Vitamin B12 deficiency is surprisingly common, affecting up to 15% of the population. Yet it can be missed because symptoms can develop gradually and mimic other conditions.
Why B12 Matters
B12 is essential for:
- Energy production
- Red blood cell formation
- Nerve function and myelin production
- DNA synthesis
- Mood regulation
- Brain health and cognition
Who May Be at Risk?
- Vegetarians and vegans (B12 is primarily in animal foods)
- Adults over 50 (reduced stomach acid can impair absorption)
- People taking metformin, PPIs, or H2 blockers
- Those with celiac, Crohn's, or other GI conditions
- Post-bariatric surgery patients
Symptoms B12 Deficiency Can Cause
- Fatigue and weakness
- Brain fog and memory issues
- Numbness or tingling in hands/feet
- Depression and mood changes
- Glossitis (swollen tongue)
- Difficulty walking
- Pale or jaundiced skin
Testing for B12
Serum B12
Standard test, but may miss functional deficiency. Optimal may be >500 pg/mL.
Methylmalonic Acid (MMA)
May be a more sensitive marker that can rise when B12 is low at the cellular level.
Homocysteine
Elevated levels may point to B12 or folate deficiency.
Important Note
Neurological damage from B12 deficiency can be irreversible if not caught early. If you have symptoms, don't wait to get tested.
References
- Stabler, S. P. (2013). Clinical practice: vitamin B12 deficiency. New England Journal of Medicine, 368(2), 149-160. PMID 23301732
- Allen, L. H. (2009). How common is vitamin B-12 deficiency? American Journal of Clinical Nutrition, 89(2), 693S-696S. PMID 19116323
- Langan, R. C., & Goodbred, A. J. (2017). Vitamin B12 deficiency: recognition and management. American Family Physician, 96(6), 384-389. PMID 28925645
