Vitamin B-12 (cyanocobalamin)—the pharmacist's favorite supplement.
Source of B12: muscle meats, liver & dairy products. Not found in vegetables. Vegetarians are at risk.
Function: involved in cell division and rapidly growing cells in the body. This includes the blood forming system, gastrointestinal tract, and nervous system.
- Large blood cell anemia.
- Untreated Vitamin B12 deficiency may cause neuropathy. Remember that large doses of folic acid will correct the anemia but will allow nervous system damage to progress.
Vitamin B12 is bound to protein in meats and dairy products and is released by the activity of stomach acid. When synthetic vitamin B12 is added to fortified foods and dietary supplements, it is already in free form and does not require this separation step. Decreased vitamin B12 absorption can be due to reduction in stomach size, as in 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, however fortified breakfast cereals are a readily available source of vitamin B12 with high bioavailability.
- Many patients have trouble absorbing B12 from food due to reduced gastric acidity from drugs that suppress stomach acid such as Prilosec, Nexium, Pepcid and others. Oral supplements can be used since about 1% of oral supplements will be absorbed, without gastric acid.
- 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. Patients may have a B12 deficiency, and not neuropathy!
Because Vitamin B-12 is stored in the liver, more than 2 years must elapse after a complete stopping of B12 intake before symptoms may occur. 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 absorbed). Sublingual tablets or gels cost more but are not any better than regular tablets.
- Recommend injectable B12 for patients with more severe deficiency or those who may not absorb it due to diarrhea, vomiting, or bowel surgery.
- Vitamin B12 injections are also recommended for patients with weight loss surgery.
- 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 hearing loss.
Anyone taking any acid suppressing drugs, metformin or any stomach surgery are excellent candidates for vitamin B12 therapy.
Your Nickman’s pharmacist is a great resource for information on vitamins, especially when deficiency can be caused by prescription products. Ask us now!