iodine deficiency, insufficiency, and public health

Northwestern University Feinberg School of Medicine

Global Iodine DeficiencyEndocrine–Health and SocietyDaniel Toft, MD

Iodine Deficiency

Iodine function: component of thyroid hormones (T3 and T4) which regulate a variety of processes, including:

•Metabolic rate•Heart rate•Temperature•Mental function

Signs and symptoms of iodine deficiency:

• In adults/children: hypothyroidism and goiter (thyroid gland hyperplasia due to elevated TSH levels)

•Congenital hypothyroidism (in fetuses of affected mothers): intellectual impairment, short stature, speech and hearing loss

Beth Doerfler, RD

Iodine Deficiency

Food sources: depends on the iodine content of the soil on which food was raised; good natural sources are seafood and seaweed, and in the U.S., iodized salt, processed foods and dairy products are iodine-rich

Risk factors for deficiency: iodine-poor soil (mountainous areas like Switzerland and the Andes, China), excessive consumption of foods containing goitrogens (which impair iodine absorption), such as cassava (as in Zaire, the Congo)

Beth Doerfler, RD

In 2014 iodine deficiency remains a major worldwide public health problem

A. Strongly Agree

B. Agree

C. Somewhat Agree

D. Neutral

E. Somewhat Disagree

F. Disagree

G. Strongly Disagree

Iodine deficiency is an important health issue for my patients

A. Strongly Agree

B. Agree

C. Somewhat Agree

D. Neutral

E. Somewhat Disagree

F. Disagree

G. Strongly Disagree

Iodine deficiency may impact my health

A. Strongly Agree

B. Agree

C. Somewhat Agree

D. Neutral

E. Somewhat Disagree

F. Disagree

G. Strongly Disagree

Goiter

Beth Doerfler, RD

Himalayas

Goiter

Congenital Hypothyroidism

Congenital Hypothyroidism

Beth Doerfler, RD

Congenital Hypothyroidism

Bolivia TanzaniaPakistan

0 1 2 3 4 5 6 7 8 Birth

Face

Eye

Corpus callosum

Subarachnoid pathways

Cerebral cortex

cochlea

Cerebellum

Dentate of hippocampus

Myelination

from motherfrom child

T4

The Developing Brain Needs T4

Chicago is in the “Goiter Belt”

Defects Found in Drafted Men (Love 1920)

A brief history of goiter• 1813 Iodine isolated from seaweed

• Theodor Kocher (1841-1917), who performed over 5000 thyroidectomies for goiter, recognized post-op myxedema in his patients

• 1873 children in Albi, France treated with 7.5 mg of iodine daily for 75 days with clinical improvement in goiter

• 1893 Thyroid extracts found to be useful in treating myxedema

• 1890s Baumann and Roos isolated “thyroiodine” from the thyroid finding it contained 10% iodine

• Osler writes in the 1900s that the cause of goiter and the function of the thyroid are still unknown

J. Nutr. 135: 675–680, 2005

• 1905 David Marine receives his MD from Johns Hopkins

• 1907 publishes on the iodine content of goitrous dogs vs normal animals finding lower iodine content in goiters

• He began treating patients in his clinic with iodine and noted improvement in goiter

• Cleveland school board rejects his request to begin treating children – “You’ll poison our children”

• 1916 with the help of Kimball Akron, OH agrees to a trial of iodine supplementation to its schoolchildren

Marine And Kimball’s Seminal Work In Akron, OH

J. Nutr. 135: 675–680, 2005

“This section of the country…is known for the great number of goiter cases, and a large percentage of the children in the schools have enlarged thyroids.”

“Iodine is gone from the land here and therefore from the water.”

“In Akron, O., some very fine results have been obtained by giving [iodine] to school children. It was given over a period of ten years and the results watched.

One half of the 10,000 children were given it twice a year. Among those to whom it was administered who were in a normal condition, not one developed goiter.”

