Can one have excessively high vitamin B12 (cobalamin) levels?

From the Guidelines

Yes, it is possible to have excessively high vitamin B12 levels, which can occur due to excessive supplementation or certain liver diseases. High B12 levels are most commonly seen in people taking high-dose supplements, receiving B12 injections, or those with certain liver diseases that impair the body's ability to regulate B12 storage 1. Symptoms of excessive B12 can include acne, rosacea, dizziness, headache, anxiety, and nausea, though many people with high B12 levels remain asymptomatic. The normal range for B12 in blood tests is typically between 200-900 pg/mL, with levels above this potentially indicating an issue. Some key points to consider:

• High-dose B12 supplementation can lead to elevated levels, and monitoring is essential to prevent potential adverse effects 1.
• Certain liver diseases can impair the body's ability to regulate B12 storage, leading to high levels 1.
• If you suspect your B12 levels are too high, you should consult with a healthcare provider who may recommend reducing supplement intake or investigating underlying conditions.
• It is essential to note that B12 can accumulate in the liver, which is why monitoring levels is crucial when supplementing regularly 1. In terms of treatment, reducing supplement intake or investigating underlying conditions is recommended. Some studies suggest that high-dose B12 supplementation can have adverse effects, such as increasing the risk of stroke in certain populations 1. However, other studies recommend B12 supplementation to reduce the risk of stroke, particularly in patients with diabetic nephropathy 1. Overall, it is crucial to consult with a healthcare provider to determine the best course of action for individual cases of high B12 levels.

From the Research

Causes of Excessively High Vitamin B12 Levels

• High serum levels of vitamin B12, also known as hypervitaminemia B12, can be caused by various factors, including solid neoplasia, acute or chronic hematological diseases, liver disorders, monoclonal gammapathy of undetermined significance, renal failure, and excess vitamin B12 intake 2, 3, 4
• Inflammatory or autoimmune diseases, and transient hematological disorders can also contribute to elevated vitamin B12 levels 2
• A case report found that multiple high doses of vitamin B12 can induce toxicity, resulting in symptoms such as acne, palpitations, anxiety, and insomnia 5

Associations with Diseases

• Hypervitaminemia B12 has been linked to various serious conditions, including malignant diseases, with a study finding a significant association between elevated vitamin B12 levels and solid neoplasia, liver diseases, and acute renal failure 4
• A systematic review found an association between elevated vitamin B12 levels and a higher risk of cancer, with risk ratios ranging from 1.88 to 5.9 6
• Another study found that hypervitaminemia B12 was associated with a 5.7-fold higher risk of hematological disorders in elderly patients 4

Clinical Implications

• Elevated vitamin B12 levels can have clinical implications, including an increased risk of cancer and mortality, although the evidence for the latter is less consistent 6
• A practical approach to managing hypervitaminemia B12 involves identifying the underlying cause and addressing it accordingly 3