Pernicious Anaemia Society
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B12 and Thyroid

Here on PAS and over on Thyroid UK (and, I assume, in most related groups) we see a considerable number of people who actually have, or suspect they have, aspects both of thyroid and of B12 issues.

On my home turf of Thyroid UK, I often recommend people hop over here and read or discuss their possible B12 issues. From time to time, I also mention Thyroid UK to posters here. This has made me realise how rarely the medical establishment ever links the two. Yet this is not because there is no evidence, nor that the link is dismissed, but that the link does not reach those who need to know in their professional roles.

Complete achlorhydria occurs in more than half of myxedematous patients. As many as 25 percent of patients with myxedema, like those with Hashimoto’s thyroiditis, have circulating antibodies directed against the gastric parietal cells. This finding explains, at least in part, the frequency of achlorhydria and impaired absorption of vitamin B12. It is reported that up to 14 percent of patients with idiopathic myxedema have coincident pernicious anemia.

In case anyone who has Graves is hoping to escape:

It is possible that thyrotoxicosis may increase the need for vitamin B12, as shown experimentally, and perhaps for folic acid. Also, there is an increased incidence of antigastric antibodies and mild pernicious anemia in patients with Graves’ disease.

These are not quoted from a renegade, "alternative" source - but a very conventional site which has been written by some of the more respected thyroid experts.


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Mainstream medicine doesn't join the dots.

One huge aspect of their lack of dot joining is that they a) clearly don't understand b12 deficiency, and b) have never even heard of low stomach acid.

I'm tellin' yer - modern medicine is in a right mess.

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Thanks Rod,

There are more increased risk associated conditions with PA/ B12 def, expect the same will apply for thyroid conditions;


Associated diseases[2]

People with pernicious anaemia are at increased risk of developing gastric cancer, and there is an association with other autoimmune diseases (including primary myxoedema, thyrotoxicosis, Hashimoto's disease, Addison's disease, and vitiligo).


•Primary hypothyroidism

•Hashimoto's disease

•Addison's disease


•Diabetes mellitus

Kind regards,


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Okay, so what about hyperthyroidism?

I'm playing Devil's Advocate...


I'd just noticed your post on the thyroid site and saved it. Huge thanks for this Rod. With four member of our family now with Hashimoto's and B12 deficiency - it all makes so much sense!

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My personal belief is that even mild hypothyroidism, of any origin, is likely to cause some degree of hypochlorhydria. After all, producing stomach acid is a high-energy process and the lowered metabolism which results in so many other things (e.g. lowered thermogenesis, slowed gut transit) seems very likely to affect this as well.

It might also help to explain that so many people have low B12 when they first get a diagnosis. And that a good number seem to to manage on oral supplements, especially if they have also been diagnosed and are being treated for the thyroid issues. (Lots of those eventually diagnosed hypothyroid realise with hindsight that their issues have been going on for years. Certainly long enough for any store of B12 to be severely depleted.)

What impact low acid on entereohepatic recirculation... ?



But we've been through this theory before. If it was correct then the people on thyroid meds would resolve both stomach acid issues and b12 issues without needing further treatment.

That's all you have to do to prove that particular theory. Give thyroid meds, test stomach acid and test B12.

Another issue of course, is that although on this site thyroid gets lots of attention, on other sites many other illnesses are linked in the same way.

Again on the stomach acid issue and hypothyroidism - low stomach acid means lack of nutrients. So those hypo people should be suffering the symptoms of, to one degree or another, malnutrition.

There are also other things that slow gut transit - well outside of the remit of the thyroid.

I think we run the danger, and particularly on this site, of mixing cause and effect. And I also think that we rarely step outside of the box to look at what else is happening.

I'm not saying there aren't links, but as I've stated before because the thyroid is a balancing mechanism my theory is that it is not the cause of any problems but as a result of. Which I also think the B12 is.

What I am pleased about in the link, is that doctors are starting to draw the analogies.

What scares me, is that people who don't need thyroid meds, will be encouraged to take them. Because that can result in harm. Trying to regulate the thyroid with medications when the underlying cause has not been established (so let's say in this case the stomach acid is the cause of the tyroid irregularity rather than an effect of) just results in the thyroid trying to constantly readjust to problems not only in the body but also to the meds.

Mind you, I don't think the pharmaceutical companies would mind if everybody with B12 deficiency was given thyroid meds. Plus, of course, if the theory was wrong then the B12 damage would continue and you'd have a lot of people with permanent nerve damage.


