Too much B12??: It is my understanding... - Pernicious Anaemi...

However that doesn't mean that supplementation, particularly with large doses, isn't without risk. Many articles seem to confuse the risk with 'toxicity'.

Significant numbers of people seem to respond to raised serum B12 levels in a way that makes the process that allows B12 to move from your blood into your cells much less efficient, so processes stop running effectively and the people concerned experience a functional B12 deficiency.

Functional B12 deficiency is a recognised symptom of some conditions (eg kidney and liver problems) that can lead to raised serum B12 in the absence of any supplementation.

For people with B12 absorption problems the risks of not supplementing with large doses of B12 - B12 deficiency which will lead eventually to multiple system failure and death - considerably outweigh the risks of a functional B12 deficiency from 'over-supplementation'.

If raised serum B12 leads to a functional deficiency because this is about the efficiency with which B12 moves from blood to cells it can be effectively treated by raising serum B12 levels higher to a point where enough B12 does get into cells - or ensuring that supplementation eg by more frequent injections keeps serum B12 levels above the tipping point so enough B12 is always getting through.

Supplementing before confirmation of a B12 absorption problem makes diagnosis of an absorption problem very difficult if not impossible.

garretttimson5 years ago

Dear Gambit62, I appreciate your response. I have attached some links that readers may find interesting. Hypercobalaminemia is associated with some serious underlying pathologies, but these pathologies are not caused by elevated serum (blood) levels of B12, particularly not due to supplementation. Yes, functional B12 deficiency does exist, but

it is not due to over supplementation. There is no replacement for the care of a physician in diagnosing and treating B12 deficiency regardless of the cause. Individuals with longstanding pernicious anemia generally have a handle on monitoring their blood levels and dosing intramuscular B12. For those people, there exists a conversation as to what is a optimal blood level, what form of B12 is most effective (Cyanocobalamin, Hydroxocobalamin, or Methylcobalamin) and is frequency over volume beneficial.

I have been alternating between hydroxocobalamin and cyanocobalamin, and between

5/8 to 1 inch, 25 gauge needle (I don't have much fat on my thigh). I have reduced the quantity per injection from 1000mcg to 700 mcg, but increased the frequency. For years I sailed along at 500 - 600 ng, but due to laxity on my part my level dropped in the 300s, and I started to have a sore tongue. I am now back to actively managing my disease.

academic.oup.com/qjmed/arti...

bloodjournal.org/content/12...

en.wikipedia.org/wiki/Trans...

ghr.nlm.nih.gov/condition/t...