Video summary

How To Tell If You Have Vitamin B12 Deficiency (Do These 5 Things)

Main summary

Key takeaways

Wellness and Self-Improvement

Key takeaway

A B12 deficiency can be missed by standard blood tests and may cause potentially irreversible nerve damage. If you’re concerned, take a systematic approach: assess risk, identify symptom patterns, test in the right order, determine the cause, and use treatment matched to the underlying problem.

1) Determine if you have reason to suspect B12 deficiency (risk factors first)

Having a risk factor plus at least one relevant symptom makes testing especially justified (per UK guidance referenced in the summary).

Major risk factors mentioned

  • Age > 50 (age-related decline in stomach acid can prevent B12 release from food proteins)
  • Acid-suppressing medications
    • “-zol” PPIs: omeprazole, lansoprazole, pantoprazole, esomeprazole
    • Older H2 blockers: ranitidine, famotidine
  • Metformin (type 2 diabetes medication)
  • Other possible medication categories (discuss with a clinician)
    • epilepsy meds
    • anxiety meds
    • nerve pain meds
    • gout meds
  • GI surgery or anatomy changes
    • stomach removed (partial/total)
    • gastric bypass / weight-loss surgery
    • small intestine surgery involving the terminal ileum
  • H. pylori infection (can cause chronic stomach lining damage/low acid over time)
  • Autoimmune gastritis / pernicious anemia
  • Low/no animal product intake (plants don’t reliably provide enough B12)
  • Nitrous oxide (“laughing gas”) use
    • can cause functional B12 deficiency even when lab B12 looks normal

2) Use a short symptom set (most actionable patterns)

Instead of vague symptoms, focus on high-signal symptom clusters tied to how B12 affects blood/oxygen delivery and nerve insulation.

The 4 main symptom groups (plus 1 mirror-check)

  1. Fatigue + shortness of breath on exertion

    • Likely mechanism: impaired red blood cell production → less effective oxygen delivery
    • Can mimic anemia, even when obvious anemia isn’t present

  2. Tingling/numbness in hands or feet (often symmetrical)

    • High priority symptom
    • Mechanism: B12 supports myelin insulation; deficiency can cause progressive neuropathy starting in the longest nerves (feet/hands)
    • Clue: usually both sides; one-sided symptoms are less typical

  3. Balance problems / unsteadiness, worse in the dark

    • Mechanism: progression from peripheral nerves to spinal cord proprioception issues
    • Clue: less stable without visual compensation; may involve checking feet while walking

  4. Cognitive/mood symptoms (“brain fog,” memory lapses, losing your train of thought)

    • Can mimic dementia
    • Mechanism: brain wiring insulation + elevated homocysteine + effects on neurotransmitter systems (serotonin/dopamine)

  5. Extra self-check: tongue changes

    • Glossitis: flattened/smooth shiny red tongue with burning/pain
    • Not definitive (can occur with or without B12 issues)

3) Decide how/when to get tested (test in the right order)

Do this before starting supplements

  • Get blood testing before taking B12 supplements (otherwise you may “wash out” results and make interpretation harder).
  • Exception (urgent/emergency context): If there are severe neurologic symptoms (e.g., difficulty walking, intense numbness/tingling) and suspicion is high, clinicians may treat immediately (e.g., injections) because waiting risks harm.

Understand the “gray zone” and what to request

A standard B12 test is only one data point. The UK-style framework described:

  • Below ~180: deficiency
  • ~180–350: indeterminate/gray
  • Above ~350: deficiency unlikely

If results are in the indeterminate range and symptoms/risk fit:

  • Ask about methylmalonic acid (MMA) testing (reflects cellular-level B12 need)
  • Limitation: kidney function can raise MMA, so interpretation should consider kidney results

Tests mentioned

  • Standard B12 (may miss “functional” deficiency)
  • MMA (better for cellular deficiency)
  • Homocysteine (can support diagnosis; logistics/sample handling can complicate)
  • Active B12 (measures the usable fraction; not always routinely offered)

Special case: nitrous oxide users

  • Standard B12 may be misleadingly normal/high because nitrous oxide inactivates B12.
  • Guidance described: prefer MMA and/or homocysteine earlier in suspected cases.

