Hi
I wrote yesterday asking about self medicating with b12 tablets and sub lingual spray. I have been assured by both my doctor and fellow bloggers on this site than one cannot overdose on b12 I was therefore surprised to read a warning on the NHS site under vitamins and minerals in relation to my vegetarian/vegan diet a that taking too much b12 can be harmful.
I find this statement at odds with everything else I have been told.
I wonder if anyone else has seen this advice?
Have you got a link to that, please?
Hi
I can't find a link code. It on the page entitled vitamins and minerals b vitamins and folic acid. It's at the bottom of the page. If you can't find it give me your email and I'll send it to you.
Is this it?
What does the Department of Health advise?
You should be able to get all the vitamin B12 you need by eating a varied and balanced diet. If you take vitamin B12 supplements, do not take too much, because this could be harmful.
Taking 2mg or less a day of vitamin B12 in supplements is unlikely to cause any harm.
nhsdirect.wales.nhs.uk/ency...
I'd point out that 2mg is already quite a high dose. Sure, some people take 5mg or more each day.
And if you follow the link from that page, I can't see any mention of "excess"...
nhsdirect.wales.nhs.uk/Ency...
That's the page - you think it's all right then?
I am perfectly happy taking up to 2mg a day (2000 micrograms). Never noticed event the slightest negative impact.
(I do not have PA - just think my B12 is sometimes a bit low.)
There is no evidence on any harmful effects from high dose supplementation - it admits that in the article thought doesn't quite couch it in those terms
There is the possibility of triggering a functional deficiency if you take very high doses of B12 - not clear how many people are likely to be affected by this but I'd caution against using very high dose B12 unless you have an absorption problem.
This is the summary document produced by the EFSA (European Food Standards Agency) on vitamin and mineral supplementation and basis for recommendations of upper limits which may be of interest - it's about 10 years old now - the recommendations do get reviewed but I'm not aware of anything that has been changed and you can check the site for yourself.
Thanks. I don't have pa either just b12 deficiency - my doctor has decided that I need injections every three months for the rest of my life. I was on omaprezole (sic) for five years or more. On the Welsh NHS site you directed me to it said that my doctor would monitor me but he didn't - I had a recurring prescription every six months.
I also noted on this site as on the English NHS site that marmite was recommended - I had read that marmite and other vegetable sources of b12 were termed false b12 because the body cannot absorb it.
As I understand (but am no expert):
Marmite is not a vegetable source of B12.
The B12 in Marmite comes from the same sources as other B12 supplements - microorganisms.
Vegetable sources of B12 are things which are similar to "real" B12 but do not have the expected and neccessary effects in the body.
Yes Marmite is good but if you have an absorption problem it will do you no more good than any other B12 rich food - just eat and enjoy it - I do two or three times a week - because I love it 
Thanks for your response. I don't think the reference is to the b12 added to marmite but the belief that yeast based products contain a version of b12 - I read that this is called false b12 because the body cannot absorb it.
Hi Folkstone.
Think this is the section you mean:
What happens if I take too much vitamin B12?
There is not enough evidence to show what the effects may be of taking high doses of vitamin B12 supplements each day.
What does the Department of Health advise?
You should be able to get all the vitamin B12 you need by eating a varied and balanced diet. If you take vitamin B12 supplements, do not take too much, because this could be harmful.
Taking 2mg or less a day of vitamin B12 in supplements is unlikely to cause any harm.
Seems to contradict itself by a) saying not enough evidence to show what the effects may be of taking high doses of vitamin B12 supplements each day and then saying b) if you take vitamin B12 supplements, do not take too much, because this could be harmful.
The reason there is not enough evidence to show that it's harmful is because...there isn't any!
As for the statement that it could be harmful...well, where is the evidence?
High doses of Hydroxocobalamin are give IV for carbon monoxide poisoning (5,000mg x 2 doses, a massive amount, with no harm).
And the neurological regime of 1mg Hydroxocobalamin every other day until no further improvement - for up to two years, as per all guidelines? Well, no harm there 😀.
Also - absorption from tablets 1%. Absorption from injections 100%. Again, no harm with the 100% absorption - so really fail to see the harm in 1% absorption from tablets.
It might reassure you to read the Stitching Tekort document in the third PAS pinned post (to the right of this page when you log on). Research document which highlights that B12 has been found to be safe for the last 50 years.
High levels of B12 that occur where no B12 supplementation has taken place can be indicative of underlying health problems - some of them serious. So, wonder if they're a little confused..
Think I'll email them tomorrow and ask for clarification / evidence. And maybe a page edit 🤔. If...when...I get a response, I'll put it up as a new post.
Good spot eagle eye...😀👍
I've read that blood clots are a risk with B12 supplementation. Of course, being deficient carries many risks as well!
I've read that blood clots are a risk with B12 supplementation.
I've not read anything reliable (i.e., not a blog post) about this.
Hi Statesideheather. Like fbirder , I haven't seen anything reliable about B12 supplementation causing blood clots.
Here's some thoughts (based on reading from reliable sources):
Pernicious anaemia, deficient or low levels of B12, B6 or folate can cause elevated levels of homocysteine. Anaemia can also cause high levels of platelets. Both - or either - of these can increase the risk of blood clotting.
So addressing these deficiencies - in this case, with B12 injections - should return the blood chemistry to 'normal' levels and therefore reduce the risk of clotting.
Elevated levels of platelets can also be caused by, for instance, infection and cancer. And high homocysteine levels can also be associated with heart disease or caused by low levels of thyroid hormones, kidney disease, psoriasis, some medications or rare genetic condition.
So...if B12 supplements do not lower platelets and homocysteine, there may be an underlying condition which leaves an increased the risk of spontaneous blood clots.
This is why it is important for medic's to monitor blood chemistry when treating B12 deficiency (especially in the early stages of treatment). Failure of treatment to return levels of platelet and homocysteine levels to normal should be followed up with further investigations to determine a reason for the continued high levels and the associated clotting risk. Sadly, too few medic's seem to do this 😖.
So...does B12 supplementation itself cause blood clots - don't think so, though It can be argued that people who need it may be more at risk of them. It's also worth noting that not everybody with these type of deficiencies will have an increased risk of spontaneous blood clots - it very much depends on individual blood chemistry.
And if B12, B6 or folate deficiency is found to be the only cause of the elevated levels then once these are treated, the risk should be reduced.
Anyway....just some thoughts that might help 👍
Do B12 supplements distort testing?
B12 deficiency now WHY 
Additional B12 supplements
B12 supplements or B12 shots?
PA and oral B12 supplements
