased abortion rates. A biological role of vanadium in humans has not yet been identified. Therefore, neither an Estimated Average Requirement, Recommended Dietary Allowance, nor Adequate Intake was determined for vanadium.
Foods rich in vanadium include mushrooms, shellfish, black pepper, parsley, dill seed, and certain prepared foods. Myron and coworkers (1977) reported that processed foods contained more vanadium than nonprocessed foods. Byrne and Kosta (1978) also suggested that beer and wine may contribute an appreciable amount of vanadium to the diet. Commodity groups highest in vanadium are grains and grain products, sweeteners, and infant cereals. Analysis of data from the 1984 Food and Drug Administration Total Diet Study (Pennington and Jones, 1987) showed grains and grain products contributed 13 to 30 percent of the vanadium in adult diets. Beverages were also an important source for adults and elderly men (26 to 57 percent). This study also reported that 88 percent of the foods consumed had concentrations less than 2 μg/100 g. Canned apple