My latest blood test showed my B12 at 870. Should I discontinue taking 5,000mg of Methyl B12 or do it every other day?

I read some articles online that claim TOO MUCH B12 can cause blood clots and other problems.

Vitamin B12 and Folate: 870 (range 211-946)
Folate (folic acid), serum: 9.3

--is not very high at all, especially for people who are supplementing.

Did you stop taking your B12 several days before the test was done? That might have given a somewhat more accurate reading; if you were still supplementing right up to the day of the blood test, chances are your B12 had been low for a while. Those of us who supplement with 1000-5000mcg of B12 daily often show much higher levels (my last one was in the 1700's); we often have to explain to not-so-savvy doctors why the levels are that high (and why it's OK--we're supplementing, especially as there are no known toxic levels of B12, with studies from Japan and Europe having given up to 36,000mcg daily with few side effects beyond a little hyperness of energy state).

Mr.s D can probably speak to this better than I can--I can say I haven't heard about high levels of B12 causing blood clots, though. I believe that there are some conditions in which both high B12 and blood clots may be correlated, but some underlying factor is resulting in both.

Can you link to the article that high B12 causes blood clots?
Was it Livestrong? That site is often spotty in its information.

It is important to watch for odd internet sites...that do not have scientific bibliography to corroborate their statements.

This is an example of one that provides a good bibliography:
http://lpi.oregonstate.edu/infocente...ns/vitaminB12/

and:

http://ods.od.nih.gov/factsheets/Vit...hProfessional/

Also a search on PubMed brought up no papers indicating clotting risk.

I did find on Mayo's site... a warning for people with cardiac stents. Because B12 may increase blood cell production, people with stents are to not use really high doses so as not to thicken the blood. The same goes for those with the genetic disease polycythemia Vera, which causes thickened blood with too many red cells. These are special situations, however. A simple CBC will show if there are too many red cells. Just about everyone here has had that test.

Yes, I believe it was Livestrong.

What do you think is a good B12 blood level? 900? 1,000?

Most of us with neuro symptoms keep our level above 1000.
Some more than others.

Going really high is not necessary unless some people have the rare transcobalamin problem. When this is low, transport of B12 is less efficient and it is thought then to keep the blood level higher, to make up for that loss. But the days are early for transcobalamin decisions, so I can't say with certainty yet, since everyone IS different genetically. Tests for transcobalamin are just beginning to be offered.

How long does B12 stay in ones system? If one stopped taking B12, how long before their levels would start depleting and is there a rate of depletion or is that dependent on the person?

On average, what daily amount of Methyl B12 will keep the level above 1000? Once I have taken a starting level, I can have my B12 level tested and go from there. I assume a 90 day period will be sufficient for a beginning test?

Thank you.

Mike