For myself, I think I did go through a patch of lower acidity, low-ish B12, and recovery with adequate thyroid hormone. But I got treated relatively quickly and without going through severe hypothyroidism or very low B12.

I suspect I am not alone but I am also convinced that others have a much more complicated and tougher journey.

Most certainly I didn't mean to claim that this is the only thing going on or that any of it is that simple. The idea that low B12 in and of itself can cause thyroid issues has been going around for quite a long time and it seems interesting and plausible.

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Re. Give thyroid meds - it's not that simple ! The problem with thyroid disease, like B12 def., is that it's also not understood by the medical establishment and our family have had to struggle to, first get a diagnosis, and then optimal treatment. As Rod has indicated, many people have the same problem and, over time, low thyroid affects every cell and organ in the body, so it is not surprising that the stomach is affected. My heart (leaky valves & high BP), liver (high cholesterol), gall bladder, stomach (gastritis, H. Pylori, IBS) and brain (confusion, fogginess, paranoia) were all affected. Most of these problems cleared up over time with optimal thyroxine. The last link in the return to full health was B12 supplementation and avoiding gluten.

So, doesn't it all start in the gut - said to be the origin of the immune system, the other brain, and the seat of our emotions (trauma) ? A huge percentage of thyroid disease is Hashimoto's autoimmune.

I also believe that our family's autoimmune problems originate through maternal DNA - my mother had rickets as a child and, I now realise, undiagnosed B12 deficiency. She died early of breast cancer.


There are links to b12, thyroid, IBS, chronic fatigue, MS, ME, Fibromyalgia, Motor neurone, Parkinson's, Cushings, Adrenal function, Vit d3 deficiency, iron deficiency, auto-immune conditions (cause or effect, no one can decide), cholesterol, acholorhydria, heart disease, cancer - and these are just a few.

Now, when it comes to thyroid, I put forward a perfectly reasoned response as to why the thyroid is not the underlying cause of B12 deficiency or anything else (apart from problems arising from thyroid dysfunction) and that was, if everyone had thyroid meds then when their stomach acid was replete they should not have any remaining b12 deficiency.

Helvella's response was that he 'thought' he had low stomach and it was restored with thyroid meds. That's not any kind of response. Particularly from someone who never got very low b12 or severe hypothyroidism - I don't know what your levels were.

So, I ask again, why are people on thyroid meds, still B12 deficient?

And a point to make - I never, ever said B12 deficiency directly causes any kind of problem with the thyroid - other than the thyroid needs to readjust if there is a chemical imbalance within the body. Which is what its job is.


Perhaps I didn't put it very well but I'm trying to say that, as most people aren't given enough thyroxine unless they fight for it, they'll inevitably have ongoing problems with digestion & low stomach acid, be treated with PPIs, etc., with beta blockers for heart, and statins for high cholesterol, all the while getting older - all of this could eventually lead to B12 deficiency.

I'm sure you're right in that it's not just one deficiency though - our soil is now deficient in selenium etc. - but, when I think of Dr Amy Myer's (functional medicine), whose thyroid was removed, and Dr Terry Wahls, recovered from severe MS and now recommending her paleo diet, is it a coincidence that both were vegetarians but now eat meat ?

Like you, I'm trying to work it out

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An interesting link re. PPIs suppressing acid, B vitamins and thyroid


Thanks. I know that PPIs suppress acid...


Actually, that was very terse of me and I'm sorry.

Bottom line here - I'm a ghostwriter, for clinicians.

Getting some consistency on this forum and in the way we approach B12 deficiency and the damage it causes would help me point people in the direction of it and get us some publicity.

... and it's turned into the thyroid centre of the world and nobody seems to give a .... about neurological damage - and you can't direct people to a forum where they are going to get their physical symptoms trivialised.

It's like pulling teeth!

(It's a long time since I've heard molybdenum mentioned - I'd nearly forgotten about that)

(I'm not having a go at you, P)


Of course I know you know about PPIs P !!

The link isn't just about that - e.g. Connection with higher incidence of pneumonia - always more to learn.

I've also seen the terrible effect of neuro damage first hand......


I'm going to follow some of the research through in that article and see how solid it is. I've got some of them - I had read the pneumonia one - and the neuro damage link to you might be interesting...


... and if it is correct then it sorts of breaks up the thryoid causes low stomach acid argument.

So maybe we will start seeing a little more biochemistry enter the arena tied in with a bit of common sense.


In fact I'm just going over this - if you try and test the hypothosis simply by what is actually happening.

People on thyroid medications should not have b12 deficiency because the reregulation of stomach acid should have occurred by the introduction of the thyroid meds.

