JUL-A-9
AN EXCHANGE OVER IODINE DEFICENCY AND GOITER
WITH A COMPARATIVE BIOLOGIST
Dear Susan:
I will post only a brief
reply, since I am doing this from memory without access to data sources.
Halides generally, and
Iodides specifically are focal in point origins, usually present where there is
or once was a sea salt repository.
There is inadequate iodine in sea water (consider the volume of its
distribution!) and even drinking sea water would be an inadequate way of
getting iodine sufficiency, since it must be concentrated up the food
chain. That is why the repository
source, which I suspect is the residuum less of evaporative large quantities of
sea water, than of decayed organic material leaving behind its elemental iodide
content.
The iodide content of soil,
water, and the subsequent plant or animal ingesters of same varies inversely
with the distance from the sea, with the exception of these point focal
sources, which are actually more enriched than the sea salt.
Other factors enter in,
however, and they include those factors that elute out the very soluble
halides---alternating periods of inundation and dessication---tropical rainy
seasons in areas where salt itself becomes a precious and very perishable
commodity--glaciated (continental or alpine) areas---just look at a map of the
Great Lakes, or Finger Lakes regions in the US alone for geologic evidence---or
volcanic origin soil--magma would be a poor source of iodine.
If you look at interior
continental, alpine or tropical areas with poor soils with very little organic
debris often inundated, and then add some plant origin goitrogens, almost a
definitive picture of Central African, Swiss, Himalayan, US MidWestern or
Andean regions, and you have a snapshot of an endemia of IDD.
Yes, you had sent me your
piece for the Forum, and I do not necessarily agree, first, that Neandertal
were primarily obligate carnivores (consider their dentition as one bit of
evidence) nor, second, that carnivory precludes IDD. That goiter may be rare (but not non-existent) in animal
carnivores, begs too many questions about a whole host of other genetic
set-points for their metabolism rather than their diet, and certainly it is an
easier postulate to make that there may be different handling of iodine among
the different species (beagles are the ones best studied) than to postulate an
intra-species switch in the genetic predisposition for iodine handling (see
below.)
Moreover, I agree that meat
(with the exception of hamburgers made of ground up offal--including the
thyroid "iodine sink" and fed to senor citizens in a nursing home
community--a local mini-epidemic of reported hyperthyroidism in the Dakotas
twenty years ago!) is a poor source of iodine generally, although sea food is
better, the higher on that food chain the better. I have several African examples of goiter in herbivores, and at
least two in carnivores in the same region as my study population.
So, carnivores the
Neandertals may have been (on good days) but I would guess that the majority of
the calories of any hunter-gatherer population is and was still from forager
plant products, with feasts infrequently and famine more regularly. Yes, iodine is excreted on those feast days,
but other than the thyroid--a remarkably efficient concentrator of iodine
against a very steep gradient--the choroid plexus, and the gastric mucosa's
oxyntic cell mass (remember that it is a "halide pump" secreting very
concentrated hydrochloric acid) there
are few other repositories in the body, and the time curve of ingested iodine
decay from loading dose levels is well known--but not by me at this moment
separated from any of my books.
You are aware of the
"stingey gene hypothesis" by African-American investigators who
hypothesize that there is a differential by which
some individuals have the
genetic proclivity to retain salt and calories, and it was the "unnatural
selection" of the Middle Passage in the slave trade that
brought about the paradox
that hypertension and diabetes--nearly unknown at the African points of origin--becomes
a very much higher risk than that for non-black Americans in an environment of
abundance of both--and that within a generation, so it would be too early to
postulate a genetic drift.
It is such a "genetic
switch" that might have given rise to the superior concentration of the
iodine that Jerry Dobson postulated in the minimal shift from metabolism of
Neandertal to Cro-magnon-type moderns to give the energy utilization
differential that would render the former non-competitive.
I will attach a recent
phenomenon in African mal-nutrition and a new wave of epidemic illness foretold
in an editorial requested by the same journal Nutrition as had originally been
the platform for the controversy in the reviews of my paper on IDD.
I recommend a book by Derek
Denton "The Hunger for Salt: An
Anthropological, Physiological and Medical Analysis."
