blood tests show high b12 but imnot taking any supplements
High vitamin B12 is a symptom of an underlying illness that causes the amount in your blood to increase. For example, a damaged liver may release the vitamin out of storage and into the blood. In early stages, illnesses associated with high vitamin B12 often have generic symptoms, such as fatigue and loss of appetite.itamin B12 does not accumulate to toxic levels. Consuming large quantities does not cause side effects or high levels in your system, whether you get it through food or from taking high-dose supplements.