Todd <todd@llama.pasture> wrote in part:

Take for what purpose?
--
Jim Chinnis   Warrenton, Virginia, USA

taking a lot of them?  Does the stuff build up in your system, or do
you
piss away the excess?  Do any metabolites of the B vitamins build up in

your system?  None of the bottles say anything about this, either. <<

COMMENT:

They all seem to be reasonably safe, and none of them build up at doses
below 100 mg a day. If you take less than that, the worst that happens
is you get riboflavin breath, in which your breath and sweat smell like
that smell you smell when you stick your nose into a bottle of
B-complex tabs. Riboflavin (B2) is also the stuff that makes your urine
that fluorescent yellow.

The only really toxic B vitamins are niacin(B3) and pyridoxine (B6).

B3 can cause liver problems at doses larger than 1 gram a day
(niacinamide, which is usually what's in B-complex, is actually a bit
more toxic than nicotinic acid).  Niacinamide at doses less than 500 mg
is pretty benign unless you have liver problems. Of course, there are
histaminic side effects from niacin as nicotinic acid, at doses as low
as 10 mg. But they rarely put this form in B-complex, due to the
unpleasantness of the skin effect (which feels like itch at low doses,
and looks and feels like wholebody sunburn at high ones, but doesn't
last and is harmless).

B6 can cause peripheral nerve damage in doses of grams/day, and there
have been reports as low as 200 mg/day.  I personally wouldn't take
more than 50 mg of the stuff a day. Even 25 mg is 10 times your RDI, so
that has to be overkill.

Some of the B-vitamins seem to have effects which are annoying more
than toxic. And they are person-specific, so I can't claim the
following will happen. Personally, I'm pretty sure than B5 taken in
high dose (500 mg a day) for a long time, then suddenly stopped, gives
me dry eyes for a while. How that works, I cannot say, but it soon goes
away.

Also, 2 B vitamins, B5 and biotin, cause me to have sensitive teeth for
some hours, to the point that I can tell which days I take a B-complex,
and which not. You may or may not find this happens to you. B5 has been
tried on arthritis, and some people complained it actually increased
joint sensitivity. This may be a cholinergic effect. It doesn't seem to
be an inflammatory one, and as noted, is more annoying than anything.
Lastly, something or other in B-complex also seems to be mildly
stimulating like caffeine, and I have more problems with insomnia if I
take it at dinner rather than in the AM.  Again this is mild and only
annoying. It's probably the reason people almost unconsciously tend to
take multivitamins in the AM, especially the megadose ones.

vitamins and what these "dietary supplement" manufacturers think you
should ingest.  All FUD, marketing hype and bullshit aside, what's the
*real* amount of B vitamin supplement that somebody should take? <<

COMMENT:

Nobody really knows. They've tried feeding rats a few times the
equivalent RDI for B-vitamins, and it doesn't lengthen their life span.
There are a few claims for HUGE supplemental doses of a few of the
B-vitamins on rat life span, but they seem to be unrepeatable, or else
everybody would be taking megadoses.

The amount of a lot of the B-vitamins you can absorb at one dose is
limited, though. For B1 and B2 it's around 10 to 20 mg. For B5 and B6
it seems to be larger, but nobody really knows. For most of these
things, absorbed levels are linear up to some limit of gut transporter
overload (like 20 mg) then go up in log fashion from there, probably
due to direct mass-action diffusion absorption.

SBH