Interestingly, cobalt deficiency has not been reported in humans. Instead, the phenomenon of low B12 due to decreased intrinsic factor is encountered. Pernicious anemia occurs when autoantibodies against intrinsic factor or parietal cells leads to an intrinsic factor deficiency. This then leads to malabsorption of vitamin B12 and subsequent megaloblastic anemia. Note that this deficiency is not due to cobalt deficiency but rather to a deficiency of intrinsic factor.
Cobalt is not highly toxic, but acute exposures can result in pulmonary edema, nausea, vomiting, hemorrhage, and kidney failure.