The Problems:

There is widespread dietary iodine deficiency •One-half to two-thirds of the world population at risk

In affected populations, goiter and cretinism in a few coexist with cognitive deficits in all

•In populations where >5% of school children have goiter,

the cognitive performance among apparently healthy

individuals is shifted downward by 10 - 15 IQ points

The Solution:

The Solution: Universal Salt Iodization

Key Components of IDD Elimination

Salt Iodization

StrategyOversight

Advocacy & Evaluation &

Social Mobilization Surveillance

Advocacy & Social Mobilization

• Accepting the magnitude of the problem

• Overcoming some resistance to universal salt iodization

• Establishing the safety of potassium iodate

• Setting adequate and safe salt iodine levels

• Salt is not an unhealthy product

• Iodization is enrichment of a commonly eaten food

• Support large companies also, not only the cottage industry

• Focus first on areas where success is attainable, not the poorest and most remote

Strategy Oversight: The Iodine NetworkA global coalition of public, private, international and civic organizationsis championing the sustained elimination of IDD through USI. Currentmembers of the network are:

• China National Salt Industry Corporation

• EU Salt

• Emory University

• Global Alliance for Improved Nutrition (GAIN)

• International Council for Control of Iodine Deficiency Disorders (ICCIDD)

• Kiwanis International

• Salt Commissioner to the Government of India

• Micronutrient Initiative

• Salt Institute

• Tata Chemicals

• US Centers for Disease Control

• UNICEF

• World Health Organization

• World Food Programme

Unicef data

Advocacy & Social Mobilization

In the US, is iodization of salt legally mandated?

A. Of course

B. Of course not

Number Of People And Percent Of Region

At Risk Of Iodine Deficiency (TGR > 5%) And Affected By Goiter In 1993

WHO Region Population At Risk Population Affected by Goiter

Millions % of Region Millions % of Region

AfricaAmericas

E. MediterraneanEurope

Southeast AsiaW. Pacific

181168173141486423

32.823.142.616.735.927.2

86639397176141

15.68.722.911.4139.0

Total 1,572 28.9 655 12

Global prevalence of iodine deficiency disorders (1993)WHO Micronutrient deficiency information system (MDIS) working paper no. 1

“It can do no harm as I see it and its use may do much good.”

Deaths from exophthalmic goiter, 1920-1930

The Economic Effects of Micronutrient Deficiencies:The case of iodine.” by Dimitra Politi, Ph.D., Brown University, 2010.

FIGURE2 A comparison of the number of operations for toxicgoiter carried out at Henry Ford Hospital in Detroit in the years beforeand after the introduction of iodized salt in Michigan in 1924 (-E-); alsothe number of cases presenting with thyrotoxicosis at LauncestonGeneral Hospital before and after the iodization of bread in Tasmaniabegan in 1966 (-F -). The year of introduction is in each case classedas “1”.

J. Nutr. 135: 675–680, 2005

Salt IodizationRussia•Began iodization efforts in 1950s and achieved success•Dissolution of USSR: fragmentation and collapse of iodization program •Small progress recently but household consumption still very low

China•Premier committed to goal of IDD elimination 1991•High level advocacy meeting 1993 launched USI program•Over 90% coverage within a decade

India• Rapid progress 1986-2000 once iodization open to the private sector

• Lifting of ban on sale of non iodized salt in 2000 led to significant drop in production of iodized salt – subsequently recouped when ban was reinstituted

Lessons Learned: Education & Social Mobilization

• As visible forms of iodine deficiency (goiter/cretinism) regress the focus is on less visible impacts especially brain damage. Ongoing communication efforts are essential.

• Tailor messages to different audiences with specific calls to action

• Understand common wisdoms & correct misinformation and educate public

• Integrating updated IDD info into technical & education materials of food inspection, health, and education curriculums

• Public education serves to solidify support for IDD elimination and create a demand for iodized salt

Evaluation & Surveillance

• WHOI 2007 Resolution: Efforts to eliminate IDD require continuous monitoring and oversight and require Member States to establish mechanisms for monitoring iodine nutrition and reporting on their progress.

• UIE trends in school-aged children to be complemented with iodine status of pregnant and lactating women.

• Monitoring of iodine status should not only check for deficiency but also highlight excess.

Source:de Benoist B et al. Iodine deficiency in 2007: Global progress since 1993.Food and Nutrition Bulletin, vol 29, no. 3, 195-202, September 2008.

Category of public health significance (based on median urinary iodine)

Moderate iodine deficiency (20-49 µg/l)

Mild iodine deficiency (50-99 µg/L)

Optimal (100-199 µg/l)

Risk of iodine induced hyperthyroidism (200-299 µg/l)

Risk of adverse health consequences (>300 µg/l)

No data

Degree of public health significance of iodine nutrition based on median urinary iodine: 1993-2006

The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoeveron the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. © WHO 2009. All rights reserved

Overview of Global Progress• Globally, 70% of households are consuming adequately

iodized salt.

• 34 countries have achieved USI and another 28 are close to the goal.

• 84 million infants are protected annually from the risk of IDD.

• More than 120 countries are implementing USI programs.

• The number of countries where IDD remains a problem has dropped to 47.

