The trace mineral iodine is well known for its crucial role
in enabling the body's manufacture of vital thyroid
hormones, but it is also important for the health of the
immune system and for optimal brain function. It is widely
believed by many authorities that iodine deficiency should
never be seen in the affluent West, although this problem
affects millions throughout the developed world.
Some nutritionists argue, however, that this conventional
view is too optimistic, because the content of all minerals
in foods is heavily dependent on the mineral content of the
soil from which those foods are derived. The assumption
must therefore be that the continuing de-mineralisation of
farm soils has led to a reduction in the amount of dietary
iodine commonly consumed.
Fish and other seafood, however, remain a relatively rich
source because these ocean creatures concentrate the sea's
iodine in their flesh. Though not commonly eaten in the
West, seaweed, or kelp, is also an excellent source of
iodine for this reason, and is readily available in the
form of a dietary supplements. Dairy products and certain
meats may also be a good source, particularly where iodine
is routinely added to farm animal feed. But in countries,
including most of Western Europe, where animals are grazing
fields growing on iodine depleted soils, levels are likely
to be much lower.
So even in the West, those not including fish or seafood in
their diets, and not using iodised or sea salt, may be at
real risk of deficiency. In an effort to compensate for
low levels of dietary iodine, the mineral has been
routinely added to ordinary table salt in the US for many
years. But the practice is not as common in the UK and
other European countries, where specially iodised or
natural "sea-salt" has been marketed more as a luxury
alternative. The problem of insufficient dietary iodine
has been compounded on both sides of the Atlantic, however,
by increasing concern about the possible adverse health
consequences, particularly high blood pressure, of
excessive salt intake. Many nutritionists, however, regard
these fears as exaggerated, and believe that any such
potential problems are far less serious than the
consequences of an insufficiency of iodine, and may be
easily resolved by the use of the low sodium salt
alternatives available.
Iodine, however, cannot in any case be regarded as a
luxury. Its essential function lies in the production of
the vital thyroid hormones; thyroxine, sometimes known as
T4, and tri-iodothyronine, or T3. And as is well known,
these hormones are crucially important in ensuring a
healthy metabolic rate and the release of energy from food;
so an underactive thyroid gland is commonly the villain in
cases of excessive weight gain, particularly where this of
sudden onset, and in cases of difficulty in losing weight
even when following a sensible reducing programme. A
healthy thyroid gland is also crucial for the optimal
functioning of the immune system.
But perhaps even more importantly, iodine deficiency is
also known as a major cause of avoidable brain damage; a
problem which the World Health Organisation has estimated
to affect an astonishing 50 million people worldwide.
Sadly, many of these cases occur in children whose mothers
were iodine deficient in pregnancy, resulting in a
condition of severely retarded brain development known as
congenital hypothyroidism, or "cretinism". Even where
such catastrophic consequences are avoided, iodine
deficiency in childhood may also have serious effects on
the developing brain, leading to low energy and motivation
for learning, and measurable impairment of IQ scores.
Since 2001 the Food and Nutrition Board of the US Institute
of Medicine (FNB) has prescribed a Recommended Dietary
Allowance for iodine of 150 mcg for all individuals over
14, rising to 220 mcg for pregnant women and 290 mcg for
those breastfeeding. Somewhat confusingly, however, an
excessive consumption of iodine is also associated with a
malfunctioning or enlargement of the thyroid gland, as well
as mouth ulcers, headaches and gastric upsets, and the FNB
therefore advises an upper safe limit for daily iodine
consumption of 1,100 mcg for adults. Most people eating a
conventional Western diet are unlikely to exceed this level.
With the possible exception of pregnant and breastfeeding
women, people in the West who use liberal quantities of
iodised salt as a regular seasoning are unlikely to need
further supplements. But many commercial multi-mineral
preparations contain iodine in reasonable quantities,
usually in the form of potassium iodide, and whilst not
perhaps strictly necessary, such supplementary doses will
do no harm and may be regarded as a useful insurance policy
given that, like all minerals needed by the body, iodine
functions best in the presence of adequate supplies of all
the others. And it should be particularly noted in this
context that the effects of any deficiency of iodine may be
intensified by any deficiency of selenium, iron or vitamin
A.
----------------------------------------------------
Steve Smith is a freelance copywriter and journalist with a
particular interest in health and wellness.
Find out more at
http://www.sisyphuspublicationsonline.com/LiquidNutrition/Io
dine.htm
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