The enterohepatic circulation of vitamin B-12

[Tony Mach]

I found something very interesting:

The enterohepatic circulation of vitamin B-12 is very important in vitamin B-12 economy and homeostasis (27). Nonvegetarians normally eat 2-6 mcg of vitamin B-12/d and excrete from their liver into the intestine via their bile 5-10 mcg of vitamin B-12/d. If they have no gastric, pancreatic, or small bowel dysfunction interfering with reabsorption, their bodies reabsorb ~3-5 mcg of bile vitamin B-12/d. Because of this, an efficient enterohepatic circulation keeps the adult vegan, who eats very little vitamin B-12, from developing vitamin B-12 deficiency disease for 20-30 y (27) because even as body stores fall and daily bile vitamin B-12 output falls with body stores to as low as 1 mcg, the percentage of bile vitamin B-12 reabsorbed rises to close to 100%, so that the whole microgram is reabsorbed.​

http://www.ajcn.org/content/59/5/1213S.long

Basically, vit b-12 is excreted via bile and the reabsorbed in the gut. The degree of excretion and reabsorption seems to be adjusted with regards to b-12 intake and b-12 status. Now I don't now how fast this adjustment is, but I would imagine it has some lag would explain for me why some changes in nutrition have only temporary improvement, as one might end up with an temporary increased b-12 status after such a change.

 

[LaurieL]

Question for Rich...

I read somewhere, that the enterohepatic circulation once compromised cannot be recovered. Is this true?

LaurieL

 

[richvank]

Question for Rich...

I read somewhere, that the enterohepatic circulation once compromised cannot be recovered. Is this true?

LaurieL

Hi, Laurie.

I assume that you are referring to the enterohepatic circulation of B12 (There are other substances that are involved in this circulation also, such as the bile salts, which are sent back to the liver to be used over again. Various toxins unfortunately can be recirculated this way, also.)

With regard to the B12 enterohepatic circulation, I know that if a person has had surgery that removed their terminal ileum (the last part of the small intestine) there will be a permanent inability to reabsorb B12 and send it to the liver. In some cases of Crohn's disease this is done, for example. Another way there can be a permanent problem is if the cells in the stomach will no longer make intrinsic factor or if the person has developed antibodies that attack intrinsic factor, as in pernicious anemia. But if there is a problem in the gut that can be corrected, I think this circulation can be restored. If it can't, the person can cope in one of three ways: by getting periodic injections of B12, by taking it sublingually, or by taking an oral dose that it 100 times the recommended daily requirement. The third method works because about 1% of the B12 will be absorbed by diffusion through the lining of the gut, without intrinsic factor. B12 is pretty inexpensive, so that can be a practical way to do it.

Best regards,

Rich

 

[Freddd]

Question for Rich...

I read somewhere, that the enterohepatic circulation once compromised cannot be recovered. Is this true?

LaurieL

Hi laurieL,

There is substantial question as to whether once crashed if the enterohepatic cobalamin loop ever gets re-established. There do not appear to be any actual studies of that and everything said appears to be assumption but it mauy also be totally irrelevant. When a person is taking methylb12, and stops, regardless of how much or for how long, symtpomns start returning on generally the 3rd day without methylb12. The symptom free state, maintained on meat alone, does not appear possible after a certain degree of damage and lowering of body b12 levels below a certain point. Whether that is because the enterohepatic loop amount is a mere 10mcg or less per day plus another 6mcg or so from food and that isn't adequate, or because the loop never gets re-established is unknown. It's possible also that the enterohepatic loop has difficulty maintaining a serum level as high as 1000 pg/ml becasue above that the kidneys get rid of cobalamin far more quickly and maybe the damaged body needs a maintained average level of 10,000pg/ml to function. This whole area hasn't been questioned becasue with cyanocobalamin or hydroxcobalamin a body level of 10,000pg/ml of active b12 is impossible and besides, the b12 symprtoms that come back after 3 days are not those relieved by cyanocbl or hydroxcbl, but only those relieved by methylb12. Adenosylb12 symptoms take 2 weeks to a month or more without to start showing up becasue adb12 is parked in the mitochondria and is not the main circulating form whereas mb12 is said to be the main circulating form.

 

[daniariete2000]

Hi ,

becouse of this explanation, could have I any problem with any methylation boosting protocol becouse of I suffer from bile reflux ?

Thanks