From: dyer@spdcc.com (Steve Dyer)
Newsgroups: rec.food.veg
Subject: Re: vegan sources: B12, D3 and iron
Keywords: love fest, hell freezing over, smooches all around
Date: 2 Sep 92 03:02:41 GMT
Article-I.D.: spdcc.1992Sep2.030241.4242
Organization: S.P. Dyer Computer Consulting, Cambridge MA

In article <altar.715386425@sfu.ca> altar@beaufort.sfu.ca (Ted Wayn Altar) writes:
>Ok, no need to be shirky.  We are talking at cross purposes,
>and I accept that it is my fault.  Yes, I made a mistake in
>using the word "dependant".  See, I can at least admit to
>being here wrong.
 
Let me pick myself off the floor. :-)

>Now, what I meant to say by my poor and inapposite choice of
>the word, "dependent", was simply the good point that there
>is no advantage to taking daily supplements of B12, that one is
>simply not going to store all of the surplus and that one's
>former, possibly sufficient reliance of even low amounts of
>B12 endogenous in the gut will be changed to a reliance on high
>amounts being ingested, with no real benefit.  Of course, if one
>stops taking the exogenous high doses of B12, then their will
>soon be a feedback, when serum B12 levels drop to a certain threshold,
>to again increase absorption of lower the endogenous and exogenous
>amounts.
 
Well, if you only absorb 10% of 1000 mcg of B12, you're still
absorbing more than 95% of 5 mcg.  Also, I wouldn't be so sure
that this feedback is dependent on serum B12 levels.  It probably
has to do with local absorption and intrinsic factor, etc.

>Now, as I have already said, I am not against judicious use of B12
>supplements but I do think that there is a misunderstanding about
>how to go about doing this.  Many people think, or seem to imply by
>their advice, that one must take supplements of B12 daily or weekly.

The advantage of weekly (or daily) supplementation is that it's
easy to remember for some people and provides a hedge against even
the lowest chance of deficiency.  Less frequent supplementation is
probably just fine.

>I just tried to provide some information to help specify exactly
>how frequently one might take supplements of a certain quantity.
>I trust that even you would agree that it is this kind of concrete
>information that our questioner was probably hoping to receive in
>the first place.
 
No problem.

>>What makes you think I'm not a vegetarian?
>Are you?
 
For the past 6 months, for health reasons (diet and cholesterol).
I very occasionally eat fish and shrimp, though it's not a
primary part of my diet; perhaps every couple of months or so.
I like dairy products, and no-fat skim milk, yoghurt and cottage cheese
are an important part of my diet.  No eggs, unless there's a small
amount in an otherwise low-fat preparation.  I don't really care
what I call myself or what others call me.

>>The rationale for widespread iron supplementation presumably is that
>>the public health benefits of such supplementation outweigh the risks
>>to a small number of individuals.  Healthy men are in no danger of
>>iron overload.
>Let's not forget what this remark was addressing.  You said that
>     "There is absolutely no evidence that iron supplementation
>     at the levels found in flour is dangerous to men."
>Now, I pointed out that there is indeed a possible problem for SOME men.

But these men are going to need treatment anyway.  They're already
getting poisoned by the iron occurring everywhere in their diet.
They're not in a position to act like phenylketonurics and avoid
phenylalanine in the diet.  The treatment in such cases is phlebotomy
and chelation.  They can't control their disorder thru dietary means.

>Of course, we have here the not uncommon dilemma of balancing
>between benefiting the many at he cost of a few.  This is
>essentially a socio-political decision, a decision that is not
>better informed by unguarded remarks like the above.
 
I'm comfortable with it; it's an issue of how qualified you want to
make every remark you make, something I only take so far.  But I did
qualify it in response to your comment.

>Also, the issue of maintaining present levels iron additives in
>foodstuffs is further muddied by the question of "efficacy", as I
>earlier mentioned.  There may well be a better solution for
>addressing this serious problem of iron anemia that is mainly
>prevalent among childbearing women.  For instance, better dietary
>habits, individual supplementation for high risk individuals,
>supplementation for all woman during periods of greater risk,
>better general education on nutrition, greater emphasis in high
>school female health classes on iron anemia, etc.  Look, I'm not
>against general health measures like fluoride being added to city
>water supplies or of their being safe levels of iron being added
>to our foodstuffs, but there some responsible health
>professionals who are NOT convinced that we should solve the iron
>anemia problem simply by further increasing the already possible
>current risk to the few.

But people (mostly men) who are homozygous for hemochromatosis are still
at risk and this risk is stable (100%) until their metabolic derangement
can be noticed and treatment initiated.  There aren't men walking around
who would be asymptomatic except for this extra "push" over the edge.
Heterozygotes appear to have normal iron absorption; it's rather a binary
phenomenon.

I really don't have an opinion about higher iron supplementation,
but I think that this example of hemochromatosis is a bit of a red
herring, if you'll pardon the expression.

-- 
Steve Dyer
dyer@ursa-major.spdcc.com aka {ima,harvard,rayssd,linus,m2c}!spdcc!dyer
Newsgroups: rec.food.veg