I’m kicking off the Micronutrients and Macronutrients with SIBO series with Vitamin B12 and SIBO.

In 2014 when I was first diagnosed with SIBO, I was so deficient in it that I did weekly B12 injections to my stomach. (Insert sarcasm) It was so much fun that I don’t ever want to have you to go through the same. (My latest testing results showed that I am 14% above average with my B12 stores, FYI.)

know that if you have SIBO now (or have yet to be diagnosed) a Vitamin B12 deficiency is very likely.

And hence, this might be a very beneficial post for you.

Vitamin B12 and SIBO

Click HERE to save the Vitamin B12 and SIBO information for later.

Vitamin B12 and SIBO Methylcobalamin vs Cyanocobalamin agutsygirl.com #b12 #vitaminb12 #methylcobalamin #SIBO

A common complication of bacterial overgrowth is cobalamin (vitamin B12) deficiency.

Patients with normal intestinal enteric flora rely on gastric intrinsic factor to bind to vitamin B12 to permit absorption in the ileum.

Chris Kresser states, 

Although rates of B12 deficiency are much higher in vegetarians and vegans than in omnivores, that doesn’t mean it’s rare in omnivores. According to a study, approximately 1 in 20 omnivores are B12 deficient. In my practice I’d estimate the rate at closer to 1 in 15, possibly because I see a lot of people with gut problems and that is one of the risk factors for B12 deficiency.

Vitamin B12 deficiency occurs in four stages, beginning with declining blood levels of the vitamin (stage I), progressing to low cellular concentrations of the vitamin (stage II), an increased blood level of homocysteine and a decreased rate of DNA synthesis (stage III), and finally, pernicious anemia (stage IV). 

What is Vitamin B12?

Vitamin B12, also known as cobalamin, is a water-soluble vitamin required for many reactions in your body as well as for the health of your nerves, red blood cells, and DNA.

Its most important role is as a methyl group donor, which is a crucial step in many of our main detoxification pathways.

Methylcobalamin vs Cyanocobalamin

There is so much talk about methylcobalamin vs cyanocobalamin.

So how do they differ, and which is the superior form for you?


Cyano B12 is a cheap, synthetic, slightly-toxic, inactive form of B12 that is made with a cyanide donor and is used commercially.

It is the most stable form, because the cyanide molecule has the greatest attraction to the cobalamin and protects it from extreme conditions (like high temperatures).

However, it doesn’t absorb well and requires methyl groups to detoxify it.

When cyano B12 does absorb, it converts to hydroxocobalamin (hopefully discarding of the cyanide in the process) and then to methylcobalamin and adenosylcobalamin. When taken orally, absorption of this form is drastically reduced if you have any gastric acid problems. (Source.)

Vitamin B12 and SIBO www.sarahkayhoffman.com deficiency #guthealth #healthyliving #b12 #SIBO

Vitamin B12 Methylcobalamin

Methylcobalamin, the kingpin, one of the two active, natural forms of B12.

It helps reduce homocysteine concentrations and generates SAMe (S-adenosyl methionine), the most important methyl donor in your body, supplying methyl groups for crucial chemical reactions to help maintain your health.

Where methyl B12 shows its greatest utility is with people suffering form degenerative neurological symptoms, where it’s often the only promising treatment.

It bypasses several potential issues in the absorption cycle and helps relieve or completely reverse symptoms. (Source.)

Why are people with SIBO deficient in Vitamin B12?

Those with digestive disorders, in general, are more susceptible to a Vitamin B12 deficiency because typically they are losing a lot of nutrients (both micro and macro) via the passing of too much stool. 

A Vitamin B12 deficiency affects those with SIBO oftentimes because they produce less stomach acid. In order to convert vitamin B12 properly, adequate stomach acid is critical.

Those with SIBO (and the general population as a whole) are also affected due to:

  • intestinal dysbiosis
  • leaky gut and/or gut inflammation
  • atrophic gastritis or hypochlorhydria (low stomach acid)
  • pernicious anemia (autoimmune condition)
  • medications (especially PPIs and other acid-suppressing drugs)
  • alcohol
  • exposure to nitrous oxide (during surgery or recreational use) 

(Source: Chris Kresser’s ADAPT Program)

What are B12 deficiency symptoms?

Click HERE to save these symptoms for later.

Vitamin B12 and SIBO agutsygirl.com IBS #sibo #guthealth #b12

According to Dr. Axe, here is a list of Vitamin B12 deficiency symptoms:

  • Constantly feeling tired or chronic fatigue
  • Muscle aches and weakness
  • Joint pain
  • Difficulty breathing or shortness of breath
  • Feeling dizzy
  • Poor memory
  • Inability to concentrate well
  • Mood changes, like increased depression and anxiety
  • Having abnormal heart problems, such as palpitations
  • Poor dental health, including bleeding gums and mouth sores
  • Digestive problems like nausea, diarrhea or cramping
  • A poor appetite
  • A more serious deficiency can also cause a form of anemia called pernicious anemia, a serious condition that can cause memory loss, confusion and even long-term dementia

How to recover from Vitamin B12 deficiency?

