Pernicious Anaemia Society
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MTHFR / Methylation Pathways Testing & B12 Query

Hi All

Firstly thanks again to everyone who kindly took the time to respond with help and advice to my first post here last week.

In summary for people who haven't read that post or thread: I was diagnosed with hashimotos hypothroid almost 2 years ago, coeliac disease soon after. I have positive parietal cell antibodies and generally things seem to be pointing to B12 defiency/PA. Im 100% gluten free and taking levothyroxine but feeling more exhausted than ever. Have lost my job, am unable to go out for more than a couple of hours (and even then feeling awful) and I want my life back.

I have put together an action plan on the back of my reading, research, informal discussions with a nutritionist, a lab testing company and other knowledgeable people along with all the comments from the lovely people from here and thyroid forum last week.

Unfortunately part 1 of my plan has failed already! I contacted my endo to ask for his authorisation for B12 injections. I mentioned some of the things that forum member Polaris and others had mentioned that Docs should do even if tests show normal levels, if patient still exhibits symptoms. This was his response:

"I do believe that B12 levels can appear normal when someone is truly deficient. However it is difficult to sanction treatment or ask your GP to kindly administer this when the results look “okay” as they may not feel comfortable prescribing under those circumstance. Secondly I mentioned in the past methylation pathway defect tests – if these are abnormal then the type of B12 you require may be just as important – too much or the wrong type of B12 and/or both can cause more problems. Therefore suggest working through the problem with Nutritionist with results may be best solution."

Now I have mentioned these B12 injections to him previously also. So I do not wish to push the point with him as he has generally been quite helpful and empathetic. However I need to take some action, hence the plan I wrote at the weekend.

MTHFR testing is one of the points on my plan.

So my questions here are:

1) re the Endo's letter above - I did not realise there were different types of B12 that I could take! Could anyone shed any light on this? And re: "too much" B12 - I thought that the body just discharges what it doesn't need?

2) Methylation pathway testing. I looked into this a lot last week and have found a couple of companies that do genetic testing. I have found it gets very very complicated! One site I found though seemed simple enough "23andme". Has anyway any experience of using them? If so is it possible to just find out what is going on with my thyroid and any vitamin/mineral defiencies? i.e I want to find out what is wrong with me now so that I can work on fixing it, and not get a load of data telling me I might have heart disease in the future!

I hope those questions make sense, and would be grateful for any helpful advice. Thanks for reading.


16 Replies

If you look through posts in the last few weeks you should find several about methylation problems

Forms of B12 that are available are - in ascending order of getting closer to the fully methylated formats

cyanocobalamin (used in US)

hydroxocobalamin (used in UK)



Cyano is the most stable form.

You need to be a bit careful about which forms of B12 you use if you have an MTHFR mutation as methylcobalamin can be a disaster for at least one.

There is a theory that actually taking less methylated forms clogs up the system and stops the more methylated forms. One of the posts has a link to an explanation of this. Not sure that it really applies if MTHFR isn't a problem as I find using a range of forms of B12 quite beneficial.

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This link may be useful - seems to be quite a balanced introduction to MTHFR

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I found that interesting actually, thank you


Thanks Gambit, I'll have a search back through those posts.

It seems that's perhaps why my Endo is urging caution before I go down the B12 route, and suggesting I check MTHFR issues first.


Sorry, one last reply to your post! Are you saying that personally you take more than 1 B12 form? Thanks


currently using hydroxo (best for depression and anxiety), methyl (helps with tingling and numbness in my feet), and adenosyl (gives me more range of motion in my left foot and also helps with the tingling and numbness

However, these are my responses and others could be totally different.

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Thanks Gambit. I've ordered the genetic kit now, so hopefully I'll know soon re B12 (amongst other things)

I'm glad to hear that you're responding well to the different B12's


You have certainly been very proactive in approaching your problems Lee.

Seems that, as usual, the clinicians are all sitting on the fence, sticking to test based medicine only, and unwilling to recommend or follow guidelines when the fact is that you have all the indications of an absorption problem leading to neurological symptoms that are badly affecting your life and need to be treated as soon as possible.

It might be worth contacting the PAS re. MTHFR and how this would be affected.

