QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dunn, J. T. Search for Related Content PubMed PubMed Citation Articles by Dunn, J. T.

---

Supplement: Nutrient Composition for Fortified Complementary Foods

Iodine Should Be Routinely Added to Complementary Foods¹

Department of Medicine, Divisions of Endocrinology and Geographic Medicine, University of Virginia Health System and International Council for the Control of Iodine Deficiency Disorders, Charlottesville, VA 22908

²To whom correspondence should be addressed. E-mail: jtd{at}virginia.edu.

	ABSTRACT

TOP ABSTRACT Does iodine deficiency have... Does iodine excess have... What are the best... Is iodine nutrition an... Recommendations LITERATURE CITED

 
Iodine deficiency has major health consequences for the fetus and infant. Most individuals can tolerate fairly high intakes of iodine without problems. The Western Hemisphere has made great progress towards correcting its iodine deficiency, but pockets of deficiency remain and fragile monitoring systems endanger sustainability. Because the consequences of iodine deficiency are severe and the risks of excess treatment with modest supplements are minimal, we recommend the regular addition of 90 µg of iodine daily to complementary foods for children and 150 µg for pregnant or lactating women, accompanied by effective monitoring of urinary iodine concentration in the population.

KEY WORDS: • iodine nutrition • complementary foods • iodine deficiency disorders

Iodine deficiency exists in most of the world, including the Americas. Until about 1980, virtually every country in the hemisphere except Canada, Chile, the United States and some small Caribbean islands harbored at least some iodine deficiency (1,2). The past two decades have seen great global progress towards iodine sufficiency, principally through the widespread consumption of iodized salt. Still, iodine nutrition can and does fluctuate in many countries in response to changing political and economic conditions, commercial policies, the level of popular interest and natural and manmade disasters.

In this article, we address the issue of iodine in complementary foods by first considering the following questions: 1) Does iodine deficiency have major health consequences for the fetus and infant? 2) Does iodine excess have major health consequences for the fetus and infant? 3) What are the best ways to achieve optimal iodine nutrition? and 4) Is iodine nutrition an important problem in the Americas now?

	Does iodine deficiency have major health consequences for the fetus and infant?

TOP ABSTRACT Does iodine deficiency have... Does iodine excess have... What are the best... Is iodine nutrition an... Recommendations LITERATURE CITED

 
The answer is a resounding "yes." Damaged reproductive outcome is the most important consequence for populations with iodine deficiency (3–6). Iodine is an essential component of the thyroid hormone molecules, consequently insufficient iodine leads to inadequate thyroid hormone production. The fetal thyroid begins functioning around the 12th wk of gestation. Before this and continuing into the second trimester, adequate maternal thyroid hormone is essential for normal human development. A large body of experimental and clinical investigation has established the consequences of iodine deficiency.

Increased neonatal mortality.

Addition of iodine to irrigation water in western China has been associated with a decline in infant mortality to about half the previous average (7). Treatment with oral iodized oil 6–10 wk after birth decreased infant mortality to one-half that of an untreated group in an iodine-deficient region of Indonesia (8). The use of iodized oil in women at an average 28 wk of pregnancy resulted in lower neonatal mortality and higher birth weights than in untreated control subjects (9). Survival to age 15 y for children whose mothers had received iodized oil before or during pregnancy was significantly greater than for untreated controls in New Guinea (10).

Pregnancy complications.

Maternal hypothyroxinemia during the first trimester has been clearly associated with increased pregnancy complications including abortions, breech presentations and fetal abnormalities (4,11).

Brain damage.

Proper development of the brain depends on adequate thyroid hormone. This influence is particularly critical perinatally, a period of very active central nervous system myelination, but it is important throughout pregnancy (4,5,12). The most severe form of brain damage is cretinism characterized by gross mental retardation, deaf mutism, short stature, spasticity and other neuromuscular retardation. Cretinism from iodine deficiency has now become rare because of improved iodine nutrition. However, less obvious damage to the brain occurs with milder degrees of iodine deficiency and is much more extensive within the affected population than is cretinism. This fact has the important public health consequence of putting most people in an iodine-deficient area at some risk for defective brain development. One meta-analysis attributed an average loss of 13.5 intelligence quotient points to iodine deficiency (13). As an example, in the severely deficient village of Jixian in northern China, effective iodization was associated with improved school ranking from 14th (last) in the district to 3rd, decreased school failure rate from 50 to 2%, and 10-fold increases in both the value of farm production and per capita income (14).

