Vitamin B12 Deficiency



Vitamin B12 deficiency a complication following Bariatric Surgery

It has recently been shown that vitamin B12 deficiency is an unforeseen complication of Bariatric surgery. There are significant stores of vitamin B12 in the liver, and so onset of symptoms following Bariatric surgery may take several years. Whilst some of the symptoms/consequences of vitamin B12 deficiency may be reversible, some are not. Studies have shown that serum vitamin B12 deficiency had developed in 33.3% of patients at 2 years post surgery. In a 2-year follow-up study, 46.6% of the patients had already developed anemia which increased to 63.6% at 3 years. Hence it is recommended that high dose supplementation with  vitamin B12 be initiated as soon as possible after surgery. Procedures that have definitely been shown to cause deficiency include Roux-en-Y gastric by-pass and biliopancreatic diversion with duodenal switch, and potentially Laparoscopic sleeve gastrectomies (LSG) (Sherf-Dagan et al,  2017; Ponsky et al, 2005; Avarez-Leitte, 2004; Sally and Stabler, 2013; Smelt et al, 2015).


Vitamin B12 deficiency due to altered absorption

The absorption of vitamin B12 requires binding to Intrinsic Factor that is released from gastric parietal cells, low gastric pH to help in the release of vitamin B12 from food, and absorption in the ileum. Any or all of these factors can be disrupted after bariatric surgery..


Vitamin B12 deficiency leads to Neurological complications                

While it is well known that anaemia is a direct consequence of very low levels of vitamin B12 earlier, during the development of vitamin B12 deficiency It has been shown that early in vitamin B12 deficiency demyelination of the autonomic nervous system may occur.  Vitamin B12 has a vital role in neuronal development, particularly in myelinogenesis. Neurologic symptoms commonly seen with B12 deficiency include paresthesias, weakness, decreased reflexes, spasticity, ataxia, position and vibratory sense loss, incontinence, loss of vision from optic nerve injury, macular degeneration, dementia, psychosis, and altered mood. Severe autonomic symptoms may also sometimes occur. More recently there have been examples of vitamin B12-deficiency following bariatric surgery causing optic neuropathy and associated loss of visual acuity (Sawica-Pierko et al, 2014).


Vitamin B12 Supplementation

It is very important that  Vitamin B12supplementation is started before any of the potential symptoms develop. Due to the compromised nature of the intestine of the Bariatric surgery patient, normal multi-vitamin supplements have little effect and so high dose supplementation is required. Normal vitamin supplements do NOT provide sufficient vitamin B12 to over-come loss following surgery. Supplementation with folate, thiamine, vitamin D, vitamin E and copper may also be required.


Vitamin B12 in Supplements

The use of vitamin B12 in supplements for treatment of deficiency is controversial with many studies showing no benefit being obtained from standard supplements as the amount of vitamin B12 in the standard supplements is too low and because the normal intrinsic factor-mediated uptake system is compromised., Furthermore, studies with high dose oral supplements with cyanocobalamin were not effective in restoring normal levels of homocysteine, in reversing clinical signs of deficiency, or in maintaining normal levels of serum vitamin B12 once supplements were ceased. Furthermore studies have shown that  oral supplements given to VB12 deficient vegan mothers who have undergone bariatric surgery were NOT effective in restoring VB12 levels in new born babies. It is recommended that those who have had bariatric surgery take a daily dose of at least 500 ug of vitamin B12 (Sherf-Dagan et al, 2017)


Vitamin B12 Injections

Vitamin B12 injections can be administered in cases of insufficiency if it is diagnosed, however they are generally not administered post-partum to women who have had Bariatric surgery, nor are they regularly administered to most people who have had Bariatric surgery, until there is a problem.


Topical Vitamin B12

A topical form of vitamin B12 has recently been developed which  is easy to administer, contains the natural form of the vitamin and has the added advantage of providing a prolonged release of the vitamin over several days.  This topical formulation is able to provide a much higher dose of vitamin B12 than oral supplements and is ideally suited for people who have undergone bariatric surgery.


Further information on Vitamin B12supplementation

Sawicka et al. Nutritional optic neuropathy following bariatric surgery. Wideochir Inne Tech Maloinwazyine 2014 9: 662-6

Sherf-Dagan et al. Health and nutritional status of vegetarian candidates for Bariatric surgery and practical recommendations. Obes Surg 2017

Ponsy et al. Alterations in gastrointestinal physiology after Roux-en-Y gastric surgery. J Am Coll Surg 2005 201:125-31

Alvarex-Leitte Nutrient deficiencies secondary to bariatric surgery Curr Opin Clin Nutr Metab Care 2004 7:569-75

Salle And Stable Vitamin B12 deficiency - clinical practice N Eng J Med 2013 368: 149-60

Smelt et al Improving Bariatric patient aftercare outcome by improved detection of a functional vitamin B12 deficiency Obes Surg 2015


Further information on vitamin B12 and deficiency states, as well as potential use of vitamin B12 can be found by following the following links:


For information on topical vitamin B12, contact us.



Copyright © 2018 All Rights Reserved. 
The statements on this site compose a compendium of generally recognized signs of vitamin B12 deficiency, and problems that can then ensue They also are formulated from a summary of relevant scientific publications. In addition they may contain some forward looking statements of a general nature.
Reproduction in whole or in part in any form or medium without express written permission is prohibited