How can you remove excess B12 from the body to reduce B12 levels? Well, there’s a bigger issue present here other than the B12 itself. If your blood test came up with high B12 levels, this normally points to an underlying condition that could be serious:
The aetiological profile of high serum cobalamin predominantly encompasses severe disease entities for which early diagnosis is critical for prognosis. These entities are essentially comprised of solid neoplasms, haematological malignancies and liver and kidney diseases. This review reflects the potential importance of the vitamin B12 assay as an early diagnostic marker of these diseases. A codified approach is needed to determine the potential indications of a search for high serum cobalamin and the practical clinical strategy to adopt upon discovery of elevated cobalamin levels. While low serum cobalamin levels do not necessarily imply deficiency, an abnormally high serum cobalamin level forms a warning sign requiring exclusion of a number of serious underlying pathologies.
The pathophysiology of elevated vitamin B12 in clinical practice
Treatment of High B12 Levels
Considering the above, the treatment for high vitamin B12 levels should really treat the underlying condition. Once you cure that condition, B12 levels should return to the normal range. The B12 itself is harmless, and excess B12 naturally flushes out of your system. But high levels in the blood should concern you, because something is causing the B12 to be released from its stores into the blood.
It could be cancer destroying healthy cells (releasing stored B12 back to the blood), a malfunctioning liver that can no longer store the B12, kidney issues, or an increased production of the transport protein haptocorrin, to which B12 in the blood binds:
Elevated levels of serum cobalamin may be a sign of a serious, even life-threatening, disease. Hematologic disorders like chronic myelogeneous leukemia, promyelocytic leukemia, polycythemia vera and also the hypereosinophilic syndrome can result in elevated levels of cobalamin. Not surprisingly, a rise of the cobalamin concentration in serum is one of the diagnostic criteria for the latter two diseases. The increase in circulating cobalamin levels is predominantly caused by enhanced production of haptocorrin. Several liver diseases like acute hepatitis, cirrhosis, hepatocellular carcinoma and metastatic liver disease can also be accompanied by an increase in circulating cobalamin. This phenomenon is predominantly caused by cobalamin release during hepatic cytolysis and/or decreased cobalamin clearance by the affected liver. Altogether it can be concluded that an observed elevation of cobalamin in blood merits the a full diagnostic work up to assess the presence of disease.
SIGNIFICANCE OF ELEVATED COBALAMIN (VITAMIN B12) LEVELS IN BLOOD
So, go and have the necessary tests done.
The only exception: If you take a B12 supplement regularly, then high blood levels of B12 will be completely normal. Nothing to worry about.
Decrease B12 Levels Anyway?
If you’re still obsessed over lowering your B12 levels, just know that vitamin B12 is water-soluble. Any excess in the blood is released in the urine within hours. It really doesn’t take much long for excess B12 to flush out of your system.
There are no toxicity levels, and you can’t overdose on B12. In life-threatening cases of cyanide toxicity, 5,000,000µg of B12 is injected as treatment. Blood levels rapidly rise to 560,000,000pmol/L, and if necessary, treatment is repeated for a total of 10,000,000µg of B12. This is more than 4 million times the recommended daily intake, yet still there’s no toxicity. Quite the opposite, it actually clears the body of the cyanide toxicity! The B12 levels in the blood will return to normal once the excess has been urinated out.

Even in kidney dialysis patients with polyneuropathy, high levels of B12 incur no side effects. In Japan, such patients received 5,000µg of B12 three times a week for half a year. Because of their bad renal clearance, the B12 remained in the blood, and levels rose from an average of 422 pmol/L to 54 000 pmol/L. No side effects were recorded.
Our Point
If you supplement, you’re going to have high levels of vitamin B12 around the clock. Don’t worry about it. It is harmless. Drink enough water, and any excess of B12 will flush out of your system through the urine, within a matter of hours.
If, however, you do not supplement and still show elevated B12, then do the necessary tests to see what underlying disease is causing this. Treat the disease, and you’ll naturally treat the elevated B12. All in all, don’t worry about how to reduce B12 levels, but instead worry about how to fix whatever disease is causing it to be elevated.
Best of luck.