UNICEF, May 2008

Which best describes your eating habits?

A. I rarely eat a home cooked meal

B. I can cook but generally eat out

C. I cook most of my meals

D. I cook and prefer kosher or sea salt

Emerging Issues: Processed Foods

• Given expanded consumption of process foods, programs relying upon fortification of table salt alone may not be adequate.

• Food processors reluctant to use iodized salt – unfounded concerns about effects on organoleptic properties of foods

• Iodine intake may also be reducing due to other changes e.g. decreased use of iodophors in the dairy industry

• Trade harmonization to mandate use of iodized salt in processed foods to address inter-country variations in micronutrient recommendations may offer a solution.

Emerging Issues: I Insufficiency

Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children

• Urinary iodine levels on 1040 first trimester singleton pregnancies were measured

• 646 (!) were iodine insufficient (urinary iodine less than 150 µg/g creatinine)

• The IQ at 8 years and reading ability at 9 years of the children were analyzed for an association with maternal iodine sufficiency

Lancet 2013; 382: 331–37

Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children

After adjustment for confounders, children of women with an iodine-to-creatinine ratio of less than 150 μg/g were more likely to have scores in the lowest quartile for

verbal IQ (odds ratio 1·58, 95% CI 1·09–2·30; p=0·02)

reading accuracy (1·69, 1·15–2·49; p=0·007)

reading comprehension (1·54, 1·06–2·23; p=0·02)

Lancet 2013; 382: 331–37

Why are UK women iodine deficient?

US Women are Iodine Insufficient

Thyroid. 2013 Aug;23(8):927-37

More Salt May not be the Answer

n % Urinary I p

Salt consumption n % Urinary I p

White Never or rare 142 27 110 .07

Not often 188 27 144

Often 183 36 148

Black Never or rare 77 24 117 .2

Not often 97 30 132

Often 136 46 116

Hispanic Never or rare 78 17 154 .2

Not often 128 27 542

Often 255 56 165

Thyroid. 2013 Aug;23(8):927-37

Neither is Seafood

n % Urinary I p

Fish/shellfish consumption

n % Urinary I p

White Yes 353 71 144 0.6

No 159 29 134

Black Yes 244 82 119 0.5

No 66 18 123

Hispanic Yes 339 73 166 0.03

No 128 27 146

Thyroid. 2013 Aug;23(8):927-37

Dairy consumption matters

Thyroid. 2013 Aug;23(8):927-37

Dairy consumption n % Urinary I p

White Never or rare 149 27 111 0.0001

Not often 167 31 133

Often 216 42 189

Black Never or rare 126 40 111 0.0009

Not often 89 28 109

Often 101 32 151

Hispanic Never or rare 153 31 134 <0.0001

Not often 133 27 163

Often 210 42 185

Group A: ID areas, no iodine intervention

Group B: ID areas, uncontrolled iodized salt

Group C: ID areas, iodine supplements @ pregnancy or birth

Ming Qian et al, Asia-Pacific J Clin Nutr 2005

Areas of Controversy

Should iodine be a required component of prenatal vitamins?

Should iodine and thyroid hormone testing be standard preconception/during pregnancy?

What percentage of the 200+ prenatal vitamins in the US contain iodine?

A. 0 %

B. 20 %

C. 50 %

D. 80 %

E. 100

Conclusions

Conclusions• Iodine Deficiency Disorders are widespread in the world

affecting millions of people with a range of physical and mental abnormalities.

• Universal Salt Iodization (USI) of all human and animal salt is the global strategy for elimination of severe iodine deficiency.

• While tremendous progress has been made to make salt iodization universal, 2 billion people are still at risk in the world

Conclusions• Government Commitment is key for USI

• IDD knowledge needs to be embedded into health sector infrastructure

• Continued advocacy efforts are needed particularly in Europe

• Expand iodization to include salt used in processed foods

• RDA is 150 µg/day for adults; 250 µg/day for pregnant and nursing mothers

In 2013 iodine deficiency remains a major worldwide public health problem

A. Strongly Agree

B. Agree

C. Somewhat Agree

D. Neutral

E. Somewhat Disagree

F. Disagree

G. Strongly Disagree

Iodine deficiency is an important health issue for my patients

A. Strongly Agree

B. Agree

C. Somewhat Agree

D. Neutral

E. Somewhat Disagree

F. Disagree

G. Strongly Disagree

Iodine deficiency may impact my health

A. Strongly Agree

B. Agree

C. Somewhat Agree

D. Neutral

E. Somewhat Disagree

F. Disagree

G. Strongly Disagree