That is basically what you are saying?

What I'm not saying is that B12 deficiency causes low stomach acid - I'm saying it's a result of. And I think exactly the same about the thyroid ... which is why many people find it hard to keep their thyroid regulated even after getting treatment.


Hi All, just dropping in to add my own experience on this. I'd been treated for underactive thyroid for several years (Levothyroxine only), my low B12 was only picked up a year ago, and now Fibromyalgia has been added to the mix! When you look on the Thyroid website these two are shown quite clearly as "related conditions"! I feel GP's should be aware, and at the very least monitoring patients when they have blood tests. I'd become so unwell, I was convinced I must be dying. Any infection knocked me for six, and I took to my bed. Just getting across to the bathroom seemed to require more energy than I could summon. My husband drove me to the doctor and came in with me, I was unsteady on my feet, and found it almost impossible to concentrate on what was being said, or reply coherently to questions. Thankfully the GP did test my blood for B12 after that visit, and I have improved. I wouldn't say I'm well, but compared to then I am much better, and able to do things.

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Oh there is definitely a link - but the disagreement is related to the fact that Helvella believes that problems with the thyroid are a cause of low stomach acid which results in B12 deficiency.

I don't think that does happen and neither do I believe the processes are linear. It is more like a firework effect. We are oversimplifying the human metabolism by trying to find strictly linear effects.

My point of the debate would be that someone like yourself, once they started on thyroid meds, would not suffer from a B12 deficiency - if Helvellas theory held water.

The links between thyroid and B12 are evident. But there are also dozens of other illnesses linked. You mention fibromyalgia. Well, what is that? A syndrome, a collection of symptoms. And it will continue to be an unknown until doctors start understanding what B12 deficiency really is.

I do find it amusing that many people will say things like:

I have ME

I have fibromyalgia

I have MS

I have an auto immune condition

I have PA

If you ask the what it is they don't really know.

Then they will throw into the mix

...and I have b12 deficiency.

They think they know what that is. They think that is a blood condition that can cause some physical symptoms which are put right when blood levels are normalised.

It isn't.

With both B12 and thyroid, when they go wrong other things go wrong. Yet other things are causing the thyroid and B12 to go wrong. It's like a little detective story trying to track it all back.

I like to think of myself as a cross between Columbo and Mo Mowlam. This thought cheers me!


I love that vision, tell me do you wear the raincoat? Thanks for explaining, I'm a relative newbie to all this, but finding the help and advice on here invaluable. MariLiz


It's like a Parker - so it's close.

Bouncing around what happens to all of us is how we improve things - and many have different experiences.

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I have Hypopituitarism, diagnosed after a long fight with the Doctors , part of it is secondary hypothyroidism, last year again after battling with Doctors I was diagnosed with low B12 ( 104 ) , had the replacement shots ( 6 ) but still no improvement, last month I traveled to Thiland for more tests , after telling the Doctors my symptoms of tremors in my hands and feet , I was given a test for B6 , this come back well under the recommended level and I was given replacement B6 in tablet form , when I returned to the UK I asked my GP regards any help with the B6 , the reply was the NHS

Only replace B12 .

Seemed to be a pointless exercise like a lot of other things , and they wonder why they can't find an answer for CFS/ME - Fibromyalgia, yes I have that as well .

Eddie .


Thankfully the B vitamins can be obtained for moderate prices. But if you don't know that is what you need, it doesn't matter if they give it away at every street corner...

I agree B6 is an important issue but some people cannot tolerate high doses, and there is much controversy about even the doses that quite a number of supplements contain.


I agree with you , but why is it exempted that constipation , IBS is a part of hypothyroidism , B vitamins are low for a reason .

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I find this subject fascinating. I believe these are all autoimmune related. I have hypothyroidism, gluten Intolerance and low b12. I think this starts out as a food intolerance, my body attacking the Gluten proteins in wheat, barley and Rye. I have read in many articles that the thyroid gland is seen as similar by the body and your immune system attacks your thyroid at the same time The damage caused to the gut by the long gluten Intolerance prevents also b12 as well as other nutrients being absorbed. I'm no expert but that's my view on things.

After going to the docs for years i found I had gluten Intolerance by paying a fortune to see a nutritionist, but it's was worth it. My Doc treats my thyroid and b12 as totally separate issues and is not convinced by my gluten Intolerance, I know from my personal experience he is so wrong.

End result, I'm totally gluten free, now eat Paleo, 125mcg thyroxine and 3 monthly injections of B12, though I'm convinced I need the B12 much more frequently.

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