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Pernicious Anaemia Society
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Folic Acid causing damage until B12 levels restored?

A member has commented on a thread here that the above can happen until you're at least 80% topped up, and to NOT take Folic until that time.

This really scared me as a lot of Newbies to this whole PA life might be causing themselves further damage.

Can ANYONE verify this and perhaps provide a link or two for others to read?

I did ask the member to expand and provide some info source but have not had a reply as yet, I know I may appear impatient, but, look...........EVERY day is important to me right now, and the thought of damaging instead of healing myself is freaking me out lol

5 Replies

I can't speak to whatever research the other poster was talking about.

As I understand it, the issue with taking folic acid before treating b12 deficiency is that it can mask macrocytic anemia (enlarged red blood cells). A deficiency in either B12 or folic acid can result in enlarged red blood cells. If the cause of the anemia is B12 deficiency but the patient is treated with folic acid instead, the blood cells will return to normal size, but neurological damage due to the B12 deficiency will continue until the B12 deficiency is addressed. If the doctor is going strictly by the numbers on a lab report, they will mistakenly think they have correctly treated the problem. That is why they are advised to rule out a B12 deficiency before going ahead with a folic acid treatment.

I'm not up on the latest research, so I would not be aware if there is something new that has come out regarding folic acid. The body does need iron, B12, and folic acid all in good supply in order to create red blood cells, so if the patient is low in both B12 and folic acid (as is often the case), it is ok to take both vitamins at the same time in order to restore levels in the body.


Right now that makes sense, thank you Galixie !!! Perhaps a slight language barrier then; so just to clarify it may be that that member was trying to say something along the lines of ....'misunderstood blood results may cause the symptoms to be treated with increased folic acid to the detriment of B12 which can lead to further neuropathy' I guess.

Phew, putting kittens back in basket lol


There is a lot of info on folic acid in the film about Sally Pacholok, e,g, :

" individuals with low B12 and high folate levels had more neuro cognitive deficits than those patients with low B12 without high folate levels." Ralph Green, MD, PhD



"High levels of folate are normally okay as long as your vitamin B12 level is also normal. Cells need vitamin B12 to use folic acid and when vitamin B12 levels are too low, folic acid cannot be used and builds up in the blood." :



Sally Pacholok and various specialists also talk about folic acid as well as B12 deficiency in this video :

Haemotologist's quote:

"If you treat someone with B 12 def. with folic acid, you can either precipitate neurological abnormalities or, if the patient already has neurological abnormalities, you can make them worse. So folic acid should never be given empirically unless the B12 status is normal."


BMJ Research Document:

cmim.org/pdf2014/funcion.ph... :

"If there is concomitant B12 and folic acid deficiency, then B12 must be started first to avoid precipitating sub acute degeneration of the spinal cord.

"In patients with isolated vitamin B12 deficiency and anaemia, additional folic acid is recommended until vitamin B12 is replete to prevent subsequent folate deficiency after replenishment of B12 stores.


There appears to be evidence that folic acid supplementation does not suit everyone, including in the latest book on vitamin B12 and chronic illness. Personally, I don't take a supplement, although it's usually added to B complex. I prefer to eat plenty of folate rich foods.




the bigger issue is that supplementing with high dose folate when you are B12 deficient brings a small risk of precipitating spinal chord damage. The effect has been demonstrated in fruit bats and there are a few reported cases in the literature surrounding humans.

I'm not sure where the 80% comes from or what it could possibly mean as a B12 shot will put your B12 levels way over the normal range. Generally it's a question of not supplementing folate until after you have had your fist B12 shot - 24-48 hours

If you are UK based then this is detailed in the BCSH guidelines which you can access here (but may not be accessible if you are outside the UK)


the risk with masking macrocytosis mainly works because of the large number of medics that think B12 deficiency is all about and caused by macrocytic anaemia - in which your red blood cells are larger and rounder than normal - it isn't - that is a symptom and one that isn't present in 25% of people first presenting with B12 deficiency.


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