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Vitamin B12


Vitamin B12 / Cobalamin / Cyanocobalamin

Vitamin B12, also known as Cobalamin or Cyanocobalamin, is an extremely important water soluble vitamin necessary for proper neurological function and red blood cell formation that absorbed in the terminal ileum (the last part of the small intestines prior to the large intestine). Vitamin B12 deficiency is very common in people with Crohn's Disease and everyone with Crohn's Disease should have their vitamin B12 levels tested and tracked as deficiency can result in serious symptoms and permanent damage.

Some doctors do not test vitamin b12 levels directly but mistakenly only look for signs of macrocytic (megaloblastic) anemia which can be masked by high folic acid intake and is NOT present in upwards of 25% of cases.[1][4]

Vitamin B12 deficiency leads to a serum build-up of methylmalonic acid and homocysteine. Because of this, Homocysteine and Methylmalonic acid levels are considered more reliable indicators of B12 deficiency than the concentration of B12 in blood. Upwards of 50% of patients with vitamin B12 levels between 200400pg/ml (147.6-295.2pmol/L) will have a vitamin B12 deficiency on the basis of elevated levels of homocysteine and methylmalonic acid.[7] Other studies and papers suggest the same with slight variances on the levels.[11], [12], [13], [14], [15], [16]

Symptoms of Vitamin B12 Deficiency:

Premature grey hair
Tinnitus [2]
Subacute combined degeneration (SCD) of the spinal cord
Rapid heartbeat and breathing
Pale skin
Sore tongue
Easy bruising or bleeding including bleeding gums
Optic neuropathy[9]
Stomach upset
Weight loss, diarrhea
Tingling or numbness in fingers and toes (peripheral neuropathy) Megaloblastic anemia
Difficulty walking
Mood changes or depression
Memory loss
Decreased sense of smell and taste[17]

B12 deficiency also causes folate to be trapped in the body in an unusable form leading to symptoms of folate deficiency [1] and on the other side of the coin, folate deficiency can cause increases in B12 analogues (inactive B12) and decreases in cobalamin (active B12).

Anatomy of Absorption:

In order for vitamin B12 to be successfully absorbed, haptocorrin (R-protein or R-factor) must first be secreted in the mouth and by the stomach's parietal cells and bind to the vitamin B12 in the stomach when hydrochloric acid and pepsin separate the B12 from protein. The stomach's parietal cells must excrete intrinsic factor and the pancreas must secrete pancreatic protease which separates the haptocorrin and B12 in the duodenum, then the intrinsic factor must bind there to the B12. Recirculated B12 is also released at this point via the bile duct. Then the cubam receptors must absorb the B12 in the terminal ileum. Once absorbed, vitamin B12 binds to transcobalamin II and becomes holotranscobalamin (active vitamin B12) and is transported throughout the body. Those with Crohn's Disease have potential issues at each point, especially the terminal ileum which is the most commonly inflamed area for people with CD.[8]

In addition, absorption issues can be caused by proton pump inhibitors, H2 blockers, anti seizure medications, Colchicine, Metformin and oral contraceptives[3][10]. Elderly are at even higher risk due to lower decreased stomach acid which readies dietary B12 to be bound by intrinsic factor. H.pylori infection has been incriminated to cause B12 malabsorption among adults. About 1-2% of large oral doses of vitamin B12 passively diffuses into the bloodstream from the small intestine.[8]

In the event oral supplementation of Vitamin B12 is not optimal, there is a nasal spray available from Strativa Pharmaceuticals called Nascobal (Cyanocobalamin, USP). It is a once - weekly dosing specifically for persons who are unable to absorb enough Vitamin B12 orally. For more information on Nascobal: Nascobal Website[5] and a Nascobal Coupon: Nascobal Coupon[6].

Recommended Daily Intake:

This is dependent upon many factors. One should first have their levels tested and supplement based upon those results under the supervision of their physician. supports recommendations which suggest patients (and especially patients with IBD) strive to get their vitamin B12 levels significantly above the accepted laboratory reference range of ~200pg/ml (147.6 pmol/L) to at least 500pg/ml (369pmol/L) in an effort to lower your level of methylmalonic acid [3][7].

Natural Sources of Vitamin B12:

The chart below provides sources of vitamin B12:

While vitamin B12 supplementation is generally safe, there are some safety measures to be aware of first. Potassium levels should be monitored closely while taking high doses of B12, eating a banana or peanut butter may help increase adequate potassium levels.

Supplementation of Vitamin B12 may reduce levels of other B Vitamins and can lead to imbalance [3]. Consult your physician about adding a B Complex Vitamin to your Vitamin B12 therapy.


There is little evidence for toxicity and no upper limit has been set.[8]

Elevated Levels of Vitamin B12

Elevated levels of vitamin B12 can be due to liver disease or injury. Serum levels rise while tissue levels are depleted and as such, methylmalonic acid and homocysteine levels should be tested as there can be actual B12 deficiency.[8]


For More Information on Vitamin B12 Deficiency


[pos]11a[/pos][11] Swain R J Fam Pract., 1995; 42: 595-61.
[pos]12a[/pos][12] Hvas AM et al., Ugeskr Laeger., 2003; 165: 1971-6.
[pos]13a[/pos][13] Schneede J Scan J Clin Lab Invest., 2003; 63: 369-376.
[pos]14a[/pos][14] Klee G, Clin Chem., 2000; 46; 8(B): 1277-1283.
[pos]15a[/pos][15] Hermmann W et al Curr. Drug Metab. 2005; 6 : 47-53
[pos]16a[/pos][16] Snow CF Arch Intern Med., 1999 ;159 :1289-98.

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05-27-2015, 11:53 AM   #1
Join Date: May 2015
For those struggling with B12 deficiency, I recently heard about a new oral prescription alternative to the injections called Eligen B12. I recently read that it works even if you don't have intrinsic factor (so even if you don't have normal gut absorption). Apparently it came out a month or two ago. Has anyone heard of it or tried it??
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