Joseph Rzeczycki <[log in to unmask]> posted stuff from the Pritikin center
to which I will reply.

> The Brief Response....

>
> First,  B12 is not derived from animal products but is produced by
> bacteria. These bacteria live in animals, including us, the human
> animal.  We produce some B12 each day in our digestive system.

True, but it is not usable because it is produced in the intestines, and to
absorb it it has to first be attached to intrinsic factor, found only in the
stomach.  Hence, for humans to make use of the B12 produced in the
intestines, the intestinal contents would have to back up into the stomach,
then return down again into the small intestine.  In humans, such
regurgitation would be pathological, since the lower sphincter on the
stomach is effectively designed to allow only one way traffic.
>
> Second, allowing for 3-4 oz of animal protein a day and 2 servings a
> day clearly meets the "dietary" requirement for B12.  In addition,
> many food products, such as soy milk, cereal and grain products  that
> many of you may be consuming, are fortified with Vitamin B12.

Many Americans consume that amount of animal protein and fortified products,
but studies are increasingly showing that Americans, especially elderly
Americans, suffer from poor B12 status (not called deficiency, because it
does not involve megaloblastic anemia), affecting nervous and circulatory
systems, despite no lack of intrinsic factor (more on that below), but
simply from inadequate intake, as shown by the fact that oral
supplementation reverses the low status (if intrinsic factor is lacking,
oral supplementation is useless, see below) .
>
> Third, in the U.S., 95% of all cases of B12 deficiency occur in
> the "meat" eating population.  Therefore, a lack of B12 in the
> diet is not always the primary cause of B12 deficiency.

Here the author is referring to the fact that 95% of all reported B12
deficiency cases involve lack of gastric intrinsic factor (proving that
intestinal production of B12 is useless, as noted above).    The important
point here is this:  meat eating is not the cause B12 deficiency, although
the authors crafty draft suggests the opposite.

This is an example of misusing stats.  By dragging out the big "95%" number,
many get the idea that there are lots of reported cases of B12 deficiency
among meat eaters, when in fact clinical B12 deficiency (as identified by
megaloblastic anemia) is rare (and usually due to loss of intrinsic factor
in elderly).

Since more than 95% of people are meat eaters anyway, it is hardly
surprising that 95% of any particular disorder occurs among meat eaters.
The accurate statistic to use here would be the relative incidence of
reported B12 deficiency among meat eaters compared to the relative incidence
of the deficiency among meat avoiders.   Off the top of my head, I don't
know these stats, but for illustration you would be comparing (these figures
are made up) an incidence of 1 case of B12 deficiency in every 100 meat
eaters, and 2 cases in every 100 meat avoiders.  Then you have the
complicating factor that some meat avoiders still eat eggs and/or dairy,
which really are not vegetables and are sources of B12.  So then you have to
find the incidence among animal product avoiders (vegans), etc.

Finally, there is no central agency to which all cases of B12 deficiency are
reported.  Most likely, many cases of B12 deficiency among vegans will never
be reported to a physician, and therefore will never become part of the
statistics.  Here's why:  If someone tries a vegan diet, and over time (say
ten years) develops B12 deficiency, but upon finding himself washed out and
spaced out, he just decides to return to meat eating, without ever going to
a physician to find out what was wrong, or to get the required blood tests,
he does not get counted as a case of B12 deficiency among vegans, even
though he was such a case.  I am certain that this happens many more times
than the opposite case, and so it gives the vegan diet a better appearance
in the stats than it deserves.

> Second, the U.S. sets is level on zinc based on its estimates that
> only 20% of the zinc found in the typical U.S. diet is absorbable.
> The World Health Organization (WHO) bases its zinc recommendations,
> which are much lower  (9.4 for men, 6.5 or women) on people who eat a
> mostly "unrefined" plant based diet (like the diet we recommend).  The
> WHO recommendations for zinc are lower then the USA recommendation
> because absorbability of zinc on such a diet is 30%, 10% higher then
> on a typical US diet.

This is totally wrong.  The WHO standard is lower not because zinc is better
absorbed from unrefined grains (in fact it is the opposite), but because the
WHO is setting minimum standards primarily for poverty striken people who
have little or no hope of meeting any higher standard.  The Nutrition Desk
Reference (NDR) states:  "Anywhere from 20 to 40 percent of the mineral
[zinc] is absorbed from a mixed diet."    Mixed means including meat; so
where did they get the idea that a mixed diet provides only 20 percent
absorption, but an unmixed diet provides better?  None of my nutrition
textbooks have mentioned anything of the sort.

I have never heard of zinc being better absorbed in the presence of
unrefined cereals.  In fact, I have only heard the opposite....again from
the NDR:  "A diet high in cereal and low in animal protein has produced zinc
deficiency symptoms in Middle Eastern populations.   The cause might be a
high phytate diet, in which phytates bind with available zinc and reduce
absorption."

The Pritikin center advocates a high phytate, low meat, low B12,  low zinc
diet and yet claims it is B12 and zinc adequate, and justifies it by
misrepresenting nutritional facts.  I find this to be common among the meat
avoiders.  It is amazing to me how people can so readily believe that
poverty diets are the solution to malnutrition.

Don