A vitamin B12 level of 140 pg/ml is considered low, as the normal range for serum vitamin B12 is roughly 200 to 900 pg/ml¹. Methylcobalamin, a form of vitamin B12, is often recommended for improving B12 status, especially in cases of deficiency.

Supplementing with 1500 mcg of methylcobalamin daily could potentially help raise your B12 levels over a period of 20 days; however, the response can vary based on several factors including absorption rates and the underlying cause of your deficiency¹. Typically, for deficiencies, oral supplementation can range from 1000 to 2000 mcg daily for a few weeks to months, depending on the severity¹.

Here are some general suggestions:

1. Consult Health Professionals: It is important to consult with a healthcare provider for personalized advice, as they can consider your specific health needs and any potential interactions with medications you may be taking.

2. Monitor Levels: Regular monitoring of your B12 levels during supplementation can help assess how well your body is responding to treatment and prevent potential overdosing.

3. Address Underlying Causes: Identify and address any underlying issues contributing to the deficiency, such as dietary intake, absorption disorders (like pernicious anemia), or medication interactions.

Without more context or personal health information, these are general guidelines. It's crucial to adjust supplementation under medical supervision to ensure efficacy and safety.

Footnotes

1. National Institutes of Health, "Vitamin B12 - Fact Sheet for Health Professionals," Office of Dietary Supplements. ↩ ↩² ↩³