Low B12: What It Means and What to Do Next
Low B12 (below 200 pg/mL, or suboptimal below 500 pg/mL) causes fatigue, brain fog, numbness, tingling, and depression. B12 deficiency is common in vegans, older adults, and people taking metformin or acid reflux medications. It is easily correctable with supplementation or injections.
What Causes Low Vitamin B12?
Vegan/Vegetarian Diet
B12 is found almost exclusively in animal products. Plant-based eaters must supplement.
Aging
Stomach acid production decreases with age, reducing B12 absorption. Up to 20% of adults over 60 are deficient.
Pernicious Anemia
An autoimmune condition that destroys intrinsic factor, a protein required for B12 absorption in the gut.
Medications
Metformin (diabetes), PPIs (acid reflux), and H2 blockers all reduce B12 absorption over time.
Gastrointestinal Surgery
Gastric bypass and other GI surgeries reduce the absorption area for B12.
Associated Symptoms
What to Do Next
1. Retest to confirm
A single abnormal result should be confirmed with a repeat test. Temporary factors like stress, illness, or medications can affect results.
2. Related tests to consider
3. When to see a doctor
If your Vitamin B12 is significantly abnormal, if you have severe symptoms, or if repeated results confirm the abnormality, consult a healthcare professional for appropriate evaluation and treatment.
Related Conditions
Frequently Asked Questions
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This page is for informational purposes only and does not constitute medical advice. Consult a healthcare provider for interpretation of your results.
Content reviewed for accuracy by the JustLabs editorial team.