Goiter.

The thyroid in iodine deficiency struggles to make adequate thyroid hormone, becoming larger in the process. This goiter is one of the earliest and most visible consequences of iodine deficiency, although it is much less devastating than the damage to reproduction and development. Health consequences of goiter are tracheal obstruction, follicular thyroid cancer and late-onset hyperthyroidism (from autonomous hyperfunctioning adenomas). It also incurs financial burdens; in Germany the annual cost to the health system of iodine-deficient goiter alone has been estimated at over $1 billion (15).

Socioeconomic damage.

The iodine-deficient community collectively risks lower intelligence and more hypothyroidism. In turn, these result in poorer educability and decreased work output (16). The reproductive losses and production of defective offspring drain community resources that could be applied elsewhere. Correction of iodine deficiency has been associated with improved work productivity, educability and economic advancement. Domestic animals, the mainstay of rural economies, share the iodine deficiency of their owners, so agricultural productivity is decreased as well (17).

	Does iodine excess have major health consequences for the fetus and infant?

TOP ABSTRACT Does iodine deficiency have... Does iodine excess have... What are the best... Is iodine nutrition an... Recommendations LITERATURE CITED

 
The short answer is "no." Most humans can tolerate high iodine intakes without problems (18–20). Daily intakes of several mg iodine (10 to 20 times the recommended requirement) usually have no obvious adverse effects. Autoimmune thyroid disease and probably papillary cancer may occur more frequently with higher mean iodine intakes. People who have autonomous nodules and were previously iodine deficient may develop iodine-induced hyperthyroidism upon exposure to normal or high amounts of iodine. All of these complications, although not trivial, are minor compared with the enormous benefits to the community of averting the damaging effects of iodine deficiency. The Tolerable Upper Intake Limits for iodine intake have been set by the Institute of Medicine of the U.S. National Academy of Sciences as 1100 µg/d for adults, 300 µg/d for ages 1–8 y, 600 µg/d for ages 9–13 y and 1100 µg/d during pregnancy and lactation (18). However, these values were developed for iodine-sufficient populations in the United States and are conservative. Other than rare hypothyroidism or goiter from pharmacologic doses of iodine, children and their mothers typically do not have obvious adverse effects from iodine intakes of 1000 µg/d.

	What are the best ways to achieve optimal iodine nutrition?

TOP ABSTRACT Does iodine deficiency have... Does iodine excess have... What are the best... Is iodine nutrition an... Recommendations LITERATURE CITED

 
Several effective means exist for delivering iodine, principally in salt, vegetable oil, water, vitamin-mineral preparations and tablets. Occasionally, local dietary customs have led to other vehicles such as bread, candy, tea and sugar. The best systems deliver iodine at an optimal daily rate, ensure that it reaches the entire target population regardless of geographical or economic isolation, are cost effective in competing with the noniodized vehicle and are safe and sustainable.

Iodized salt can usually meet these qualifications and is the overwhelming favorite for prophylaxis worldwide (21). Successful prophylaxis requires cooperation with the salt trade and regular monitoring. In countries without indigenous salt, appropriate regulations for its importation can make the introduction of iodization fairly simple. On the other hand, iodization is much more difficult to organize in countries with numerous scattered salt deposits and many small traders. Iodization at a level of 20–40 µg/g will deliver iodine adequate to meet most daily recommendations depending on other sources of nutritional iodine, daily salt intake and any losses between production and consumption.

A single dose of iodized vegetable oil (e.g., Lipiodol) delivers a large amount of iodine (200–480 mg) that provides adequate coverage for 6–12 mo (oral administration) or longer (intramuscular administration) (22). Iodized oil can be administered quickly and directly without waiting for changes in the salt trade. The disadvantages are an uneven level of iodine in the body over time and the requirement of direct contact with the individual subject with the accompanying increased costs. Its most frequent use is for immediate action in women and children in areas of severe iodine deficiency. For example, a program in Bolivia in the late 1980s delivered >1.5 million doses over several months to buy time while working through the intricacies of introducing iodized salt into a complex commercial system.

