Iodine as Essential Nutrient during the first 1000 Days of Life
Iodine is an essential nutrient, particularly crucial for neurodevelopment. Iodine deficiency during pregnancy and maternal hypothyroxinemia can negatively impact brain development and neuro-behavioral performance postnatally.
Source: Velasco et al. Nutrients, 2018. https://www.mdpi.com/2072-6643/10/3/290/htm
- Iodine is an essential nutrient, particularly crucial for neurodevelopment.
- The first 1000 days of life have been established as a “window of opportunity” for potential interventions able to determine crucial pathways of human growth and development.
Cow Milk Consumption Increases Iodine Status in Women of Childbearing Age in Randomized Controlled Trial
A randomized controlled trial found that the consumption of additional cow’s milk can significantly increase urinary iodine concentration in women of childbearing age. These results suggest that cow’s milk is a potentially important dietary source of iodine in this population group. Cow milk contributes the greatest amount to iodine intakes in several countries.
Source: O’Kane et al. J Nutr, 2018. https://doi.org/10.1093/jn/nxx043
- Cow’s milk is a potentially important dietary source of iodine for women of childbearing age. Cow’s milk contributes the greatest amount to iodine intakes in several countries.
- Within the context of a public health strategy designed to reduce the prevalence of iodine deficiency, an increase in milk consumption could represent an important contribution.
Study analyzed mother–child pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort by measuring urinary iodine concentration (and creatinine to correct for urine volume) in stored samples from 1040 first-trimester pregnant women. 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, reading accuracy, and reading comprehension than were those of mothers with ratios of 150 μg/g or more. Our results show the importance of adequate iodine status during early gestation and emphasize the risk that iodine deficiency can pose to the developing infant, even in a country classified as only mildly iodine deficient. Iodine deficiency in pregnant women in the UK should be treated as an important public health issue that needs attention.
Source: Bath SC et al. Lancet, 2013. https://doi.org/10.1016/S0140-6736(13)60436-5
- Research supports the importance of adequate iodine status during early gestation and emphasize the risk that iodine deficiency can pose to the developing infant, even in a population classified as only mildly iodine deficient.
Mild Iodine Deficiency During Pregnancy is Associated with Reduced Educational Outcomes in the Offspring: 9-Year Follow-Up of the Gestational Iodine Cohort
A longitudinal follow-up (at 9 years old) of the Gestational Iodine Cohort found that children whose mothers had UIC <150 μg/L had reductions of 10.0% in spelling, 7.6% in grammar, and 5.7% in English-literacy performance compared with children whose mothers' UICs were ≥150 μg/L. These associations remained significant after adjustment for a range of biological factors. Differences in spelling remained significant after further adjustment for socioeconomic factors.
Source: Hynes KL et al. J Clin Endocrinol Metab, 2013. https://doi.org/10.1210/jc.2012-4249
- Emerging evidence shows that even mild iodine deficiency during pregnancy can have long-term adverse impacts on fetal neurocognition that are not ameliorated by iodine sufficiency during childhood.
Key Findings From Provided Resources
Iodine intake amongst women of childbearing age in the UK
- Women entering pregnancy need to have adequate iodine status to ensure optimal fetal neurological development and pregnancy outcome.
Some subgroups of reproductive age women in the United States may be at risk for iodine deficiency
- Consuming an adequate amount of iodine during pregnancy is critical for fetal neurologic development.
- Even a mild deficiency can impair cognitive ability.
- Important sources of iodine in the United States include dairy products and iodized salt.
- Dairy product consumption may be an important contributor to iodine status among both pregnant and nonpregnant, nonlactating women. Those who do not consume dairy products may be at risk for iodine deficiency. Although larger samples are needed to confirm these findings, these results raise concerns about the iodine status of pregnant women and women of reproductive age who are not consuming dairy products.
Mild to moderate iodine deficiency affect thyroid function in pregnancy
- Studies indicate that mild to moderate iodine deficiency in pregnancy may have a long-term negative impact on child neurodevelopment.
- Results of this study indicate that mild to moderate iodine deficiency affect thyroid function in pregnancy.
