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Are 50mcg tablets as effective as 1000mcg sublinguals?

Sarahlouise1980
Sarahlouise1980
25 Replies

Hello,

I’ve just popped over on recommendation from the thyroid group. I’m just wondering if the 50mcg cyanocobalamin tablets I have from the chemist would be as effective at raising my low b12 levels as the 1000mcg sublinguals with out the side effect of awful skin! I’ve been on the sublingual for three weeks and I’m covered in an itchy acne type rash.

Thank you!

Sarah xx

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pvanderaa

The tablets won’t work at all if you have an absorption issue in your gut. (i.e. a problem with IF or parietal cells.)

Subl absorb into the blood stream under the tongue.

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fbirder

They should be yes.

None of the B12 will be absorbed sublingually as the B12 molecule is too large to cross biological membranes unaided. It is only the swallowed dose that can be absorbed.

And only around 10 mcg of a sallowed dose can be absorbed.

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palmier
palmier
in reply to fbirder

I've heard that around 1 % of a sublingual is absorbed. What melts in the mouth will of course eventually be swallowed, so it gets a second chance to be absorbed in the gut. That must make it difficult to test exactly where the b12 is absorbed.

B12 is sensitive to stomach acid, so perhaps the point of sublinguals is to absorb some b12 before being attacked by the stomach acid? Haptocorrin (transcobalamin I) produced with saliva protects b12 from the acid in the stomach, but according to Wikipedia it's produced in response to ingestion of food. So what happens if you swallow a pill when you're not eating, which is sometimes recommended, do you get enough haptocorrin to protect the b12 from the stomach acid?

en.m.wikipedia.org/wiki/Hap...

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fbirder
fbirder
in reply to palmier

But people absorb B12 from oral supplements. Indeed, they absorb just as much from oral B12 as from sublingual B12.

If B12 could be absorbed sublingually then none of us would need injections. All we would need to do is use B12 suppositories.

If a molecule can pass across membranes then rectal administration is much better than sublingual. A sublingual dose is in contact with the membranes for a minute or two. A rectal dose is in contact with the membranes for several hours. That means much more of the drug will be absorbed. A 1000 mcg rectal dose of B12 should see at least 500 mcg being absorbed. It would mean one suppository a month, rather than an injection every two months.

Some people tried to patent B12 suppositories. Nothing was heard from them, presumably because they don’t work.

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palmier
palmier
in reply to fbirder

Well, I don't think b12 is absorbed across *any* mucous membrane. Not in the large intestine, for example, because it has to be quite impermeable. The membrane under the tongue, on the other hand, is supposed to be quite thin.

Injections give large doses in short time, so they are better at restoring levels quickly, and I suppose they also give better control over how much you get because absorption is guaranteed (though not all is retained).

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fbirder
fbirder
in reply to palmier

The membrane of the large intestine isn't thick. The membrane of the rectum is really good at absorbing drugs.

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deniseinmilden

I'm sorry Frank but that just isn't true.

While the transdermal route although technically clinically proven, I agree is questionable, the sublingual route is definitely, unequivocally effective in practice for at least methylcobalamin.

If science hasn't found out how or why yet, it is just because more work needs to be done on it.

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fbirder

No it is not at all proven.

Yes 1% of a sublingual dose of 1000 mcg of methylcobalamin is absorbed, but 1% of an oral dose of 1000 mcg is methylcobalamin is absorbed.

If methylcobalamin could be absorbed across the buccal membrane then you would expect the total absorption to the buccal+intestinal.

For a 1000 mcg oral dose intestinal absorption = 10 mcg (because buccal absorption is zero).

For a sublingual dose there is no reason to expect intestinal absorption to be any different (for the vast majority of the dose that is swallowed). So intestinal absorption = 10 mcg.

As buccal absorption + intestinal absorption = 10 mcg buccal absorption must be zero mcg.

Sublingual has been shown to be no more effective than oral. That doesn’t mean that sublingual absorption happens. Indeed, it means or almost certainly doesn’t happen.

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deniseinmilden

Thank you for your reply.

Great theory, as are 3 monthly B12 injections...

On the contrary I and a lot of other people get zero benefit from swallowing B12 tablets of any strength but do get a measurable effect from sticking them under our tongues and letting them very slowly dissolve.

Chewing them and quickly sucking them to rapidly dissolve them before swallowing doesn't work either so it's not particle size or lack of tablet breakdown that is the issue either.

At the moment I have had a bit of an improvement in my GI absorption but for a while almost nothing seemed to be absorbed once I swallowed it and I was amazed by what could be absorbed across the membranes in my mouth... thankfully!

Sublingual sprays are a life-line for some people when tablets just don't work.

Remember everyone is different and science is advancing daily!

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Gambit62
Gambit62Administrator
in reply to deniseinmilden

studies have shown that sublingual results in more absorption than oral but a) studies have been quite small scale b) the difference is between just below 1% and just over 1% so not really a practical difference.

ncbi.nlm.nih.gov/pmc/articl...