Yes, I would be very
interested in your ideas of funding for further investigation, particularly as
I am now headed out, again, into another IDD endemia in the Himalayas in
Ladakh, "Kingdom in the Clouds"
I may share these thoughts
in response to your query, which may arrive at the same time as my packet of
reprints, with a few colleagues whom you already know, and I wish you well in
your further investigations. I will try
to later access some of the specific data that will support the assertions I am
making now from memory of them.
Cheers!
GWG
>>> Susan Crockford
<scrock@tnet.net> 07/06/01 01:03AM
>>>
Glenn,
I'm really glad your paper
generated a positive response - you deserve it.
It was a really interesting
and well presented piece of research.
Perhaps you could shed some
light on a dilemma that has come up. Were you
given a look at my
contribution to the Forum? In it, I state that since
Neandertals were (by all
evidence) almost exclusively meat-eaters, it would
have been virtually
impossible for them to have been iodine deficient. I
base this on the fact that
ALL vertebrates need iodine for thyroid hormone
just as we do, and that some
of that hormone (along with the iodine) would
remain in muscle tissue,
organs and blood of any kind of animal that was
consumed. As I recall, you
also mention that iodine deficiency is most
rampant in areas where
people have both calorie and protein-deficient diets
- in other words, they are
surviving on minimal nutrients by all counts, and
this is especially
problematic in continental regions. Presumeably in
coastal areas, adequate
amounts of fish and shellfish are usually attainable
by even the poorest
people.
I sent the Forum paper, as a
way of explaining my work and interests, to a
local thyroid disease
specialist here in Victoria (David Derry, with a Ph.D.
in biochemistry as well as
an MD), and we have been chatting back and forth
by email til his schedule
leaves him time to meet face to face. He contends
all his references consider
meat to be a poor source of iodine and figures
that animals from
continental Europe would have even less (he had apparently
read Dobson's paper when it
first came out and followed all of hub-bub
afterward).
Now, as far as I can see,
both things can't be true - something has to be
out of whack here. The soils
of Europe and Africa may be "iodine-poor" but
they must have SOME or no
vertebrates would be able to live there. As far as
I know, no one is reporting
goiters in lions and other carnivores - either
now or in the past. If lions
don't suffer from iodine deficiency, why would
humans eating the same food?
I'm suggesting that the
likely source of the conundrum is either the
relative nature of the
comparison (meat may be "low" compared to seaweed or
fish, but still relatively
good if you're eating alot of it) OR that we
actually need less iodine on
a REGULAR basis than these studies as using as
baselines. The body MUST
store and reuse iodine if it's such an essential
and limiting compound. I see
in your paper that you report the iodine
content of urine, suggesting
that some is actually excreted. Many animals
seek out the urine of other
animals, especially herbivores, and this may be
one way they suppliment
their limited sources of iodine from plant material.
But what is your feeling
about minimal levels of iodine required? Would this
change over time, such that
pound-per-pound children need more than adults?
If adults got a reasonably
big "dose" all at once, say once a week or once a
month, could that last them
til the next time? I guess what I'm wondering is
if this 100 micrograms/day
recommended dose (see below) is a weekly or
monthly need averaged out to
a daily amount for convenience and that this
becomes more than a little
misleading when you try to reconcil it with the
reality of peoples diet.
Derry says that this
"adequate" amount recommended is only just enough to
prevent goiter development
& is considered a "minimum"
ref. cited:
Goodman and Gilman's "The Pharmacological Basis of
Therapeutics. Forth
Edition. The Macmillian
Company Toronto 1970. Page 1478.
Relation of iodine to
thyroid function:
Second paragraph:
"To ensure an adequate
intake (of iodine), which is usually taken to be
about 100 micrograms per
day, one would have to eat about 10 lb of
vegetables or fruit, or 6 lb
of meat or fresh-water fish. Milk and eggs are
somewhat better sources, but
most potable waters contain a negligible
amount."
Any light you could shed on
this would be much appreciated. I'm hoping that
you may have a better
understanding about the total cycling of iodine from
soil to plants to animals to
water, etc. than anyone else. I've just got a
line on some research $$
that might be applicable to some research along
these lines, if you're
interested...
Thanks again for the
goodies.
Susan
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