Overview of the disorders caused by iodine deficiency. It emphasizes the role of iodine deficiency in the development of brain damage and neurocognitive impairment
- Major dietary sources of iodine in the USA, Europe and Australia are bread, milk and to a lesser extent seafood.
- The consequence of iodine deficiency during pregnancy is impaired synthesis of thyroid hormones by the mother and the fetus. An insufficient supply of thyroid hormones to the developing brain may result in neurocognitive impairment
Disorders of the Thyroid Gland in Infancy, Childhood and Adolescence
Key findings: n/a
ADDITIONAL RESEARCH, KEY FINDINGS & RESOURCES
Iodine facts for health professionals, from the National Institutes of Health
- Iodine is a trace element that is naturally present in some foods, added to others, and available as a dietary supplement. Iodine is an essential component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Thyroid hormones regulate many important biochemical reactions, including protein synthesis and enzymatic activity, and are critical determinants of metabolic activity [1,2]. They are also required for proper skeletal and central nervous system development in fetuses and infants .
- Iodine may have other physiological functions in the body as well. For example, it appears to play a role in immune response and might have a beneficial effect on mammary dysplasia and fibrocystic breast disease .
- According to the WHO, a median urinary iodine concentration of 150–249 mcg/L indicates adequate iodine nutrition during pregnancy, while values less than 150 mcg/L are considered insufficient [3,7]. Analyses of NHANES datasets covering time periods from 2001 to 2008 indicate that a substantial portion of pregnant women in the United States are iodine insufficient.
- Pregnant women who do not consume dairy products may be particularly at risk of iodine insufficiency. According to NHANES 2001–2006 data, pregnant women who consumed no dairy products in the previous 24 hours had a median urinary iodine concentration of only 100 mcg/L, compared with 163 mcg/L among consumers of dairy . Women who restrict their dietary salt intake also have lower urinary iodine concentrations and might be more likely to be iodine deficient than women who don’t restrict salt intake .
- Due to its important role in fetal and infant development and thyroid hormone production, iodine is a critical nutrient for proper health at all life stages.
- Iodine sufficiency during pregnancy is extremely important for proper fetal development. During early pregnancy, when fetal thyroid gland development is incomplete, the fetus depends entirely on maternal T4 and therefore, on maternal iodine intake . Sufficient iodine intake after birth is also important for proper physical and neurological growth and maturation.
- Intake recommendations for iodine and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences) . DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and gender , include:
- Recommended Dietary Allowance (RDA): Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.
- Adequate Intake (AI): Intake at this level is assumed to ensure nutritional adequacy; established when evidence is insufficient to develop an RDA.
Table 1: Recommended Dietary Allowances (RDAs) for Iodine 
|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||220 mcg|
|19+ years||150 mcg||150 mcg||220 mcg||220 mcg|
* Adequate Intake (AI)
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 higher iodine intake for pregnant women of 250 mcg per day [3,7].
- Seaweed (such as kelp, nori, kombu, and wakame) is one of the best food sources of iodine, but it is highly variable in its content . Other good sources include seafood, dairy products (partly due to the use of iodine feed supplements and iodophor sanitizing agents in the dairy industry ), grain products, and eggs. Dairy products, especially milk, and grain products are the major contributors of iodine to the American diet . Iodine is also present in human breast milk [2,5] and infant formulas. Fruits and vegetables contain iodine, but the amount varies depending on the iodine content of the soil, fertilizer use and irrigation practices .
- Important to note regarding the iodine status of the general US population: Since the inception of the NHANES monitoring program, urinary iodine measurements have shown that the general U.S. population is iodine sufficient. This is despite the fact that urinary iodine levels decreased by more than 50% between 1971–1974 and 1988–1994 [2,23]. Much of this decline was a result of decreased levels of iodine in milk due to the reduced use of iodine-containing feed supplements and iodophor sanitizing agents in the dairy industry , as well as the reduced use of iodate dough conditioners by commercial bakers. (Milk’s content of iodine is varied based on iodine in feed and in processing practices).
