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Iodine deficiency
What everyone
should know
Iodine deficiency – what everyone should know
What is iodine?
You have heard of iodine, of course. But do you
really know how important iodine is for your health?
Whether we feel fit, our babies are born healthy or our
children have normal learning ability - iodine plays a
crucial role throughout. Iodine is essential for healthy
thyroid hormone production. The amount of iodine
needed by your thyroid day to-day is small, but if not
available, it will harm your health. According to the
World Health Organization (WHO; 1994) insufficient
iodine intake is recognized as the most common
Iodine is a natural chemical element, like oxygen, hydrogen
and iron. Iodine is present in some foods naturally, added
to others, and available as a dietary supplement. Due to its
important role in thyroid hormone production, fetal and infant
development; iodine is a crucial nutrient for proper health at
all stages of life.
preventable cause of mental retardation in the world.
International efforts to eliminate iodine deficiency primarily by the WHO, United Nations Children’s Fund
(UNICEF) and the International Council for the Control of
Iodine Deficiency Disorders (ICCIDD) - have dramatically
reduced the population at risk since the early 1990s.
Nevertheless, around the world approximately 2 billion
people including 266 million children of school age
(31.5 %) still suffer from iodine deficiency.1
Iodine is the key component in thyroid hormone production.
When iodine enters the blood stream, the thyroid gland
takes appropriate amounts and converts them into thyroid
hormones: thyroxine (also known as T4) and triiodothyronine
(also known as T3). The T3 and T4 are then released
into the blood and are transported throughout the body.
Thyroid hormones are needed in every single cell of all tissue
and organs. For example, thyroid hormones help the body
use energy, stay warm, and keep the brain, heart, muscles,
and other organs working as they should.2
A teaspoon in a
lifetime…
A teaspoon of iodine is all you need in your lifetime,
however, as the body cannot store iodine for long periods,
tiny amounts are needed regularly.3 The iodine requirements
will change over one’s life depending on age, growth and
special metabolic needs such as pregnancy and lactation.
Several international groups have made recommendations,
which are fairly similar.
This guide has been developed to provide you with all
the important information you need to know about iodine.
Split into helpful sections, it contains specific information
on iodine deficiency and its consequences, tips and
recommendations for women who are pregnant, parents
with young children, and lifestyle related iodine deficiency.
Each section contains a list of useful ‘frequently asked
questions’ which can be used for quick reference.
A helpful list of additional references is also included.
Recommended daily intake of iodine4
When reading this material, please remember that the information
contained herein is intended for general reference only. As a result of
ongoing medical advances and developments, the information herein may
not always be completely up to date and, for this reason, such information
is provided on an “as is” and “as available” basis. Thyroid Federation
International and Merck Serono make no warranties, representations or
gives any undertakings either express or implied about any of the content
of this material. It may refer to pharmaceutical products, therapeutics
or indications not yet registered or approved in a given country.
This information should not be used to diagnose, treat, cure or prevent any
disease without the advice of a qualified medical professional, and does
not replace medical advice or a medical examination.
You must consult a suitably qualified health care professional on any problem or matter
which is covered by any information in this material before taking any action.
Iodine deficiency
What everyone should know
Age
Male
Female
Pregnancy
Lactation
Birth to 6 months
110 mcg*
110 mcg*
7–12 months
130 mcg*
130 mcg*
1–3 years
90 mcg
90 mcg
4–8 years
90 mcg
90 mcg
9–13 years
120 mcg
120 mcg
14–18 years
150 mcg
150 mcg
220 mcg
290 mcg
19+ years
150 mcg
150 mcg
220 mcg
290 mcg
*Adequate Intake (AI): established when evidence is insufficient to develop a RDA (Recommended Dietary Allowance) and is set at a level
assumed to ensure nutritional adequacy.
The World Health Organization (WHO), United Nations Children’s Fund (UNICEF), and the International Council for the
Control of Iodine Deficiency Disorders (ICCIDD) recommend a slightly lower iodine intake for pregnant and lactating women
of 200 micrograms per day.5 Iodine deficiency occurs when iodine intake falls below recommended levels and the thyroid
gland is no longer able to synthesize sufficient amounts of thyroid hormone.
