Iodine for health - Goitrogens compete with Iodine
Goitrogens vs. Iodine
What are Goitrogens?
Goitrogens are substances that interfere with the body's
uptake and utilization of iodine
In the thyroid , goitrogens slow down
the thyroid's thyroid hormone (TH) production by blocking its access to iodine or
disrupting communication with thyroid cells. This
can result in a failure of the auto-regulating feedback loop for T4/T3 synthesis
and/or the inability to utilize available iodine.
Consequentially, due to incomplete thyroid hormone synthesis, the thyroid follicles
continue to fill with an excessive amount of colloid thyroglobulin that has
not been made into TH. This is seen as a lump on the front base of the neck - called
a goiter.
Goiter
Goitrogens include:
(1) The halogens: bromine,
fluorine, chlorine which compete with
iodine for the
body's cell receptors. In an iodine-deficient person this could:
• Cause
Thyroid dysfunction. By slowing TH production (insufficient
iodide interferes with formation/function of thyroglobulin);
normal saliva to blood iodide ratio is
about 42, but is lowered to < 20 when very high levels of bromide/fluoride bind
to the symporter pumps that take iodine into the
cells (i.e. more iodide is left in the blood).
• Reduce
hydrochloric acid production in the stomach. By causing
iodide -pumps to malfunction.
(2)
Isoflavones and isothiocyanates in certain foods. E.g. excessive
coonsumption of soybeans (and products), cruciferous vegetables - prevent
iodine addition into thyroid hormones
(3) Certain drugs.
E.g. thiouracil and sulfonamides
Goitrogenic halogens have become excessively common in today's
world
In addition to
iodine , there
are 4 other halogens (group 17 of the periodic table).
These are bromine, fluorine, chlorine
and less biologically relevant astatine (of
which only iodine and
chlorine are essential to the body). In recent
decades, these halogens have majorly infiltrated our lives.
Halogen Invasion
A certain level of
iodine is needed to prevent unwanted halogens occupying
available halogen receptors. E specially in the case of
bromine.
Tests have proven an
iodine dose of 12.5 mg/day
adequate to remove fluorine (in non-heavy fluoride consumers),
but at least 20mg/day is needed to dislodge bromine quickly.
- A person needs to have sufficient protein
and Vitamin C to deal with the influx
of iodine which becomes available
for utilization as the bromine and fluorine are being pushed out; the
body uses the protein sodium iodide symporter
for iodine transport into cells. Dr. Abraham has
shown that Vitamin C is helpful in supporting
this pump.
Nitty gritty:
iodide
must bind to a halide symporter binding site before cellular uptake via the
iodine pump. Goitrogenic substances compete with
iodide for these binding sites. These "iodide
transport/utilization inhibitors" interfere with iodide
transport at the cell membrane in several organs at sites of
iodide oxidation and utilization.
Certain foods naturally contain goitrogens
Certain foods contain goitrogenic isoflavones
and isothiocyanates associated with decreased thyroid function.
I soflavones are a member of the health-supportive,
antioxidant flavonoid family, that give virtually
all plants their vivid array of colors. Isoflavones, such as genistein in soy, have
been found to:
(i) Block the activity
of the thyroid peroxidase (TPO) enzyme.
Necessary for adding iodine into thyroid
hormones;
(ii) Disrupt messages
across thyroid cell membranes;
- Cruciferous vegetables
(contain isothiocyanates). Members of the
Brassicaceae family (includes broccoli, cauliflower, Brussels
sprouts, cabbage, mustard, rutabagas, cassava root, kohlrabi and turnips); crucifers
also naturally produce the iodide competitor methyl
bromide;
- Soybean foods
(contain isoflavones). These includes soybeans, soy extracts, tofu,
tempeh, soybean oil; contain the isoflavones genistein and daidzein, and glycitein.
- Some other foods.
E.g. peaches, strawberries, millet, pears, peanuts, radishes, spinach, pine nuts,
bamboo shoots and sweet potatoes
Obviously these goitrogenic foods are healthy,
nutritious foods when eaten in moderation, but you may be getting more soy than
you thought. It is their
overconsumption that would be a problem for individuals
with thyroid hormone deficiency; overconsuption of crucifers is unlikely, but soy
appears in many packaged food products in many forms, such as soybean oil, textured
vegetable protein (TVP) and isolated soy concentrate;
Cooking inactivates about one third of goitrogenic
effect. B oth isoflavones (in soy foods) and isothiocyanates
(in cruciferous vegetables) appear to be heat-sensitive;
Certain drugs are goitrogenic
E.g. thiouracil and sulfonamides