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Clinician’s Corner: Vitamin B-12 (cyanocobalamin)

Now it is time to discuss the one vitamin I see myself recommending more than any other supplement–Vitamin B-12 (cyanocobalamin)

Source of B12: muscle meats, liver & daily products. Not found in vegetables. Vegetarians are at risk.

  • Function: involved in cell division, and recycling of folate. Folate deficiency is observed as a feature of B12 deficiency.  Symptoms of deficiency are reflected in organ systems with rapidly duplicating cells. Vital for cell growth and mitosis.  This includes the hematopoietic system, gastrointestinal tract and neurological systems. Vitamin B12 is required for proper red blood cell formation, neurological function, and DNA synthesis
  • Deficiency: Pernicious anemia: is a megaloblastic anemia. May cause neuropathy.
  • Remember –large doses of folic acid will correct the hematological symptoms, but will allow neurological damage to progress.
  • Decreased production of intrinsic factor: due to pernicious anemia, gastrectomy or bariatric surgery.

Causes of Vitamin B12 deficiency

  • Dietary deficiency of Vitamin B-12 is rare. Noticeable symptoms of a vitamin B12 deficiency can take years to develop. Irritability, weakness, numbness, anemia, loss of appetite, headache, personality changes, and confusion are some of the signs and symptoms associated with very low levels of vitamin B12. True vegans need to supplement B12.
  • Many patients have trouble absorbing B12 from food due to reduced gastric acidity from PPI’s (Prilosec, Nexium and others) or H2RA’s (Zantac, Pepcid, and others) or lack of intrinsic factor. Remember about 5 years ag when we couldn’t get Vitamin B-12 injection due to a manufacturer shortage? Oral supplements can be used since about 1% of oral supplements will be passively absorbed, without gastric acid or intrinsic factor.
  • Metformin long term will deplete vitamin B12 levels. The challenge becomes that Vitamin B12 deficiency may look like diabetic peripheral neuropathy, with numbness and tingling in the feet and hands.  I have reversed at least 6 patients “neuropathy” by recommending Vitamin B12 1,000mcg per day.  What they really had was a B12 deficiency, and not neuropathy!

**Note: biological half-life of B12 is 1 year, therefore more than 2 years must elapse after a complete cessation of B12 intake before clinical manifestations of deficiency are apparent.

Noticeable symptoms of a vitamin B12 deficiency can take years to develop. Irritability, weakness, numbness, anemia, loss of appetite, headache, personality changes, and confusion are some of the signs and symptoms associated with very low levels of vitamin B12.

ORAL VITAMIN B12 standard dosing

  • Begin with 1000mcg per day.  (because of poor absorption, about 5mcg/dose is actually absorbed)

INJECTABLE VITAMIN B12 standard dosing

  • Cyanocobalamin is commonly available as 1000mcg /ml injections
  • Start with 1000mcg IM every day for 1 week. Then 1000mcg IM weekly for 4 weeks, then 1000mcg IM monthly for prevention.
  • Recommend injectable B12 for patients with more severe deficiency or those who may not absorb it due to diarrhea, vomiting, or bowel resection.
  • Vitamin B12 injections are also recommended for patients with GI- bypass surgery (for weight loss).
  • Vitamin B12 depletion is also implicated in patients with tinnitus (ringing in the ears); supplementation might be of benefit. Poor vitamin B-12 and folate status may be associated with age-related auditory dysfunction.

Anyone taking any acid suppressing drugs, metformin or any stomach surgery are excellent candidates for vitamin B12 therapy.

Have a great day on the bench!

Pete Kreckel   Thompson Pharmacy Broad Ave