I'm not sure whether the following is helpful or not, as Hydroxocobalamin is usually prescribed in the UK:

"Cyanocobalamin is the most stubborn form - that's because in this type the B12 is bound to a cyanide group which won't let B12 get free that easily. Yes, it does protect B12 from extreme conditions (such as high temperature, etc) but it doesn't let the body free up the B12 that's bound to it". "There's another reason why we shouldn't like this form of B12 - that's the fact that Cyanocobalamin is excreted by the kidneys as if it's some toxin bound to B12 (which is one of B12's functions). So, of course, none of us like getting our B12 flushed out whenever we eat it with the intent to replenish our stores".

"Since the body uses Methylcobalamin and adenosylcobalamin, these forms are the best when it comes to what form of B12 you should take.

The form Hydroxocobalamin can also be used by your body after it's converted to Methylcobalamin."

"The two forms that the body uses are the coenzymes adenosylcobalamin and Methylcobalamin. Most enzymes of the human body are proteins by nature. A coenzyme is any non protein substance that is absolutely necessary for certain enzymes to carry out their respective reactions".

Extracts from 'The B12 Deficiency Survival Handbook', by Dr Aqsa Ghazanfar .

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Thanks Polaris. I'm just fed up with waiting months between endo / gastero appointments and dose tweaks which don't seem to be getting me anywhere except feeling worse.

I want to get back to work and a life but from where I am now I just can't see it. So I have to try something new. I drew up that action plan. The big possible plunges are switching to natural dessicated thyroid and taking B12 injections. Both of which concern me so I want to be sure before I start. In the meantime I've sent off for test kits for various things including adrenals.

So next I need to get MTHFR issues checked, hence this post I guess.

Thats a good idea I may contact the PAS directly, thank you.

Thanks for those extracts re B12 types. Do you take a particular form, if you don't mind me asking?


I came to start researching B12 through various misdiagnoses within my family - four of us have autoimmune thyroid/B12def. My sister became seriously deficient with neurological damage and is now doing well on monthly injections plus daily supplementation of Jarrows Methyl. 5000 mcg. SL. (good reviews on Amazon for neurological symptoms). Sally Pacholok (Could it be B12?) recommends covering all bases.

I changed to Thyroid-S NDT four months ago with no problems, encouraged by other's experiences on the Thyroid UK site here, and find I now have more energy and motivation - if you do decide to try it, start gently and raise dose slowly. I also supplement B12 with the Jarrows 5000 as I'd, luckily, not reached the stage of having neurological symptoms.

Hope you start to feel better soon Lee.


Well today I've ordered the genetic testing kit, and the kit arrived today for the other tests I ordered. So I'll get the samples done and sent back, go for the thyroid blood test next week, then sit tight, wait for all the results. Then it'll be time to decipher them and then decide exactly what to to next re meds, B12 and supplements.

Thanks for your kind words. I'm glad you and your family are feeling the benefits of the changes you have made.

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This is a recent article about the MTHFR tests which I thought was interesting:

I have done the 23andme test. It is not possible to find out just some information - so if you are worried about what you might find out, it might not be for you. There isn't any information about pernicious anaemia at all at the moment on the 23andme site and nothing about vitamin deficiencies. And it only gives you probabilities of you developing diseases in the future rather than any information about your current health. You can feed your 23andme results into another site to get MTHFR information but I don't know how accurate/based on science it is. I think you can register on the site without ordering (at least you used to be able to) and have a look at an example of the information you would receive.


Thanks Laura. Yes that's what I though, it might be a list of "may haves/may gets" rather than actual facts.

Did you find it useful in helping your current health situation?

Thanks for the article. I've read quite a few articles like this pooh-poohing the MTHFR testing. I'm not that worried about what I might find out but I accept I'm desperate and it could lead me down the wrong path in terms of supplements and regimes.


I found it interesting - but I wouldn't say it helped at all - only that it pointed out that I have risks for some autoimmune diseases which I wasn't really aware of. I like having access to (some of) my genome so that when I'm reading about things I can look up my own results and compare them - but even if you have a mutation it only points to an increased risk rather than anything definite.


Hi Laura

Well the kits arrived today for the tests I ordered this week, and I've also taken the plunge today and ordered the genetic testing kit. Blood test next week for thyroid. So Hopefully in a couple of weeks I'll have loads of results and data to sift through then make decisions on what steps to take.

Thanks again for all your comments and helpfulness

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Great. Really hope they help you get to the bottom of what is going on.


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