When you are planning for a baby – Iodine comes first
Frequently Asked Questions
When you are planning for a baby, are pregnant or
breastfeeding you need to top up your dietary iodine intake
to produce enough thyroid hormones for you and your baby.
Thyroid hormones, and therefore iodine, are vital to ensure
the normal development of the brain and nervous system.6
Even a mild iodine shortage during pregnancy can have
effects on the delivery and development of a baby, including
hypothyroidism. Adverse effects on early brain and nervous
system development are generally irreversible and can
have serious implications for mental capacity in later life.7
Therefore it is recommended that all pregnant and
breastfeeding women should take a nutritional
supplement containing iodine every day.8 How much iodine do I need?
The iodine requirements will change over one’s life
depending on age, growth and special metabolic needs
such as pregnancy and lactation. Women of childbearing
age should have an intake of 150 micrograms a day.4
This should increase to approximately 250 micrograms
during pregnancy and breastfeeding.13 As your body
cannot store iodine for long periods, it should be supplied
regularly through a healthy diet and the use of iodized salt.
Women of childbearing age should have an average iodine
intake of 150 micrograms per day, which should be increased
to approximately 250 micrograms during pregnancy
and breastfeeding.9 You should take iodine supplements
from the point of planning pregnancy through the full
duration of pregnancy and breastfeeding. If pregnancy is not
planned, you should start taking an iodine supplement of the
recommended amount as soon as possible after finding out.
Because of the potential for side effects and interactions
with medications, you should take dietary supplements
only under the supervision of a knowledgeable health
care provider.
Are you at risk of iodine deficiency?
The only effective prevention of iodine deficiency is
adequate iodine intake. But that’s not always easy with
the normal diet. The last ice age washed iodine out of
the soil and into the sea. Therefore, most natural foods
are low in iodine and most commonly consumed foods
Common Sources of
Dietary Iodine8
To know exactly how much iodine you are getting can be
difficult because the amounts can vary significantly and
are rarely listed on food packaging. But if you don’t eat a
lot of fish and don’t use iodized salt, you could suffer from
iodine deficiency.
provide merely 3 to 75 micrograms per serving4 - except
for seafood, saltwater fish and algae. Seaweed is one of
the best food sources of iodine, but it is highly variable in
its content 10
• Bread
• Cheese
• Cow’s
• Iodized table salt
• Saltwater fish
• Seaweed (including
• Eggs
• Frozen yogurt
• Ice cream
• Iodine-containing
• Shellfish
• Soy milk
• Soy sauce
• Yogurt
milk
multivitamins
Iodine deficiency
What everyone should know
kelp, dulce, nori)
Why is iodine intake in pregnancy so important?
Iodine is essential to make thyroid hormones which
ensure that our bodies run properly. In the first 10–12
weeks of pregnancy the baby is completely dependent
on the mother for the production of thyroid hormone.
After this time the baby is able to produce thyroid hormones
on its own. However, the unborn child remains dependent
on the mother to keep her iodine levels adequate.11
Should I generally take iodine tablets?
No, it is only necessary in certain situations: During
pregnancy and lactation, on low-salt diet, allergies
to fish or when you are on vegetarian or vegan diets.
You should take iodine tablets only after and in
consultation with your physician.
What foods are made with iodized salt for?
Often bread and bakery products are prepared with
iodized salt. Even sausage and meat products may
contain iodized salt. On packaged food, depending on
the country, the iodine content is declared. You can find
the appropriate reference in the ingredients list. When it
comes to non-packaged food, your baker or butcher can
provide information.
Does sea salt contain iodine?
Sea salts and so-called “reform salts” contain, if they are
not iodized, only small amounts of iodine or even none.
To meet the iodine requirements, they do not
contribute significantly.
How much iodized salt?
The WHO recommends a salt intake of less than 5 grams
per day (equivalent to about one teaspoon of salt per day)
to prevent cardiovascular disease.12 5 grams of iodized
salt contain about 100 micrograms of iodine. To meet the
total demand of iodine, you should not eat more iodized
salt, but iodine-rich foods.
How is iodine
deficiency diagnosed?
Since more than 90 % of iodine is excreted in the
urine, the determination of urinary iodine concentration
(UIC) is the most commonly used tool to determine
iodine intake in a population. But it is not a reliable
indicator of an individual’s iodine status; instead, your
doctor will determine your thyroid-stimulating hormone
(TSH) and thyroid hormone (T4) concentrations,
and probably make an ultrasound examination of
your thyroid gland.
