Hi all, My case seems to be a little murky. In 2018 I found out that I had very low B12. I was a vegetarian at that time and for the last 2 years have been vegan. Back in 2018, I began injections which brought my level very high very quickly. At that time I also took my first intrinsic factor test. It was positive, but it was shortly after my first injection which can result in a false positive. After several months of injections, I began taking a sublingual 1,000 mcg per day, and have regularly tested MMA, folate, homocysteine, Etc, all within range each time. I have also had at least 5 negative intrinsic factor results since... until now. Incidentally, I do not have any discernable symptoms. Just this past week my intrinsic factor result was slightly elevated. That is why I decided to look into an active B12 test, which unfortunately isn't available in the US. The other complicating factor was that back in 2018, when this all started, I had gastritis. The related similarity to that time was me recently recovering from another stomach ailment that took months to deal with (strong antibiotic wiping out gut flora). I was looking for a good doctor to be able to ask if perhaps both stomach ailments may have had something to do with affecting the intrinsic factor test results. Present B12 level is at 771 (200-1200 test range). I was hoping to not have to start injecting again unless necessary. I have not injected since 2018. My levels have remained in the 600 to 900 range since then on a 1,000 mcg sublingual daily. I've been monitoring with bloodwork every 6 months for the past couple of years, and these latest results were the first time I had a slightly elevated IF number (1.2 AU/ml, range 0 - 1
1) since 2018 (has been 1.0 all along). My iron (94, 38-169 range) and ferritin (46, 30-400 range) numbers also decreased a bit (vegan diet may play role). TIBC is 385 (250-450 range) and iron saturation is 24, 15-55 range. Still wondering if winter stomach issues after killer antibiotic messed up my system so much as to interfere with absorption. MMA (107, range 0 -378), folate (13.6 ng/ml), and homocysteine (10.5, 0-17.2 range) numbers are good. MCV is normal. I guess I'll just keep monitoring in another 6 months? That's why I was hoping to find a doctor with good knowledge about b12 (likely a fantasy) to knock this around with and/ or was looking into a functional (active) b12 test in the USA (another fantasy). Thoughts, suggestions? Thanks!
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Greeneyecolor
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b) SIBO (bacterial overgrowth in the small intestine) is a known cause of B12 deficiency. There is a strong cross over with PA (as an auto-immune gastritis - associated with IF Antibodies) and that seems to go both ways - people with SIBO developing PA and those with PA developing SIBO.
c) interpreting serum B12 levels is difficult - in someone who hasn't had injections they tend to be pretty constant at a point in an enormous range that is right for them. In someone who has had injections they will fall until they get to that point (if no absorption problem) or just continue to fall if they do have an absorption problem so gets even more difficult to monitor after injections have started.
Given the length of time since your last injection it sounds as if somewhere around 600-900 is the right place for you (given that the test is only accurate to 20% anyway).
Unless you are developing symptoms of B12 deficiency - think from your post that you are saying that you don't you probably don't have an absorption problem but you are at risk from a dietary deficiency ... and potentially from further episodes of gastritis, so just continue with the oral supplements (though you might well be able to get away with a much lower dose if you don't have an absorption problem.
Please note that dietary deficiency is, strictly speaking, off topic for this forum - mainly because a dietary deficiency can be permanently resolved by using supplements but a permanent absorption problem like PA can't.
Thanks for your reply. I had been diagnosed with PA initially in 2018 after first IF test was positive. That was why I was seeking an active B12 test. Cannot find a lab that does holo-t here in the US.
try a different test supplier - it may be that they are still using old kit and not prepared to change - generally people seem to change to kit testing active B12 but all of the kit is expensive.
Scientist, not medic. I suspect I'll get folks throwing stones after I've finished this, but here goes:
Your IF Antibody test is negative. You've done several and apart from the first one [probably false positive due to a load of free B12 in your system] they others have all been negative. As I've said before, attempting to put a number on things only confuses. A range of 0-1 [of what?] and a result of 1.2? That looks like 'noise' in the system. My experience of IFAb testing is that once you get a genuine positive, further testing in future just gives stronger results as the 'antibody titre' rises over time. If you're able to maintain and increase your B12 level on oral supplements then you're absorbing it, pure and simple.
The iron-associated results look fine, and what you've told us about your blood [MCV normal] then I doubt there's much to worry about. Keep on doing what you're doing, but don't obsess about your results. I would suggest that it's not necessary to go hunting for further tests such as HoloTC either. Your total B12 is healthy, your MCV is normal. It's a case of 'Move on. Nothing to see here!'
"In 2018 I found out that I had very low B12. I was a vegetarian at that time... "
Have you tried to estimate how much b12 you ate back then? A vegetarian diet doesn't have to be too low in b12. Milk for example is a very good source of b12. It varies a bit, but 300 to 400 ml of milk is often enough to cover the recommended daily intake of 2.4 mcg. And vegan milk is often fortified with b12.
