Can I replace 10 weekly injections with 1000micro gram tablets daily.A PMJ paper from 2003 suggested this was efficacious.

[RonnyP]

Recently been encountering resistance to getting injections at 9 to 10 weeks intervals.

A Med professional (retired) dug out the paper "Oral vitamin B can change our practice" has any one got experience of doing this substitution. And why has this not been more widely adopted.

Sincerely RonnyP

[clivealive Forum Support]

Hi RonnyP the latest BNF guidelines allow injections every eight weeks for patients with neurological symptoms.

bnf.nice.org.uk/drug/hydrox...

As I understand it if you have an absorption problem with your digestive system oral B12 will be of little use.

I am not a medically trained person but I've had Pernicious Anaemia (one of many causes of B12 deficiency) for more than 46 years.

I wish you well.

[Gambit62 Administrator]

2003 is a very old paper in terms of research.

There are a number of studies suggesting that very high dose B12 can be effective in maintaining B12 levels in patients with absorption problems post loading doses but they also show that they don't work for everyone.

There are also some studies showing that they may not be as effective as people think - from measuring MMA and homocysteine levels for people on high dose oral compared to those on injections.

ncbi.nlm.nih.gov/pubmed/284...

full article available here

smw.ch/article/doi/smw.2017...

The therapy is based on the use of 'passive absorption' which happens outside the ileum and the areas generally affected by B12 absorption problems and seems to count for about 1% of absorption on average- but this also varies considerably from individual to individual.

[bquoss]

Hello, RonnyP. There are many studies about high dosage oral B12, but they all use blood levels of B12 as the measure. The problem is that you can have neurological symptoms with a normal blood level of B12. So I personally think these studies are dangerous. The best way I found to counter a doctor who spoke about those studies was to provide information about neurological symptoms and blood level measures. This site has good information from the Pernicious Anemia Society that I used. I wish you well.

[fbirder]

It's not been widely adopted because it don't work in patients.

I've not found any reliable studies where they looked at people with a definite diagnosis of Pernicious Anaemia. Most of them tend to use people with a B12 deficiency, with no attempt to find the cause of that deficiency - they just assume its PA.

Of course, if you have low B12 for some other reason, especially if your diet is deficient in B12, then an oral dose will be perfectly effective.

And the fact that they report about 10% absorption also makes me suspicious. The Intrinsic Factor transport mechanism has a limited capacity - on the order of 10 mcg in a single meal. And these studies nearly always use a high dose of 1000 mcg.

If you gave a normal person 1000 mcg of B12 then, because of the limited capacity for absorption via IF, you would expect them to absorb about 10 mcg - or 1% of the dose.

[helvella in reply to fbirder]

Isn't the argument that high dose oral B12 can diffuse rather than be carried by IF?

(Mind, I still don't believe that 10% can be taken in, regardless of how it is transported.)

[fbirder in reply to helvella]

Yes, that is the argument.

However, it's a very weak argument.

The B12 molecule is too large to easily pass across biological membranes without help. Otherwise it wouldn't need the complicated IF transport mechanism.

If B12 could easily pass across the gut wall then the B12 made by the bacteria that live in the large intestine could be absorbed. We wouldn't need to consume B12 in our food. We would be like cattle.

If B12 could easily pass across mucous membranes then B12 suppositories would be a thing. B12 in a suppository would be in contact with a membrane for many hours - greatly increasing the amount that could be absorbed compared to sublingual B12. There's a patent application for B12 suppositories. It never got anywhere, suggesting it don't work.