From: altar@beaufort.sfu.ca (Ted Wayn Altar)
Subject: Re: vegan sources: B12, D3 and iron
Organization: Simon Fraser University, Burnaby, B.C., Canada
Date: Sun, 30 Aug 1992 20:09:56 GMT

Ted Altar wrote:
>>
>>It is NOT a good idea to take B12 daily, simply because your
>>ability to absorb B12 will decrease with such a surfeit of
>>available B12.  The end result is that you simply become overly
>>dependent on B12 supplements.
>
 
Steve Dyer asserts:
>This is simply not the case.  There is no evidence that taking B12
>causes a reduction un the ability to absorb it.
 
The trouble with stating things so emphatically and absolutely is
that it would ignore the fact that even experts in this field
cannot be so certain that a new paper, or one buried in a less
obvious journal, doesn't provide evidence that you do baldly
claim simply doesn't exist.  Can you really be so certain of
these things?
 
Now, all I have to do is simply cite one reference to refute your
categorical statement, fair enough?
 
My reference, which I listed [Hunt & Groff, 1990], states:
     "Absorption rate of the vitamin decreases with increased
     intake.  At low levels intake, the mean absorption is 70%,
     while at very high levels of intake, the absorption rate
     drops to 16%" [p. 210]
 
Also, take a look at:
 
     See K. McMahon (1987). Coline, an essential nutrient?  NUTR.
     TODAY, 1:95-121.
 
 
 
>>For example, there are trace amounts in some root vegetables (at
>>least on the surface if you don't over scrub your vegetables) and
>>their is good evidence that the b12 which bacteria in our mouth,
>>throat, nasopharynx, around the tonsils and tonsillar crypts, in
>>the folds at the base of the tongue, upper bronchial tree, and
>>the even the small intestine itself where it is absorbed.  Up to
>>.5 mcg at may be obtained this way.
>
>Perhaps, but I wouldn't want to count on that.
 
Not being a vegan, let alone even a vegetarian, you don't have to ;-)
 
 
>
>>In general, women need twice the amount of iron as do men
>>(pregnant woman even several times more than an adult male) but
>>too much iron for men becomes toxic.  Hence, the recommendation
>>to lace everybody's flour with iron was a bad one simply because
>>one half of the population (i.e., women) would benefit while the
>>other half would be at a greater risk of iron toxicity
>>(especially if these men also drink alcohol).
>
>Too much iron for men doesn't get absorbed.  There is absolutely no
>evidence that iron supplementation at the levels found in flour is
>dangerous to men.
 
I think you might be overstating it again, but before I cite some
references first permit me to provide some background for those
readers not familiar with this problem.
 
The classic overload syndrome was first described by Troisier in
1871 and was termed BRONZE DIABETES by him because he had a
patient who died from diabetes mellitus had bronze coloration in
all his tissues.
 
Anatoly Bezkoravainy further points out in his authoritative
"BIOCHEMISTRY OF NONHEME IRON" (1980) that:
      "Today, it is now recognized that iron overload patients
     may develop other complications as well, including
     congestive heart failure, hepatic cirrhosis and fibrosis,
     osteoporosis, and various endocrine gland abnormalities"
 
Primary hemochromatosis affects about 8/1,000. most of these
people having an identifiable genetically transmitted
susceptibility.  Not many to be sure but we must remember that
this figure only pertains to identified cases.  More would
be unidentified (just as we find with diabetes II).  Professor
J. Moon at sfu also suspects that even mild overload over many
years
may be making for some problems in men more frequent than
previously suspected.
 
Childbearing women fortunately tend to be protected from iron
overload due to their monthly menses.  As I mentioned before,
the risk in suspectable individuals increases with alcohol
consumption since alcohol can almost double the rate of iron
absorption in humans.  Hence, absorbable iron from wines is high.
Consequently, South African natives who brew their beer in cast
iron vats have a high incidence of iron overload.
 
Now, in case this gets misconstrued, just because iron absorption
can be increased with alcohol, this should NOT be taken as a
solution to our iron anemia problem among woman, nor as
recommendation to drink more wine.  Remember, other
accompaniments in one's diet, like vitamin C, can increase
absorption greaterfold than even alcohol.
 
Now, down to the issue that you dispute.  In the 1971 FDA
proposal to increase iron in bread and flour by threefold.  This
sparked, as you probably know, much debate  and controversy that
continues today.  Question of efficacy and safety were properly
raised.  For instance, the people who actually are most at risk
of iron anemia tend to not to be the primary consumers of flour,
bread and cereal.  In 1981 the FDA did mandate an increase of
iron fortification by 50%   There is still with us the problem of
widespread iron anemia while at the same time there is the real
and documented *possiblity* of iron over-load in susceptible
individuals due to supplementation in the food supply.  For
evidence on this later point see for example:
 
     W. Crosby (1986).  Yen, Yang and iron.  NUTR. TODAY, 1986,
     21:14-16.
 
     J. Beard (1986).  Iron fortification -- rationale and
     effects.  NUTR. TODAY, 1986, 21:17-20.
 
 
>
>>Undesirable effects from niacin from overdoes via supplements
>>include (1) release of histamine (2) possible injury to the liver
>>(3) raising serum uric acid levels (4) dermatological problems
>>(5) elevation of plasma glucose levels.
>
>This is talking about large doses of niacin, not niacinamide.
>50-100mg+ of niacin will cause transient but harmless flushing.
 
Careful, histamine produced flushing may not only be
uncomfortable but it can be VERY INJURIOUS to persons with asthma
and/or peptic ulcer disease.
 
                                                      ted
 
 

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