Vitamin B12 Evaluator
Metabolic Relevance
B12 is essential for nerve function, DNA synthesis, and energy metabolism. Deficiency can cause neurological problems, fatigue, and cognitive issues — even in the lower part of the "normal" range. Metformin use, vegan diet, and aging all increase deficiency risk.
Recommended testing frequency:
Annually, or every 6 months if on metformin or plant-based diet
Did you know?
Metformin reduces B12 absorption, which can cause up to 30% reduction in levels with long-term use. If you take metformin, consider monitoring B12 more frequently.
Optimal levels are 500-800 pg/mL, which is higher than the lower limit of the laboratory "normal" range (200 pg/mL). Symptoms can occur even at "normal" levels.
Want to understand your result better?
Learn about interpretation, what affects your score, and evidence-based strategies to improve it.
Read the full guideEvidence-Based
This calculator is based on peer-reviewed research validated across thousands of clinical studies.
View scientific references(10)Medical Disclaimer
Why Optimal Thresholds Differ?
Standard Medical
⚠️ Focused on preventing clinical deficiency
Research Consensus
✓ Prevents subclinical neurological effects
Metabolic Optimization
🔬 Accounts for absorption issues and drug interactions