Table 2: Selected Food Sources of Iodine [10,11,12]
|Food||Approx. Micrograms (mcg) per serving||Percent DV*|
|Seaweed, whole or sheet, 1 g||16 to 2,984||11% to 1,989%|
|Cod, baked, 3 ounces||99||66%|
|Yogurt, plain, low-fat, 1 cup||75||50%|
|Iodized salt, 1.5 g (approx 1/4 tsp.)||71||47%|
|Milk, reduced fat, 1 cup||56||37%|
|Fish sticks, 3 ounces||54||36%|
|Bread, white, enriched, 2 slices||45||30%|
|Fruit cocktail in heavy syrup, 1/2 cup||42||28%|
|Shrimp, 3 ounces||35||23%|
|Ice cream, chocolate, 1/2 cup||30||20%|
|Macaroni, enriched, boiled, 1 cup||27||18%|
|Egg, 1 large||24||16%|
|Tuna, canned in oil, drained, 3 ounces||17||11%|
|Corn, cream style, canned, 1/2 cup||14||9%|
|Prunes, dried, 5 prunes||13||9%|
|Cheese, cheddar, 1 ounce||12||8%|
|Raisin bran cereal, 1 cup||11||7%|
|Lima beans, mature, boiled, 1/2 cup||8||5%|
|Apple juice, 1 cup||7||5%|
|Green peas, frozen, boiled, 1/2 cup||3||2%|
|Banana, 1 medium||3||2%|
*DV = Daily Value. The U.S. Food and Drug Administration (FDA) developed DVs to help consumers compare the nutrient contents of products within the context of a total diet. The DV for iodine is 150 mcg for adults and children age 4 years and older . FDA does not require food labels to list iodine content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient, but foods providing lower percentages of the DV also contribute to a healthful diet.
The U.S. Department of Agriculture’s (USDA’s) National Nutrient Database  does not list the iodine content of foods or provide lists of foods containing iodine.
1. National Research Council, Committee to Assess the Health Implications of Perchlorate Ingestion. Health Implications of Perchlorate Ingestion. Washington, DC: The National Academies Press, 2005.
2. Institute of Medicine, Food and Nutrition Board. 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.
3. World Health Organization. United Nations Children’s Fund & International Council for the Control of Iodine Deficiency Disorders. Assessment of iodine deficiency disorders and monitoring their elimination. 3rd ed. Geneva, Switzerland: WHO, 2007.
4. Patrick L. Iodine: deficiency and therapeutic considerations. Altern Med Rev. 2008 Jun;13(2):116-127. [PubMed abstract]
5. Zimmermann MB. Iodine deficiency. Endocr Rev. 2009 Jun;30(4):376-408. [PubMed abstract]
6. Zimmermann MB, Jooste PL, Pandav CS. Iodine-deficiency disorders. Lancet. 2008 Oct 4;372(9645):1251-1262. [PubMed abstract]
7. WHO Secretariat, Andersson M, de Benoist B, Delange F, Zupan J. Prevention and control of iodine deficiency in pregnant and lactating women and in children less than 2-years-old: conclusions and recommendations of the Technical Consultation. Public Health Nutr. 2007 Dec;10(12A):1606-1611. [PubMed abstract]
8. Pennington JA, Young B. Iron, zinc, copper, manganese, selenium, and iodine in foods from the United States Total Diet Study . J Food Compost Anal. 1990 June;3(2):166-184.
9. Murray CW, Egan SK, Kim H, Beru N, Bolger PM. US Food and Drug Administration’s Total Diet Study: dietary intake of perchlorate and iodine. J Expo Sci Environ Epidemiol. 2008 Nov;18(6):571-580. [PubMed abstract]
10. Pennington JAT, Schoen SA, Salmon GD, Young B, Johnson RD, Marts RW. Composition of Core Foods of the U.S. Food Supply,III. Copper, Manganese, Selenium, and Iodine . J Food Comp Anal. 1995;8(2):171-217.
11. Teas J, Pino S, Critchley A, Braverman LE. Variability of iodine content in common commercially available edible seaweeds. Thyroid. 2004 Oct;14(10):836-841. [PubMed abstract]
12. Dasgupta PK, Liu Y, Dyke JV. Iodine nutrition: iodine content of iodized salt in the United States. Environ Sci Technol. 2008 Feb 15;42(4):1315-1323. [PubMed abstract]
13. U.S. Food and Drug Administration. Food Labeling: Revision of the Nutrition and Supplement Facts Labels. 2016.
14. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central , 2019.