4) Don’t stop at “fixing the number”: find the cause (prevention strategy)

If diagnosed, identify why deficiency occurred so it doesn’t recur.

Cause-finding steps emphasized

  • Intrinsic factor antibody testing (for autoimmune gastritis/pernicious anemia)
    • Positive strongly supports diagnosis
    • Negative does not fully rule it out
  • If needed:
    • additional antibody testing and endoscopy with biopsy
  • Evaluate for celiac disease (can be silent but treatable)
  • Review:
    • medications
    • surgical history
    • antibodies

Long-term consequence highlighted

  • Autoimmune gastritis increases stomach cancer and gastric neuroendocrine tumor risk → may require lifelong monitoring.

Medication guidance (behavioral/productivity tip = don’t self-stop)

  • Often don’t stop necessary meds (e.g., metformin); instead monitor B12.
  • For metformin: the speaker suggests checking B12 periodically (often annually).
  • For acid blockers: some people need them, but long-term use without reassessment is common—discuss ongoing need with a clinician.

5) Match treatment to the underlying cause (treatment strategy)

Treatment depends on whether the issue is absorption failure, diet/temporary causes, or adherence concerns.

Injections vs tablets (what decides which?)

Injections (bypass gut absorption)

  • Used when absorption is the main problem.
  • UK regimen described:
    • No/limited nervous symptoms: 1 mg IM 3x/week for 2 weeks, then every 2–3 months
    • With nervous symptoms: 1 mg IM every other day until improvement stops, then every ~2 months
  • US principle described:
    • cyanocobalamin often weekly for 1 month, then monthly

High-dose oral tablets (can work via small passive absorption)

  • A small fraction (≈1–2%) can absorb without the usual terminal ileum transport mechanism.
  • The speaker cites evidence suggesting tablets can work comparably in some cases.
  • Suggested approach described:
    • For partial/reversible issues: high-dose oral, at least 1 mg/day
    • For lifelong structural absorption failure: injections are likely needed for life
  • Dietary cause → tablets typically default

Timing expectations (self-care planning)

  • Blood markers recover quickly, but
  • Nerve symptoms take longer:
    • fatigue: often improves 2–4 weeks
    • tingling/numbness: often improves 3–6 months, may continue up to 1 year
  • If symptoms have lasted years, improvement may be incomplete.

Monitoring during treatment

  • Monitoring focuses more on symptoms rather than repeatedly rechecking B12 levels (since supplementation/injections raise levels).

6) Practical “what I would do” if your B12 result is “normal” but you feel unwell

If you’re in the indeterminate/gray area and still symptomatic:

  • Return to your clinician with:
    • the exact symptoms + duration
    • applicable risk factors (metformin, PPIs, age, etc.)
  • Ask specifically:
    • Is MMA testing appropriate?
  • If MMA isn’t available:
    • ask whether an empiric trial of treatment is reasonable, and use response to guide next steps
  • If no progress:
    • request a second opinion (other doctor/clinic)
    • private testing can be valid, but results should still be discussed with a clinician rather than treating blindly

Supplement warning

  • Don’t assume B vitamins help if levels are already adequate.
  • The speaker discourages indiscriminate B-vitamin use without evidence and notes supplements can sometimes cause harm.

Presenters / Sources

  • Presenter/source: Dr. Alex (newsletter referenced as dr.alexnewsletter.com; video author/speaker is Dr. Alex)
  • Organization guideline source (UK): NICE (National Institute for Health and Care Excellence)
  • Medical entities mentioned (not as guidance sources): metformin, omeprazole/lansoprazole/pantoprazole/esomeprazole, H. pylori, autoimmune gastritis/pernicious anemia, celiac disease, Crohn’s disease, intrinsic factor antibodies, MMA (methylmalonic acid), homocysteine.

Original video