Water, like salt, is a daily necessity for all geographical and socioeconomic levels of the population, and the addition of iodine can produce iodine sufficiency (23). If organic iodine (I₂) is added, it may provide at least some degree of sterilization, an advantage in many communities with the twin problems of iodine deficiency and polluted water. Active programs with iodinated water exist in Mexico and Chile. Water iodized with potassium iodide or potassium iodate is not bactericidal but can provide adequate iodine for nutrition. A few programs in various parts of the world have used this approach (23).

Tablets containing potassium iodide in amounts ranging from 100 to 500 µg are available in some countries (e.g., Germany) where other means for delivering iodine have lagged. Schoolchildren in large parts of the former Union of Soviet Socialist Republics and its allies regularly received iodine supplements, called antistrumin. A study from Zimbabwe found that single oral doses of potassium iodide monthly (30 mg) or biweekly (8 mg) provided adequate iodine for school-age children (24). Lugol’s iodine, containing 6 mg iodine per drop, and similar preparations are widely available as antiseptics in rural dispensaries and offer another simple way to deliver iodine locally.

The selection of a vehicle for iodine is only one component of an effective system for optimal iodine nutrition. Programs that mandate salt iodization but do not provide adequate structural support typically fail (25). Examples include virtually all the salt iodization efforts in Latin America during the 1950s and 1960s (1,2). In addition to an appropriate salt iodization law, programs need a designated responsible body, usually the nutrition division within the Ministry of Health; satisfactory political and budgetary support; an effective working relationship with the salt industry; education for and communication with all relevant targets from politicians to consumers; and a mandated system of monitoring of both people and salt (26).

	Is iodine nutrition an important problem in the Americas now?

TOP ABSTRACT Does iodine deficiency have... Does iodine excess have... What are the best... Is iodine nutrition an... Recommendations LITERATURE CITED

 
The answer is "yes," although progress in the past half century, and especially in the past 15 y, has been enormous (1,2,27). In the mid-20th century virtually every country in Latin America had some degree of iodine deficiency. In the most severely affected areas, the goiter prevalence was 80% and cretins comprised up to 10% of the population. Some success followed the introduction of national salt iodization programs in the 1950s, but it was only partially sustained because of complacency and ineffective monitoring. Interest was revived in the 1980s through the efforts of national governments combined with financial and technical support from the Pan American Health Organization, United Nations Children’s Fund, International Council for the Control of Iodine Deficiency Disorders (ICCIDD), Kiwanis, the bilateral aid organizations of several countries and other groups.

ICCIDD recently summarized the available information (27). Much of the Western Hemisphere’s severe iodine deficiency of the past has been corrected. With the urinary iodine concentration as a yardstick, only 2 (Guatemala and the Dominican Republic) of the 25 largest countries continue to be deficient. Several other countries (Chile, Ecuador and Brazil) risk iodine excess. Despite this progress, monitoring of iodine in people and salt is inadequate, fragile or nonexistent in most countries. ICCIDD estimates that only 5 countries have adequate monitoring by urinary iodine; in another 6, limited monitoring occurs. Similarly, only 5 countries now have adequate monitoring programs for iodized salt, and another 10 have partial monitoring. An important component of a national program, education, was judged adequate in only 2 countries and partial in 6 more. Thus, although adequate iodine nutrition is now fairly good throughout the hemisphere, the means for sustaining it are inadequate and need careful attention. Several countries (e.g., Guatemala, Bolivia and Colombia) have had well-documented fluctuations between iodine deficiency and sufficiency over the years, emphasizing the importance of constant vigilance.

	Recommendations

TOP ABSTRACT Does iodine deficiency have... Does iodine excess have... What are the best... Is iodine nutrition an... Recommendations LITERATURE CITED

 
The above discussion supports the statement in this article’s title that iodine should be routinely added to complementary foods. We have concluded that iodine deficiency has major health consequences for the fetus and infant, that iodine excess is an important but minor issue compared with the consequences of its deficiency, that several good techniques exist for providing adequate iodine and that iodine nutrition remains an important problem in the Americas. Although most of the hemisphere appears to be iodine sufficient, some entire countries and pockets of others remain deficient. Continued monitoring is necessary to obtain more information and to respond to changes such as recent ones in Guatemala and Bolivia.