15. U.S. Food and Drug Administration, Code of Federal Regulations, CFR 21, SectionsandRevised April 1, 2009.
16. Aquaron R, Delange F, Marchal P, Lognoné V, Ninane L. Bioavailability of seaweed iodine in human beings. Cell Mol Biol (Noisy-le-grand). 2002 Jul;48(5):563-569. [PubMed abstract]
17. Pennington JA, Young BE, Wilson DB. Nutritional elements in U.S. diets: results from the Total Diet Study, 1982 to 1986. J Am Diet Assoc. 1989 May;89(5):659-664. [PubMed abstract]
18. Pennington JA, Young BE. Total diet study nutritional elements,J Am Diet Assoc. 1991 Feb;91(2):179-183. [PubMed abstract]
19. Centers for Disease Control and Prevention (CDC). National Center for Health Statistics (NCHS). National Health and Nutrition Examination Survey Data . Hyattsville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. Accessed 11/14/2009.
20. Ristic-Medic D, Piskackova Z, Hooper L, Ruprich J, Casgrain A, Ashton K, Pavlovic M, Glibetic M. Methods of assessment of iodine status in humans: a systematic review. Am J Clin Nutr. 2009 Jun;89(6):2052S-2069S. [PubMed abstract]
21. Zimmermann MB. Methods to assess iron and iodine status. Br J Nutr. 2008 Jun;99 Suppl 3:S2-9. [PubMed abstract]
22. Caldwell KL, Miller GA, Wang RY, Jain RB, Jones RL. Iodine status of the U.S. population, National Health and Nutrition Examination Survey. 2008 Nov;18(11):1207-1214. [PubMed abstract]
23. Hollowell JG, Staehling NW, Hannon WH, Flanders DW, Gunter EW, Maberly GF, Braverman LE, Pino S, Miller DT, Garbe PL, DeLozier DM, Jackson RJ. Iodine nutrition in the United States. Trends and public health implications: iodine excretion data from National Health and Nutrition Examination Surveys I and IIIand 1988-1994). J Clin Endocrinol Metab. 1998 Oct;83(10):3401-3408. [PubMed abstract]
24. Pennington JA, Schoen SA. Total diet study: estimated dietary intakes of nutritional elements,Int J Vitam Nutr Res. 1996;66(4):350-362. [PubMed abstract]
25. Poulsen E. Case study: erythrosine. Food Addit Contam. 1993 May-Jun;10(3):315-323. [PubMed abstract]
26. Caldwell KL, Makhmudov A, Ely E, Jones RL, Wang RY. Iodine Status of the U.S.Population, National Health and Nutrition Examination Survey,andThyroid. 2011 Feb 16. [PubMed abstract]
27. Perrine CG, Herrick K, Serdula MK, Sullivan KM. Some subgroups of reproductive age women in the United States may be at risk for iodine deficiency. J Nutr. 2010 Aug;140(8):1489-1494. [PubMed abstract]
28. Pearce EN, Bazrafshan HR, He X, Pino S, Braverman LE. Dietary iodine in pregnant women from the Boston, Massachusetts area. Thyroid. 2004 Apr;14(4):327-328. [PubMed abstract]
29. Charlton KE, Gemming L, Yeatman H, Ma G. Suboptimal iodine status of Australian pregnant women reflects poor knowledge and practices related to iodine nutrition. Nutrition. 2010 Oct;26(10):963-8. [PubMed abstract]
30. Tayie FA, Jourdan K. Hypertension, dietary salt restriction, and iodine deficiency among adults. Am J Hypertens. 2010 Oct;23(10):1095-1102. [PubMed abstract]