Iodine deficiency:
A public health problem throughout the world
How much iodine your
baby needs?
In 54 countries the population has insufficient iodine
intake, according to the WHO.13 Mountainous areas such
as the Alps, Andes, Atlas, and Himalayan ranges and river
valley prone to frequent flooding, especially in South and
Southeast Asia are among the most iodine-deficient regions
in the world.
Infants are at high risk for iodine deficiency because their
need for iodine and thyroid hormone in relation to their weight
is much higher than at any other time in the life.16 When a baby
is exclusively breastfed its iodine intake depends solely of the
iodine concentration of the breast milk, which in turn depends
on the mother’s iodine status. Therefore, the American Thyroid
Association recommends that all breastfeeding women take
a supplement containing at least 150 micrograms of iodine
per day.8 Infants may be at particularly high risk for iodine
deficiency during the weaning period when iodine intake
depends on homemade, age adjusted foods or commercial
complementary formula/foods.16
Median urinary iodine (mcg/l)
Many inland areas, including central Asia and Africa, central
and Eastern Europe, are iodine deficient.17 Iodine deficiency
is defined as a median urinary iodine concentration (UIC)
less than 50 micrograms/l in a population.
iodine intake
iodine status
< 20
insufficient
severe iodine deficiency
20–49
insufficient
moderate iodine deficiency
50–99
insufficient
mild iodine deficiency
100–199
adequate
adequate iodine nutrition
From WHO, ICCIDD, UNICEF14; based on median urinary iodine concentrations of school-age children (≥6 years); applies to
adults, but not to pregnant and lactating women.
What are the symptoms of iodine deficiency?
The wide ranging adverse effects of iodine deficiency,
termed Iodine Deficiency Disorders (IDD) are related to its
effect on the thyroid. The most known and unmistakable
effect of iodine deficiency is goiter, and wherever15
iodine deficiency is common, goiter will be common,
too. This is because the thyroid tries to keep up with
the demand for hormone production stimulated by the
TSH (thyroid stimulating hormone). Like a fisherman
who catches all the more fish, the larger his fishing net
becomes; the thyroid enlarges to filter out as much iodine
as possible from the blood. A goiter is diagnosed by neck
inspection and palpation, and thyroid ultrasonography.
Iodine supplementation by tablets will reduce the size of the
goiter, but often the goiter will not completely dissolve.15
Iodine deficiency
What everyone should know
With insufficient iodine levels hypothyroidism may occur
because iodine is essential for thyroid hormone production.
Iodine deficiency is the most common cause of hypothyroidism
worldwide.8 Hypothyroidism and goiter can occur at any
stage of life, but the most serious consequences of iodine
deficiency occur in women who are pregnant or nursing their
infants, and in children.8 That’s because thyroid hormones
and therefore iodine are essential for normal development of
the brain and the nervous system. When you are pregnant
or lactating, you must get the recommended amounts of
iodine to protect your health and the health of your baby. The
most severe disorder due to severe iodine deficiency during
pregnancy is cretinism, a condition of severely stunted
physical and mental growth. But even mild iodine deficiency
during pregnancy can be associated with low intelligence
in children.8 Sufficient iodine is the best prevention from this
potential complication as well as others, such as stillbirth,
miscarriages or poor growth.8
Iodine-rich mineral water to cover the daily requirement is not
suitable for infants, because most of these waters contain
relatively large amounts of sodium, fluoride, sulfate, or other
unwanted substances. Suitable mineral waters for babies
usually contain only little amounts of iodine and therefore
contribute little to iodine supply.
Too few fish: Iodine
deficiency in children
The favorite foods of children and adolescents are rarely
found in the oceans. Fast food and soft drinks instead of
sea fish and milk, however, do not provide an adequate
iodine intake. Two-thirds of teenagers in the UK are
deficient in the trace mineral, says a new study, partly
because consumption of milk has plummeted in recent
years.17 In children and adolescents, insufficient iodine
and in consequence insufficient thyroid hormones is
particularly serious, because the thyroid hormones have
a decisive influence on the age-appropriate physical
development and maturation processes of the brain.