Food programs should meet the guidelines for recommended daily iodine intakes as set forth by ICCIDD and WHO: 90 µg/d for ages 0–59 mo, 150 µg/d for adolescents and adults and 200 µg/d during pregnancy and lactation (28). These are fairly similar to the recommendations of the Institute of Medicine of the U.S. National Academy of Sciences (18). A small amount of additional iodine (e.g., 150 µg/d) is unlikely to have significant adverse effects in children or their mothers if they are already iodine sufficient. Even when the salt in a country contains adequate iodine, salt intake is frequently restricted during pregnancy and the median national urinary iodine concentration may not reflect the true status for this condition.

From these considerations, we recommend the following: 1) Add 90 µg of iodine per day, in a convenient form, to complementary foods in the diets of children from birth onward. 2) Add 150 µg of iodine to the daily diet of women during pregnancy and lactation, achieved most simply as part of vitamin and mineral supplements. 3) Install effective monitoring by urinary iodine concentration in each country to permit adjustment of iodine nutrition to optimal intakes.

	FOOTNOTES

 
¹ Presented as part of the technical consultation "Nutrient Composition for Fortified Complementary Foods" held at the Pan American Health Organization, Washington, D.C., October 4–5, 2001. This conference was sponsored by the Pan American Health Organization and the World Health Organization. Guest editors for the supplement publication were Chessa K. Lutter, Pan American Health Organization, Washington, D.C.; Kathryn G. Dewey, University of California, Davis; and Jorge L. Rosado, School of Natural Sciences, University of Queretaro, Mexico.

	LITERATURE CITED

TOP ABSTRACT Does iodine deficiency have... Does iodine excess have... What are the best... Is iodine nutrition an... Recommendations LITERATURE CITED

 

1. Dunn, J. T. Medeiros-Neto, G. A. eds. Endemic Goiter and Cretinism: Continuing Threats to World Health 1974 Pan American Health Organization Washington, D.C. .

2. Dunn, J. T. Pretell, E. A. Daza, C. H. Viteri, F. E. eds. Towards the Eradication of Endemic Goiter, Cretinism, and Iodine Deficiency 1986 Pan American Health Organization Washington, D.C. .

3. Dunn, J. T. & Delange, F. (2001) Damaged reproduction: the most important consequence of iodine deficiency. J. Clin. Endocrinol. Metab. 86:2360-2363.[Free Full Text]

4. Glinoer, D. & Delange, F. (2000) The potential repercussions of maternal, fetal, and neonatal hypothyroxinemia on the progeny. Thyroid 10:871-887.[Medline]

5. Delange, F. (2000) Endemic cretinism. Braverman, L. E. Utiger, R. D. eds. The Thyroid. A Fundamental and Clinical Text 2000:743-754 Lippincott Philadelphia, PA. .

6. Delange, F. (2000) Iodine deficiency. Braverman, L. E. Utiger, R. D. eds. The Thyroid. A Fundamental and Clinical Text 2000:295-316 Lippincott Philadelphia, PA. .

7. DeLong, G. R., Leslie, P. W., Wang, S.-H., Jiang, X. M., Zhang, M. L., Rakeman, M., Jiang, J. Y. & Ma, T. (1997) Effect on infant mortality of iodination of irrigation water in a severely iodine-deficient area of China. Lancet 350:771-773.[Medline]

8. Cobra, C., Muhilal, , Rusmil, K., Rustama, D., Djatnika, , Suwardi, S. S., Permaesih, D., Muherdiyantiningsih, , Martuti, S. & Semba, R. D. (1997) Infant survival is improved by oral iodine supplementation. J. Nutr. 127:574-578.[Abstract/Free Full Text]

9. Thilly, C. H., Lagasse, R., Roger, G., Bourdoux, P. & Ermans, A. M. (1980) Impaired fetal and postnatal development and high perinatal death-rate in a severe iodine deficient area. Stockigt, J. R. Nagataki, S. Meldrum, E. Barlow, J. W. Harding, P. E. eds. Thyroid Research VIII 1980:20-23 Australian Academy of Science Canberra, Australia. .

10. Pharoah, P.O.D. & Connolly, K. J. (1994) Iodine deficiency in Papua New Guinea. Stanbury, J. B. eds. The Damaged Brain of Iodine Deficiency 1994:299-305 Cognizant Communication New York, NY. .