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deniseinmilden

Thank you!

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fbirder
fbirder
in reply to Gambit62

Sorry, but that paper just says exactly what I said, with numbers.

Sublingual B12 raised levels to 288 pmol/L

Oral B12 raised levels to 286 pmol/L

There was no significant difference in concentrations between the treatment groups.

Exactly what I said. Absorption from sublingual was the same as from oral.

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palmier
palmier
in reply to fbirder

Perhaps the serum value after 4 weeks isn't a perfect measure of what is actually absorbed? There were no other symptoms to consider, no high MCV, MMA or homocysteine and there is no mentioning of peripheral neuropathy or SCDSC, it was all about normalising the serum value, which worked.

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fbirder
fbirder
in reply to palmier

Give people oral B12 and serum levels go up because it has been absorbed.

Give them sublingual B12 and the serum levels go up by the exact same amount because the exact same amount has been absorbed. If more had been absorbed then serum levels would be higher.

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palmier
palmier
in reply to fbirder

I still don't think the serum value alone is a good measure of how much was absorbed, because it increased a lot after one week, and much less or not at all the following weeks. A serum value of +200 pg/ml corresponds to no more than +0.5 mcg in 2.5 L serum, and they must have absorbed >10 times that every day.

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palmier

If you don't have an absorption problem it might be even more efficient to buy 10 mcg tablets and spread them out through the day, because as fbirder pointed out there's a limit to how much can be absorbed each time.

Do you know why you are deficient? If it's because of diet or absorption problem?

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BadHare

My acne outbreak went away after a few months of injecting hydroxocobalamin. It’s worth sticking with the sublinguals to see if yours clears up rather than risk low B12.

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Gambit62
Gambit62Administrator

take the tablets that you have from the chemist.

As has been said a number of times now, they will be more efficient than large dose oral,unless you have an absorption problem.

If you do have an absorption problem they won't do anything so it will make it clear that you do have an absorption problem if you stick with them rather than going for large dose sublinguals which can make it difficult to see what is really going on.

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Sarahlouise1980

Thank you gambit62. Shall I start with one 50mcg tablet a day?

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Sarahlouise1980

If I stuck with the 1000mcg sublingual would the acne clear eventually?

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Gambit62
Gambit62Administrator
in reply to Sarahlouise1980

per response to PM - your serum B12 is significantly below bottom of normal range - unless you are a vegan this means you have an absorption problem.

A negative result on IFA does not rule out PA as the test is notoriously insensitive.

Your GP should be treating the B12 deficiency before putting you on high dose oral for the folate deficiency - this is what is stated in the NICE guidelines and also in the BCSH guidelines.

With an absorption problem 1000mcg sublingual isn't going to be very efficient at raising your B12 levels and you really need to be on injections.

The acne is probably temporary but there are never any guarantees - people are individuals and everyone does respond differently.

The most likely explanation for the acne is that it is a reaction because micro-organisms on your skin are reacting to the higher levels of B12 by releasing an irritant. speak to a pharmacist about a suitable skin wash. It is a reaction that usually calms down but I can't guarantee that.

cks.nice.org.uk/anaemia-b12...

NICE guidelines see section about testing B12 if folate deficient

onlinelibrary.wiley.com/doi...

BCSH guidelines - have a detailed discussion of the limitations of various tests involved in diagnosing B12 deficiency - including the high probability of false negatives with IFA.

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Budsa

Hi Sarahlouise1980,

When my doctor prescribed the 50mcg tablets for low B12 they were to be taken 3 times a day on an empty stomach. I took them upon waking, mid afternoon and before bed.

If you are only able to absorb B12 passively, and only 1% of ingested B12 is absorbed this way, then you would absorb around 1.5 mcg, which is close to the recommended daily dietary intake.

The above dosage is normally recommended for patients who are deficient owing to being vegan.

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Sarahlouise1980

Hi budsa,

I guess I’m confused. I tested negative for the intrinsic factor but I have low b12 & folate. Possibly because I’m hypothyroid. I’ve been taking the 1000mcg sublingual but have broken out in an acne type rash on my face and body. I’m just confused as to the best way forward as I know I obviously need to raise my b12 x

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Budsa

Hi Sarahlouise1980,

I don't think being hypothyroid can lower your B12 but it is very common to suffer from both hypothyroidism and PA. They are both autoimmune conditions. Only 40-60% of people with PA test positive for intrinsic factor antibodies.

If I were you I would stick with the 1000 mcg tablets for a period of a couple of months to boost my levels and then drop to the 3 x 50mcg afterwards.

If your B12 level is below the NICE threshold or you are suffering any neurological problems then you should probably be on IM injections.

Some people on other threads that have suffered from acne after B12 supplementation find that it clears up after a few months or even sooner.

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