If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.
In case you're looking for a B12 supplement, one of the other MDA forum posters recommended the *methyl* form of B12, which, from reading more about it, appears to be much more effective and bioavailable than other (cheaper) forms of B12. Do a search on iHerb.com to research all of the available options, but here are 2 highly-rated products:
Note that in the Pauling Institute link above, the RDA of B-12 is only 2.4 mcg per day, while further down this page, they note that since even megadoses (e.g. 1000 mcg) haven't been shown to have any toxic effects, there is no established safe Upper intake Level (UL) for B-12. The body simply eliminates any excess that is consumed.
The body is able to store some B12, once it has been absorbed.
As people get older they get worse at absorbing B12, and at converting the usual vitamin tablet form (cyanocobalamin) to the active methyl form.
I concur about Jarrow brand, and put the tablet under your tongue till it melts away. This gets the B12 right into your blood stream, instead of needing "intrinsic factor" in your stomach, which tends to be a problem for anyone with digestive trouble, especially older people.
B12 supports and defends nerve tissue. It is used by every single cell in your body. It is needed to properly make melatonin (in a DARK bedroom) just after you go to sleep. This is often the reason that older people sleep shallowly and not long enough at night. This pattern reversed for me after the FIRST sublingual methyl=B12 tablet. I slept like a log for twelve hours, and woke up feeling sort of molded INTO the bed, for the first time in many years. After two or three days with enough B12 my hours reverted to 7 or 8, because I wasn't as exhausted anymore. Before starting methylcobalamin I always woke up after five or six hours, no matter how tired I still was.
B12 also improves small muscle coordination.
Here's an article about it -- the one which got me to order the Jarrow B12 from vitacost.com.
I third the sublingual B12. After eliminating gluten several years ago and supplementing B12, I noticed feeling considerably stronger. Also, I will have liver every once in a while which is loaded with B12.
Nothing to add to the why or how, given such great responses and links. Regarding testing for B-12 levels, it seems that as with serum testing for magnesium levels, ordinary B-12 blood testing can overlook a lot of pretty significant deficiency states. There is a more accurate but expensive and difficult to find test, the MMA test, but why not just use sublingual methylcobalamin to alleviate any deficiency concerns since there doesn't to be any significant toxicity concern? I know of several people who tested normal for B-12 in standard blood tests, but whose serious medical conditions, including persistently low blood counts, improved dramatically on B-12 supplementation. Deficiencies seem especially common in those with gluten intolerance issues.