Iodine deficiency depresses IQ by 10-15 points.18
Even moderate iodine deficiency can have consequences
such as sudden learning difficulties, and poor
concentration. In cases of severe deficiency there may
be slower growth and premature puberty. The good news:
Even severe disorders are improved when the iodine
deficiency in children and adolescents is corrected.19
Frequently asked questions
Can goiter and cretinism be cured?
Cretinism is permanent and incurable, but it is
preventable by sufficient iodine intake during pregnancy.
Certain goiters can be “cured” in the early stages.
Regular intake of iodine, however, prevents goiter
and other iodine deficiency disorders.
Does iodine deficiency affect my child’s
performance in school?
In cases of mild iodine deficiency, even though your child
looks normal, a mild mental retardation may be present.
As we know, children living in iodine-deficient areas
could have a lower IQ level than those living in iodine
sufficient areas; therefore iodine deficiency will affect
school performance.
Checklist
What happens if we get too much iodine?
Most people can tolerate large amounts of iodine
(up to 1000 micrograms a day) without adverse effects.
However, too much and too little iodine are undesirable,
the consequences of iodine deficiency outweigh by
far those of excess iodine. While iodine deficiency can
harm human development and cause irreversible brain
damage, excess iodine may cause stomach ache,
for example. According to ICCIDD properly iodized
salt will rarely add more than about 300 micrograms of
iodine daily to the diet. Therefore, concern about iodine
excess is not a reason to stop or avoid consumption of
iodized salt.20
Do you get enough iodine?
If you eat too little iodine in your diet, your thyroid can become underactive. In the beginning you experience virtually
no symptoms. But when iodine deficiency continues to exist you might experience signs and symptoms that correspond to
the effect of inadequate iodine uptake on your thyroid.
yes
no
Seafood is rather rare in my diet
I rarely use iodized salt
I feel tired and sleepy most of the time
I have little energy
My concentration and memory are poor
I feel unmotivated, sometimes depressed
I am sensitive to cold
Prevention and treatment
of iodine deficiency
Shortage or lack of iodine is not seen individually but on a
population basis. People that live in iodine deficient countries
do not get enough iodine. The same is true for animals living
there and plants growing there. Therefore food from that
region contains little iodine. The best method to cope with
iodine deficiency is long-term dietary supplementation with
iodized salt, the recommended strategy by WHO.1
Where this is not possible well water has been enriched
with iodine or people have been injected with iodized oil.
Thanks to the initiatives by WHO, UNICEF and ICCIDD
the number of world households with access to iodized
salt increased from less than 20% to 70% over the last
two decades.21 Adding iodine to salt remains the most
cost-effective way to control iodine deficiency.
As even a mild iodine deficiency can harm the delivery and
the development of babies, pregnant and breast-feeding
women are advised to take a multivitamin that contains 150
micrograms of iodine per day.4 Considerable progress has
been made ever since the 1990 World Summit for Children
has taken action to eliminate iodine deficiency: Each year
it is estimated 84 million births are protected against brain
damage22 and nearly 91 million children against learning
impairment due to iodine deficiency.21
Iodine deficiency
What everyone should know
I easily catch a cold
I have a tight feeling in my throat
I have difficulties breathing and swallowing
I have a visible swelling at the base of my neck
My skin and hair are dry
I have brittle nails
If you answer 6 of these questions with Yes, you should see your doctor and tell them about your symptoms.
There is a possibility that you aren’t getting enough iodine and your thyroid is not working as it should.
Useful Links
If you want to know more about iodine supply and iodine deficiency you can visit the following websites:
http://www.iccidd.org
The International Council for the Control of Iodine Deficiency Disorders (ICCIDD) is a non-profit, non-government organization for the sustainable
elimination of iodine deficiency and the promotion of optimal iodine nutrition worldwide)
http://www.unicef.org/progressforchildren/2007n6/index_41509.htm
United Nations Children's Fund (UNICEF) publishes “Progress for Children”, a statistical review that documents progress towards
the “Millennium Development Goals”.
http://www.thyroid.org/patients/patient_brochures/iodine_deficiency.html
Patient information on thyroid health published by the American Thyroid Association (ATA)
References
1.