If you had a very low B12 despite getting the daily requirement you could definitely have (or have had) an absorption problem for b12.
The mg‐tablets (1000 mcg) you take contains more than 400 daily requirements each, which means over a years need in each tablet. So if you need these strong tablets to maintain normal serum values you may still have an absorption problem.
I dont think PA should be ruled out, because a negative IF test doesn't really prove anything, and you've actually had two positive tests. Other possible causes for an absorption problem are celiac disease or Crohn's.
Even if you have PA you may be one of the lucky ones who manage on strong tablets (mg doses). It doesn't work for everyone.
Small clarification on the 1000mcg dosage - If you only took the 1000mcg B12 twice a week, the 1000mcg tablets would be adequate to cover only a week's B12 requirement. This is because a week's minimum B12 requirement (2.5mcg x 7) is 17.5mcg.
Amount Absorbed:
Intrinsic Factor: 1.5mcg x 2 = ~ 3mcg
Passive Absorption(1% of the dose) = 10mcg x 2 = ~ 20mcg
Total Amount Absorbed for the week : ~ 23mcg
Despite the large amount of B12 in the tablet, the tablet would NOT cover your B12 requirement for a year. In fact it wouldnt cover 2 weeks. The regularity of B12 intake and way the absorption works is of huge importance to understanding how much and how often, is enough. More regular doses can be much lower ; less frequent doses need to be a lot higher to get enough since you are then mostly reliant on passive absorption which is massively inefficient (in fact its been described as an "accident of physiology").
But since you're taking B12 every day, if you do not have absorption issues, a single dose of 100mcg is usually sufficient:
Intrinsic Factor : 1.5mcg
Passive Absorption (1% of the dose): 1mcg
Total Absorbed : 2.5mcg
Or up to 500mcg daily if you have low stomach acid, or wish to be extra cautious. If more than 500mcg is needed daily long-term that would seem suggestive of a possible absorption issue.
2.4 mcg is the recommended intake (as opposed to uptake). About 1 mcg of uptake is thought to be enough for a healthy, not deficient person to maintain their b12 levels.
If a person isn't keeping their levels up on either a standard multivitamin containing 2.4 mcg, or corresponding from food then I'd say there is an absorption problem.
Just because a person is a vegetarian or vegan that need not be the cause for their b12 deficiency. Dairy (as part of a vegetarian diet) is a good b12 source, and some vegan products are fortified.
Just go to the fridge and check the milk package. In UK it typically says 0.9 mcg per 100 ml. (In Sweden, for some reason, it's only 0.6 mcg per 100 ml.) Vegan milk is often fortified with around, I think, 0.4 mcg per 100 ml. Many breakfast cereals are fortified, often including b12. And many vegans take a supplement suitable for vegans. There's no need to be b12 deficient just because you don't eat meat.
I agree 100% that there is no need to be B12 deficient just because you don't eat meat (or any other animal products). I am vegan. I take a supplement formulated for vegans that has all the necessary nutrients which are difficult or impossible to get for vegans.
But your statement that a standard multivitamin containing 2.4mcg of B12 should be adequate for vegans is not consistent with the advice of vegan registered dieticians nor of how the absorption of B12 is understood to happen. If such a supplement was the only source of B12 in the diet, the total B12 absorbed could be under 2mcg. This would not meet the RDA. Could you survive on this intake? Possibly. Is it worth risking such an intake considering the consequences of deficiency? Absolutely not.
The recommendations at veganhealth.org are formulated by registered dieticians and their recommendation for a single daily dose of B12 that satisfies the European Food Safety Authority's adequate intake is 100mcg.
It is possible to take much less and still meet intake requirements but only if B12 is consumed at 2 or more intervals throughout the day separated by some 3-4 hours to allow for intrinsic factor availability.
The RDA was formulated with an expectation that small amounts of B12 would be eaten at more than one meal, which is typical in an omnivorous diet. With vegans, unless they are eating fortified foods, this is not necessarily the case - the single supplement might be their only B12 source that day. It is possible to meet the B12 RDA solely with fortified foods, and although its possible, I dont think this is the recommended (or safest) way for vegans to get their B12.
Many vegans are health conscious and may buy their plant milks at health stores - I have found that the plant milks in such stores (at least in this country) are not fortified with B12, or Calcium, or Iodine, all of which are important with plant milks.
Many health conscious vegans avoid typical super market cereals which are fortified, to avoid added sugars, and may instead buy various muesli or granolas, or make their own, which often are not fortified in my experience.
1000mcg is not enough B12 to cover your intake for a year, since only 11-13 mcg or so will actually be absorbed - so it only enough for just over half a week if that was your only B12 source.
