Vitamin B12 and bariatric surgery - advice during COVID-19

02 Apr 2020

People, who have had bariatric surgery procedures such as sleeve gastrectomy, Roux-en-y gastric bypass, duodenal switch, one anastomosis (mini) gastric bypass, single anastomosis duodenal ileal switch (SADIS), have reduced absorption of vitamin B12 and increased risk of developing vitamin B12 deficiency.

Vitamin B12 deficiency may go undetected and is masked by folic acid. Untreated vitamin B12 deficiency may result in subacute combined degeneration of spinal cord or irreversible neuropathy, which may occur in the absence of megaloblastic anaemia.

Consequently, the recommended treatment regimen to avoid deficiency is an intramuscular vitamin B12 injection every three months. Some people require more frequent injections and would usually be guided by specialist hospital colleagues.

As a result of pressures on services, and the requirement of vulnerable groups to self-isolate, people are unable to access timely vitamin B12 injections. This is causing anxiety for many. The British Obesity and Metabolic Surgery Society (BOMSS) recommend the following as an interim measure:

For people who have had bariatric procedures (see opening paragraph) which affect vitamin B12 absorption:

  • In those people with recent or a history of suggestive neurological symptoms, continue with scheduled 3 monthly vitamin B12 injections if possible; however, we recognise the importance of self-isolation. An alternative would be to prescribe oral cyanocobalamin 1000 micrograms/day
  • For those people without a history of suggestive neurological symptoms, prescribe oral cyanocobalamin 1000 micrograms/day
  • If prescription of oral cyanocobalamin is not possible, advise people to buy oral vitamin B12 over the counter (see below suggestions)
  • Recommence three monthly vitamin B12 injections within 3 months or earlier if possible


  • This is an interim arrangement.
  • Intramuscular vitamin B12 injections should start again as soon as practical as vitamin B12 levels may decrease on oral supplements.
  • People who are post-bariatric surgery should adhere to all their vitamin and mineral medications as per the latest recommendations by their specialists, as vitamin and mineral deficiencies can have adverse impact on their immunity, predisposing them to infections.

NICE Clinical Knowledge summary: Anaemia - vitamin B12 and folate deficiency.

Where can I buy oral vitamin B12?

BOMSS, Royal College of General Practitioners and the British Dietetic Association do not endorse any particular brand of oral supplementation, however patients may wish to source oral vitamin B12 as below. Details are correct at the time of writing.
Note the symbol for micrograms is μg and this may be used on some ingredient lists:

  • Holland and Barrett
    These are available to order online or by telephone. By telephone, call 0330 058 2025 and select 'option 0'. Opening times for calls are 8:30am - 8:00pm Monday to Friday, 9:00am - 5:00pm on Saturday and 10:00am - 5:00pm Sunday
    Free standard delivery on orders over £25 otherwise £2.99 for delivery

    Vitamin B12 100 Tablets 500microgram - take two daily
    Timed Release Vitamin B12 100 Tablets 1000 micrograms - take one daily
    Solgar Vitamin B12 1000microgram 100 Nuggets - take one daily
  • Myprotein

    £3.99 delivery charge
    Vitamin B12 1000microgram 60 tablets -one daily