Vitamin B12 and SIBO 3 ways to recover agutsygirl.com #b12 #sibo #vitaminb12

According to Chris Kresser,

B12 is the only vitamin that contains a trace element (cobalt), which is why it’s called cobalamin. Cobalamin is produced in the gut of animals. It’s the only vitamin we can’t obtain from plants or sunlight. Plants don’t need B12 so they don’t store it.

Even still, I was eating meat and was severely B12 deficient.

This goes beyond simply eating meat.

Recovering from a Vitamin B12 deficiency could mean any or all of the following things:

1. Vitamin B12 Injections

“As always, adequate treatment depends on the underlying mechanism causing the problem. People with pernicious anemia or inflammatory gut disorders like Crohn’s disease are likely to have impaired absorption for their entire lives, and will likely require B12 injections indefinitely. This may also be true for those with severe B12 deficiency causing neurological symptoms.” (Chris Kresser’s ADAPT Program.)

B Complex Vs B12 Injections agutsygirl.com #bvitamin #b12

We have an entire post on agutsygirl.com regarding B Complex and B12 injections.

If you are interested in learning more, click the button below.

2. Vitamin B12 Supplementation

“Cyanocobalamin is the most frequently used form of B12 supplementation in the US. But recent evidence suggests that hydroxycobalamin (frequently used in Europe) is superior to cyanocobalamin, and methylcobalamin may be superior to both – especially for neurological disease.” (Chris Kresser’s ADAPT Program.)

Best Vitamin b12 supplement

Nourish Plus, the primal multivitamin from A Gutsy Girl’s supplement line was formulated with IBS and IBD top of mind.

The daily dose of Vitamin B12 contained within Nourish plus is 8333% daily value (200mcg). Furthermore, it’s the superior form of B12, methylcobalamin (vs cyanocobalamin).

Use code ‘AGUTSYGIRL’ at checkout to save 15% off your entire purchase.

Nourish Plus agutsygirl.com gut health multivitamin #multivitamin

3. Eating B12 Rich Foods

Here are some foods high in B12:

  • liver
  • clams
  • oysters
  • mussels
  • fish eggs
  • octopus
  • fish
  • crab and lobster
  • beef
  • lamb
  • cheese
  • eggs

Yes, those are all animal-based foods.

As it relates to Vegetarian sources of B12, Chris Kresser states, “A common myth amongst vegetarians and vegans is that it’s possible to get B12 from plant sources like seaweed, fermented soy, spirulina and brewers yeast. But plant foods said to contain B12 actually contain B12 analogs called cobamides that block intake of and increase the need for true B12. My intention here is not to bash vegetarian and vegan diets. (I was a macrobiotic vegan myself at one point, for crying out loud!)

(This is another reason I’m not entirely confident anymore that you can heal the gut strictly on a Vegetarian diet.)


Supplements, including the B12 ones listed above, are oftentimes in measurements: mg and mcg. 

So what’s the difference between mg vs mcg?

  • MG = milligram
  • MCG = microgram

Therefore, conversions look like this:

1 milligram (mg) is equal to 1000 micrograms (mcg).

How are your Vitamin B12 levels?

Track your B12 levels and signs/symptoms of deficiency via the 90-day gut healing journal.

If you enjoyed this post, you might also enjoy:

  1. Micronutrients and Macronutrients with SIBO
  2. Reasonable SIBO
  3. Vitamin C for Gut Healing


Vitamin B12 and SIBO www.sarahkayhoffman.com #guthealth #healthyliving #b12 #SIBO
Vitamin B12 and SIBO www.sarahkayhoffman.com deficiency symptoms #b12 #guthealth #SIBO

Similar Posts


  1. Dear maam I am vegan, due to b12 deficiency. I want to start non veg. Please tell me how frequently i should eat non veg, what quantity and for how much period.

  2. Thanks for this Sarah. I hope you have a great time on your vacation. I have been having some very similar symptoms like the ones mentioned in this article. I’m going to look into it.

  3. My son has/had SIBO. His B12 was extremely elevated. His doctor said this was a sign of SIBO. I’m not sure exactly why, I think some bacteria produce B12?

    1. I’d also love to know. This is the first I’m hearing about B12 and my son has neurological issues and chronic SIBO that is incredibly difficult to treat

  4. Injections , supplementation never raise in my brother-in-law. He definitely has neurological symptoms with loss of memory , not being all there and fatigue .
    Any suggestions?

  5. I have several symptoms of SIBO. Also anemia and b12 deficiency. How would you recommend being tested for SIBO as my doctor seems to think it isn’t real or isn’t my issue. I feel confident it is could be. I have developed food allergies and Chronic rosacea. Plus I have developed extreme dark circles under my eyes with no explanation. I need help with being tested. Thank you!

  6. Isn’t it lovely that she doesn’t reply? It’s sad to lead us this far into the water but not let us in your boat! I was really excited about your blog and the similarities between our condition but not so much anymore.

    1. Karen – You don’t have to follow along or get any of the thousands of words, research, and information I provide here to people – FREE of charge. I have a thousand comments that haven’t been responded to yet, but I do my best to keep up.

Leave a Reply

Your email address will not be published. Required fields are marked *