My own B12 deficiency was the result of exactly this kind of misunderstanding about intake regularity and the RDA. I was taking 100 times the RDA - 250mcg in a single dose every week and I was advised by clueless doctors, when I developed symptoms, that this was actually too much and I should take this dose once a month - which seems ok if you do the (incorrect) simple math but not if you understand the actual absorption mechanisms.
If you look at the table on veganhealth.org you will see that a minimum single weekly dose needs to be around 2000mcg (1250-2500mcg). This is because of passive absorption in that case being the primary mechanism. It is not possible to estimate an adequate intake without understanding the absorption mechanisms and the regularity of intake. The RDA must be understood in that context.
Ok, you're right. I didn't mean to imply that a single1000 mcg tablet would give anyone enough b12 to last a year, but I could have expressed myself clearer. My point was that if levels are kept normal by taking a daily1000 mcg tablet then maybe it's thanks to passive absorption and not IF mediated. So there could be an absorption problem, if normal doses near the RDA wouldn't be enough.
I think the RDA of 2.4 mcg is set with the awareness that only around 50 % is absorbed from moderate amounts, (provided functioning IF). The numbers I've seen is that 30 % to 70 % is absorbed, and that on average an intake of 2 mcg could be enough. 2.4 is set with some margin.
But better safe than sorry. B12 is safe and cheap and absorption can be affected by many factors so there's no reason to keep intake at minimum. A normal non-vegetarian diet often gives more than the RDA.
Sorry to hear about the bad advice you were given regarding how to take b12. Doctors need to be better educated about this. Many bottles with 1000 mcg tablets state that this corresponds to 40,000 % of RDA, without mentioning how little is actually absorbed.
When a doctor prescribed me 1000 mcg tablets for a low b12 I only took them for a short while because they seemed so horrendously strong, and my b12 was only borderline low, just under reference range. Took me many years to realise what a mistake this was.
Greeneyecolor A daily supplement of 500mcg is recommended for older adults even if they follow an omnivorous diet, due to risks of lower absorption associated with decreased stomach acid. But 1000mcg is (probably) more than you need if you don't have an absorption issue - although its still a safe dosage.
"Adults over 50 years of age should meet the Recommended Dietary Allowance by consuming vitamin B12 in the crystalline form, which does not require gastric acid or enzymes for initial digestion. A recent clinical trial suggests that an oral dose of 500 microg/d of crystalline vitamin B12 is needed to reverse biochemical signs of vitamin B12 deficiency in older adults. "
palmier you are correct though about 1mcg being the estimated requirement, but I just think its safer to estimate whats needed to hit the RDA, not the minimum estimated requirement, especially since some papers suggest the need for a higher requirement.
It is hard to comment on blood tests with out the context of symptoms but you do need to take a B12 supplement if vegan and dont worry if results go high as a result.
Having had MMA tests regularly, assuming within range (the one given, 107, comfortably mid-range) would rule out SIBO. Small intestine bacterial overgrowth rob you of vitamins (B12 being one), so would also give you symptoms indicative of that.
High or raised MMA would point towards renal problems (this as a cause could be ruled out by blood tests), B12 deficiency (pre-injection) and functional B12 deficiency ( post-injection, as MMA should return to within range certainly after loading injections) and SIBO (which can deplete B12 and fat-soluble vitamins (A,D,E,K). A SIBO test involves fasting, 3-4 hours of breath tests, results of which can be plotted by medical experts to determine likelihood of SIBO as cause. All of this can be done by the NHS if there is reason to believe that there is a problem with MMA.
In your case, this does not appear to be a problem. Tests have not shown any problems and you do not have any symptoms currently. If stomach issues recur, you might ask for a SIBO test, but doubt you would get one on the NHS unless MMA test showed abnormal results first.
Human beings are animals which evolved as omnivores. Eating strictly vegan is not normal for our species, and has a whole host of negative consequences, psychological as well as physical, as described in this medical journal article from 2/2023: ncbi.nlm.nih.gov/pmc/articl... As with most things in life, no diet is 100% perfect on all levels of consideration. In terms of protein sources, while I eat a small amount of chicken, I'm mostly a pescatarian, focusing on wild caught fish. I can appreciate the negatives associated with a heavily farm-raised meat based diet, but my suggestion is that you seriously reconsider radical veganism.
Thank you for your reply and advice. I do respectfully disagree though. There is so much counter evidence to the link you sent (including most of the sources the article cites, if you read through), but in the long run, to each his own. This is not the forum for such a discussion anyway, except as it pertains to B12, and to that extent hopefully my daily 1,000 mcg sublingual will continue to do its job. Again, thanks for your reply.
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It's expected to give you around 10 mcg as uptake, 
B12 blood results 
Tests while on injections
3yrs later and Active B12 Results
Post-treatment lab results -- interpretation help appreciated!