WHO. Iodine deficiency in 2007: Global progress since 2003
http://www.who.int/nutrition/publications/micronutrients/
FNBvol29N3sep08.pdf Accessed November 2011
2.
American Thyroid Association. Thyroid Function Tests. 2005
http://www.thyroid.org/patients/brochures/FunctionTests_brochure.pdf
Accessed November 2011
3.
International Council for the Control of Iodine Deficiency Disorders.
Protecting children http://www.iccidd.org/pages/protecting-children.php
Accessed November 2011
4.
Institute of Medicine of the National Academies. Dietary Reference
Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper,
Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and
Zinc. Washington, DC: National Academy Press, 2001.
Accessed November 2011
5.
International Council for the Control of Iodine Deficiency Disorders.
How much iodine? http://www.iccidd.org/pages/iodine-deficiency/howmuchiodine.php Accessed November 2011
6.
Zimmermann MB (2009) Iodine deficiency in pregnancy and the
effects of maternal iodine supplementation on the offspring: a review.
The AmericanJournal of Clinical Nutrition: 89; 668S-672S.
7.
WHO. Micronutrient deficiencies http://www.wpro.who.int/health_
topics/micronutrient_deficiencies/general_info.htm#idd
8.
American Thyroid Association. Iodine Deficiency
http://www.thyroid.org/patients/patient_brochures/iodine_deficiency.html
Accessed November 2011
9.
The Endocrine Society. Management of Thyroid Dysfunction during
pregnancy and postpartum http://www.endo-society.org/guidelines/
final/upload/Clinical-Guideline-Management-of-Thyroid-DysfunctionduringPregnancy-Postpartum.pdf Accessed November 2011
10. Zimmermann MB. Iodine deficiency. Endocr Rev. 2009
Jun;30(4):376-408
11. American Thyroid Association. Thyroid Disease and Pregnancy
http://www.thyroid.org/patients/brochures/Thyroid_Dis_Pregnancy_
broch.pdf Accessed December 2011
12. WHO. Unhealthy diet. http://www.who.int/gho/ncd/risk_factors/
unhealthy_diet_text/en/index.html Accessed December 2011
13. WHO. Iodine status worldwide. Geneva 2004 http://whqlibdoc.who.
int/publications/2004/9241592001.pdf Accessed November 2011
14. WHO, UNICEF, ICCIDD. Progress towards elimination of iodine
deficiency disorders. Geneva, World Health Organization, 1999
(unpublished document WHO/NHD/99.4); quoted in WHO, UNICEF,
ICCIDD. Assessment of Iodine Deficiency Disorders and Monitoring
their Elimination 2001
http://whqlibdoc.who.int/hq/2001/WHO_NHD_01.1.pdf
Accessed November 2011
15. American Thyroid Association. Goiter http://www.thyroid.org/patients/
patient_brochures/goiter.html Accessed December 2011
16. Zimmermann MB. Low iodine intakes in weaning infants
http://www.iodinenetwork.net/documents/IDD_NL_nov10.pdf
Accessed December 2011
17. Vanderpump MP. Iodine status of UK schoolgirls. The Lancet June
11, 2011; 377
18. http://www.iccidd.org/pages/who-can-prevent-idd/parentsconcernedcitizens.php
19. Markou KB et al. Treating iodine deficiency: Long term effects of
Iodine Repletion on Growth and Pubertal Development in School-Age
Children. Thyroid 2008; 18 (4):449-454.
20. Tulane University. Most frequently asked Questions. A Brief NonTechnical Guide to Ideal Iodine Nutrition
http://www.tulane.edu/~icec/icecfaq.htm
Accessed November 2011
21. UNICEF. Micronutrients - Iodine, Iron and Vitamin A http://www.unicef.
org/nutrition/index_iodine.html Accessed November 2011
22. Experts urge complete global access to iodized salt; prevents
IQ loss and brain damage in babies http://www.physorg.com/
news116687532.html Accessed November 2011
Useful resources
If you would like further information regarding thyroid dysfunction before, during or after pregnancy, please visit:
Patient information provided for
International Thyroid Awareness Week
Patient information by the Thyroid
Federation International
Patient information on thyroid health published
by the American Thyroid Association (ATA)
www.thyroidweek.com
www.web.thyroid-fed.org/en
www.thyroid.org
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