B12 Supplement Approx Half Life?

[lownskater52]

Hey everyone,

From my research, I've found the approximate b12 half life to be 6 days. This would mean every 6 days from the day of supplementation, only half of the b12 supplement you took remains in your system. Now I know this is going to fluctuate from person to person but does this sound like a good baseline to establish? I'm 2 weeks into aggresively supplementing b12 with shots and oral supps simultaneously have may have overdone is as I now believe I am hypokalemic. I'll be taking some time off from any supps or shots (1 week) but was interested in the half life.

[JanD236]

I’m sorry I don’t have the answer to your question but I think the important point is, as you say, that it’s going to fluctuate from person to person. Reading through this forum over the last few years it’s clear that different people need different injection frequencies ranging from once or even twice a day to 3 monthly, with every stop in between.

[fbirder]

The pharmacokinetics of B12 are complex. It will have at least three different half lives.

When you first inject (oral supplements are much more complex) the B12 is eliminated in the urine rapidly, while the kidney reabsorption mechanism is saturated, resulting in a very short half life. It also undergoes distribution to various tissues, especially the liver.

Finally, there is the normal elimination half life. This can vary a lot, but it on the order of several months to a couple of years bloodjournal.org/content/bl... . That is why the normal human body can store enough B12 to go four years without consuming any.

You will only become hypokalaemic if you had previously been suffering from megaloblastic anaemia. Have you been diagnosed with this?

[lownskater52 in reply to fbirder]

Hey fbirder, thanks for the input.

I am anemic with low red blood cell count, low hemoglobin, and low hemocrit. Strangely enough, I wasn't megaloblastic anemic when I started supplementing but I am now (high levels of MCH, MCV and MCHC). I made a detailed post with values and an explanation here. Would love some feedback on this too.

healthunlocked.com/pasoc/po...

[fbirder in reply to lownskater52]

No.

Your MCV is not high.

[lownskater52 in reply to fbirder]

Ah so MCV and MCH both have to be higher to be megaloblastic anemic? They are both trending higher even after supplementation. Does that make sense?

[fbirder in reply to lownskater52]

There are other possible reasons for a high MCH and MCHC.

You might, possibly, have macrocytic anaemia if you were also iron deficient. That's because iron deficiency causes microcytic (small cell) anaemia. And the combination of large and small cells will give a result of normal for their average size.

What were you blood levels of B12, folate and iron?

[lownskater52 in reply to fbirder]

Last b12 test (one month ago prior to supplementation) was 159 (low), folate was 16 (good), and iron was 121 (fine)