Folic acid mask b12 deficiency?

[Roo32]

When it is said that folic acid can mask the presence of b12 deficiency, can anyone tell me how is it this would occur? Would false b12 levels return in blood tests, or would the patient be less symptomatic temporarily whilst damage continues to occur unseen?

[fbirder]

Supplementing with folate can mask one symptom of a B12 deficiency - macrocytic anaemia. It cannot affect the amounts of B12 in the blood, not can it affect any assay for B12. I'll try to explain, but it's not simple.

Macrocytic anaemia can be caused by either a B12 deficiency or a folate deficiency. This happens because the body cannot produce enough of the chemical Thymidine. This is one of the four bases that make DNA (C, G, A, and T). It is made from the chemical Uridine in a reaction that requires methylenetetrahydrofolate (MeTHF). Uridine is one of the four bases that make RNA (C, G, A, and U).

If there isn't enough Thymidine then the body cannot make DNA, but it can make RNA (because it has plenty of U, but no T). RNA is required for the cells to function and grow, DNA is required for the cells to divide.

A deficiency of MeTHF means that the progenitors of red blood cells cannot convert U to T properly. So they can make RNA but not enough DNA. They can grow, but they cannot divide as often as they should. That results in fewer, but larger red blood cells - macrocytosis,

That's how a folate deficiency can cause macrocytic anaemia. But what about B12?

MeTHF is part of the folate cycle. It is converted to methyltetrahydrofolate (MTHF) which is converted to tetrahydrofolate (THF) which is then converted to MeTHF. But the conversion of MTHF to THF requires B12. Without enough B12 this conversion doesn't happen and most of the folate ends up stuck as MTHF. This is called the Folate Trap.

The Folate Trap causes normal levels of total folate (which is what is measured in blood tests) but it's nearly all MTHF and very little MeTHF. That means there's not enough MeTHF to make DNA and you have macrocytic anaemia.

If you supplement with folic acid then it enters the folate cycle as THF, which can then be converted to MeTHF which can then help convert U to T. There is no macrocytic anaemia.

But the B12 deficiency is still there. So lots of the other problems caused by low B12 are still present.

This is only a problem if you have an idiot doctor who believes that macrocytic anaemia is a necessary sign of a B12 deficiency and that, if absent, it means you cannot be deficient in B12.

Here's a document that explain the folate trap and folate cycle - b12science.com/B12Science/D...

[helvella in reply to fbirder]

From your excellent description, I am left suspecting there will be other specific issues that occur in cases of B12 deficiency but folate repletion?

For example, healing? Hair?

[Ritchie1268 in reply to fbirder]

Great explanation fbirder.

If only I had known all this about Macrocytic Anemia before I started B12 injections. I could've robbed a bank & lived a life of luxury without ever leaving any DNA as proof 😁

[Sleepybunny]

Hi,

B12 deficiency and folate deficiency can lead to enlarged red blood cells (macrocytosis).

If a person with macrocytosis due to both B12 and folate deficiency has only folate treatment then their red blood cells may appear to go back to normal size on Full Blood Count tests but the neurological effects of B12 deficiency can continue.

Link below mentions the importance of treating any co-existing b12 deficiency if folate treatment is given. See Management section.

Folate Deficiency

patient.info/doctor/folate-...

Macrocytosis

patient.info/doctor/macrocy...

Full Blood Count and Blood Film

labtestsonline.org.uk/tests...

patient.info/doctor/periphe...

Iron deficiency can mask the effects of B12 deficiency and folate deficiency on red blood cells.

Iron deficiency can lead to smaller red blood cells (microcytosis).

B12 and/or folate deficiency can lead to enlarged red blood cells (macrocytosis).

Iron Studies

labtestsonline.org.uk/tests...

I think the issue of masking is mentioned in this UK document.

BSH Cobalamin and Folate Guidelines

b-s-h.org.uk/guidelines/gui...

I wrote a very detailed reply on another forum thread with links to lots of B12 info eg B12 books, B12 websites, UK B12 documents/articles which you may find helpful. See link below.

healthunlocked.com/pasoc/po...

I am not medically trained.

[palmier]

It becomes a problem when doctors won't consider b12 unless they first find macrocytosis. Like in these NICE guidelines for chronic fatigue syndrome:

nice.org.uk/donotdo/tests-f...

"Tests for vitamin B12 deficiency should not be carried out unless a full blood count and mean cell volume show a macrocytosis."

[Sleepybunny in reply to palmier]

Hi,

I agree with you palmier .

I think BSH Cobalamin and Folate Guidelines mentions that many people with B12 deficiency do not have macrocytosis.

I never had clear signs of macrocytosis although I think MCH result was raised on Full Blood Count a couple of times but had many (over 40) typical symptoms of B12 deficiency.

PAS are trying to put pressure on NICE to produce guidelines for PA.

pernicious-anaemia-society....

NICE guidelines for ME/CFS are currently being reviewed. Can take years to produce new NICE guidelines though.

PAS have some input into review of NICE ME/CFS guidelines .

martynhooper.com/2018/02/10...

[Hidden in reply to palmier]

My GP told me I couldn't have a B12 issue because my red cells weren't enlarged. I was supplementing with folate and oral B12. I gave her lots of printed information sourced from here but she dismissed it all.

[SunnyWorld in reply to Hidden]

My doctor said the same years ago, I couldn't possibly have pernicious Anaemia as I didn't have macrocytosis. I recently tested positive after IF test.

[FlipperTD in reply to palmier]

This guideline is clearly influenced by imbeciles who assume they know everything.

Thalassaemia Minor syndromes are associated with a microcytic picture (typically MCV around 65fl) which can't be rectified; it's 'normal' for these patients. (To the ignorant, this can be confused with Iron Deficiency.)

Thalassaemia Minor syndromes have a significant incidence in some sections of the population. The Thalassaemia Minor patient with a megaloblastic bone marrow due to B12 or folate deficiency will have bigger red cells, but almost certainly not 'macrocytic' in the usual sense. They could however be expected to have hypersegmented neutrophils.

These symptomatic patients could be getting ignored if these guidelines are followed.

[Roo32]

Thank you all very much. I have a much better understanding of this now thanks to all your very clear guidance 🙏