11. Allan, W. C., Haddow, J. E., Palomaki, G. E., Williams, J. R., Mitchell, M. L., Hermos, R. J., Faix, J. D. & Klein, R. Z. (2000) Maternal thyroid deficiency and pregnancy complications: implications for population screening. J. Med. Screen 7:127-130.[Abstract/Free Full Text]

12. Stanbury, J. B. eds. The Damaged Brain of Iodine Deficiency 1994 Cognizant Communication Corporation New York, NY. .

13. Bleichrodt, N. & Born, M. P. (1994) A metaanalysis of research on iodine and its relationship to cognitive development. Stanbury, J. B. eds. The Damaged Brain of Iodine Deficiency 1994:195-200 Cognizant Communication New York, NY. .

14. Li, J. & Wang, X. (1987) Jixian: a success story in IDD control. IDD Newsletter 3(1):4.

15. Pfannenstiel, P. (1998) The cost of continuing iodine deficiency in Germany and the potential cost benefit of iodine prophylaxis. IDD Newsletter 14(1):11-12.

16. Dunn, J. T. (1994) Societal implications of iodine deficiency and the value of its prevention. Stanbury, J. B. eds. The Damaged Brain of Iodine Deficiency 1994:309-314 Cognizant Communication New York, NY. .

17. Pandav, C. S. (1996) The economic benefits of the elimination of IDD. Hetzel, B. S. Pandav, C. S. eds. S. O. S. for a Billion. The Conquest of Iodine Deficiency Disorders 1996:129-145 Oxford University Press New Delhi, India. .

18. Institute of Medicine (2001) Dietary Reference Intakes For Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc 2001 National Academy Press Washington D.C.

19. Stanbury, J. B., Ermans, A. E., Bourdoux, P., Todd, C., Oken, E., Tonglet, R., Vidor, G., Braverman, L. E. & Medeiros-Neto, G. (1998) Iodine-induced hyperthyroidism: occurrence and epidemiology. Thyroid 8:83-100.[Medline]

20. Dunn, J. T., Semigran, M. J. & Delange, F. (1998) The prevention and management of iodine-induced hyperthyroidism and its cardiac features. Thyroid 8:101-106.[Medline]

21. Mannar, V.M.G (1996) The iodization of salt for the elimination of iodine deficiency disorders. Hetzel, B. S. Pandav, C. S. eds. S. O. S. for a Billion. The Conquest of Iodine Deficiency Disorders 1996:99-118 Oxford University Press New Delhi, India. .

22. Benmiloud, M., Chaouki, M. L., Gutekunst, R., Reichert, H. M., Wood, W. G. & Dunn, J. T. (1994) Oral iodized oil for correcting iodine deficiency: optimal dosing outcome indicator selection. J. Clin. Endocrinol. Metab. 19:20-24.

23. Iodized water to eliminate iodine deficiency. IDD Newsletter 13(3):33-39.

24. Todd, C. H. & Dunn, J. T. (1998) Intermittent oral administration of potassium iodide solution for the correction of iodine deficiency. Am. J. Clin. Nutr. 67:1279-1283.[Abstract]

25. Dunn, J. T. (2000) Complacency: the most dangerous enemy in the war against iodine deficiency. Thyroid 10:681-683.[Medline]

26. Dunn, J. T. (1996) Seven deadly sins in confronting endemic iodine deficiency, and how to avoid them. J. Clin. Endocrinol. Metab. 81:1332-1335.[Abstract]

27. International Council for the Control of Iodine Deficiency Disorders (2001) The Western Hemisphere nears iodine sufficiency. IDD Newsletter 17(1):1-9.

28. International Council for the Control of Iodine Deficiency Disorders, United Nations Children’s Fund, World Health Organization (2001) Assessment of iodine deficiency disorders and monitoring their elimination. A guide for program managers Second edition 2001 World Health Organization Geneva, Switzerland.

This article has been cited by other articles:

				T. Remer, N. Fonteyn, U. Alexy, and S. Berkemeyer Longitudinal examination of 24-h urinary iodine excretion in schoolchildren as a sensitive, hydration status-independent research tool for studying iodine status Am. J. Clinical Nutrition, March 1, 2006; 83(3): 639 - 646. [Abstract] [Full Text] [PDF]

				C. K. Lutter and K. G. Dewey Proposed Nutrient Composition for Fortified Complementary Foods J. Nutr., September 1, 2003; 133(9): 3011S - 3020. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dunn, J. T. Search for Related Content PubMed PubMed Citation Articles by Dunn, J. T.