Selenium for Thyroid Hormones
Selenium (Se) for Thyroid
Se need for Thyroid Hormone production
Se is more concentrated in the thyroid
gland than in any other human body organ
Se-dependent selenoprotein enzymes (iodothyronine deiodinases)
required to catalyze the conversion of thyoid hormone T4 to its active form T3 - Since selenium is a component of
deiodinase, low selenium levels means low T3 production. T3 works inside
cells to set the pace of metabolism. (Deiodinase enzymes also control the removal of an
iodine molecule to
convert from T3 to T2 and T2 to T1).
( Se-dependent iodothyronine deiodinase enzymes)
( E.g. Selenocysteine - Selenium combined with the amino acid
Selenoproteins are enzymes that act in various ways to change T4 into
T3 (active thyroid hormone)
and reverseT3 (rT3, which inactivates T3).
selenoprotein enzymes activate and inactivate thyroid hormone, are known
as D1, D2, and D3.
D1 is the
primary activator of thyroid hormone for your body - working mostly in the liver
and to some degree in the kidneys.
D2 is active
in the thyroid gland, brain, nerves, and heart - D2 plays the primary role in thyroid
hormone activation in the brain under normal conditions, and
produces thyroid hormone for the rest of the body under stressed
D3 is mostly a
brake on thyroid hormone activity - turning off
When the body starts to run low on
the activation of thyroid hormone by D1 may drop by 90% and ROS
activity is greatly increased - the body compensates by turning on the back up system, using the
D2 enzyme to maintain active thyroid hormone.The problem with
this back up system running for any great length of time is that is
Even worse, the lack of
increased production of . ROS selenium has already handicapped GSH, the
primary antioxidant that protects
the thyroid gland and liver.Thus, selenium
the body into a very uncomfortable metabolic coping strategy that
eventually leads to slower metabolism, increased
and wear and tear on the thyroid gland and liver.
Se is a component of vital thyroid protective antioxidant Glutathione peroxidase
Intracellular and secreted Se-dependent antioxidant glutathione peroxidases
(GPx) protect thyroid gland from reactive
oxidation species - and in particular, reduce potentially
damaging H2O2 to water.
The enzyme Thyroid PerOxidase (TPO) prepares
iodine for attachment to tyrosine to form
thyroid hormone, a process resulting in excessive numbers of
oxidants such as
hydrogen peroxide and lipid peroxides.
GSH enzymes are proven to protect the thyroid gland (reduce
lipid hydroperoxides to their corresponding
alcohols and free hydrogen peroxide to water) during thyroid hormone formation
(they also help protect the inside of cells, the GI tract and the reproductive
system, and are active in the fluids between cells).
quenching/controlling these potentially harmful oxidants,
GSH enzymes avert thyroid stress and inflammation, which would otherwise retard
thyroid hormone production.
Se is perfect antidote for increasingly present mercury exposure
Mercury is now commonly present in the atmosphere, seafood, dental amalgams,
mercury-laden vaccines - but Se's affinity
for mercury also strips the body of its precious selenium stores.
How much Se do we need?
The average daily intake of Se in U.S. is
Schroeder HA, Frost DV, Balassa JJ. 1970. Essential trace metals in man:
Selenium. J Chronic Dis 23:227-243
Those with thyroid problems, a high mercury
intake/ exposure, or immuno-compromised should ensure a daily intake of 200-400
mcg selenium /day from food or supplementation
seleno-methionine or selenium yeast )
-experts generally agree that one should start supplementation at a 200mcg
dose,increasing dose up to 400 mcg
if symptoms have not not resolved over a few weeks.
NOTE: If you increase your selenium intake
you must also CONCURRENTLY supplement iodine (and vice versa) -
With an iodine
deficiency, any attempts to increase selenium
intake will magnify any
deficiency causing it to become worse . The reverse is also the case.
Foods with high Selenium content
Highest levels of Se found in: brazil nuts
(1 nut fresh from
shell = ~100 mcg), wheat germ,
seafood /shellfish, beef liver and kidney, eggs, sunflower/sesame seeds,
mushrooms, garlic, onions, and kelp.