31. International Council for the Control of Iodine Deficiency Disorders . Accessed 9/13/2010.
32. Santiago-Fernandez P, Torres-Barahona R, Muela-Martínez JA, Rojo-Martínez G, García-Fuentes E, Garriga MJ, León AG, Soriguer F. Intelligence quotient and iodine intake: a cross-sectional study in children. J Clin Endocrinol Metab. 2004 Aug;89(8):3851-3857. [PubMed abstract]
33. Vermiglio F, Lo Presti VP, Moleti M, Sidoti M, Tortorella G, Scaffidi G, Castagna MG, Mattina F, Violi MA, Crisà A, Artemisia A, Trimarchi F. Attention deficit and hyperactivity disorders in the offspring of mothers exposed to mild-moderate iodine deficiency: a possible novel iodine deficiency disorder in developed countries. J Clin Endocrinol Metab. 2004 Dec;89(12):6054-6060. [PubMed abstract]
34. Dal Maso L, Bosetti C, La Vecchia C, Franceschi S. Risk factors for thyroid cancer: an epidemiological review focused on nutritional factors. Cancer Causes Control. 2009 Feb;20(1):75-86. [PubMed abstract]
35. Cooper LF, Barber EM, Mitchell HS. Nutrition in Health and Disease, 9th ed. J.B. Lippincott Co, Philadelphia. 1943, pg 66.
36. Hess SY. The impact of common micronutrient deficiencies on iodine and thyroid metabolism: the evidence from human studies. Best Pract Res Clin Endocrinol Metab. 2010 Feb;24(1):117-132. [PubMed abstract]
37. UNICEF. The State of the World’s Children 2007, Statistics, Table 2: Nutrition . 2007.
38. Andersson M, de Benoist B, Rogers L. Epidemiology of iodine deficiency: Salt iodisation and iodine status. Best Pract Res Clin Endocrinol Metab. 2010 Feb;24(1):1-11. [PubMed abstract]
39. Melse-Boonstra A, Jaiswal N. Iodine deficiency in pregnancy, infancy and childhood and its consequences for brain development. Best Pract Res Clin Endocrinol Metab. 2010 Feb;24(1):29-38. [PubMed abstract]
40. Zimmermann MB. Iodine deficiency in pregnancy and the effects of maternal iodine supplementation on the offspring: a review. Am J Clin Nutr. 2009 Feb;89(2):668S-672S. [PubMed abstract]
41. Delange F. Iodine requirements during pregnancy, lactation and the neonatal period and indicators of optimal iodine nutrition. Public Health Nutr. 2007 Dec;10(12A):1571-1580. [PubMed abstract]
42. Hollowell JG, Haddow JE. The prevalence of iodine deficiency in women of reproductive age in the United States of America. Public Health Nutr. 2007 Dec;10(12A):1532-1539; discussion[PubMed abstract]
43. Velasco I, Carreira M, Santiago P, Muela JA, García-Fuentes E, Sánchez-Muñoz B, Garriga MJ, González-Fernández MC, Rodríguez A, Caballero FF, Machado A, González-Romero S, Anarte MT, Soriguer F. Effect of iodine prophylaxis during pregnancy on neurocognitive development of children during the first two years of life. J Clin Endocrinol Metab. 2009 Sep;94(9):3234-3241. [PubMed abstract]
44. Pearce EN, Leung AM, Blount BC, Bazrafshan HR, He X, Pino S, Valentin-Blasini L, Braverman LE. Breast milk iodine and perchlorate concentrations in lactating Boston-area women. J Clin Endocrinol Metab. 2007 May;92(5):1673-1677. [PubMed abstract]
45. Andersson M, Aeberli I, Wüst N, Piacenza AM, Bucher T, Henschen I, Haldimann M, Zimmermann MB. The Swiss Iodized Salt Program Provides Adequate Iodine for School Children and Pregnant Women, but Weaning Infants Not Receiving Iodine-Containing Complementary Foods as well as Their Mothers Are Iodine Deficient. J Clin Endocrinol Metab. 2010 Sep 1. [PubMed abstract]
46. Public Health Committee of the American Thyroid Association, Becker DV, Braverman LE, Delange F, Dunn JT, Franklyn JA, Hollowell JG, Lamm SH, Mitchell ML, Pearce E, Robbins J, Rovet JF. Iodine supplementation for pregnancy and lactation-United States and Canada: recommendations of the American Thyroid Association. Thyroid. 2006 Oct;16(10):949-951. [PubMed abstract]
47. Leung AM, Pearce EN, Braverman LE. Iodine content of prenatal multivitamins in the United States. N Engl J Med. 2009 Feb 26;360(9):939-940. [PubMed abstract]
48. Gregory CO, Serdula MK, Sullivan KM. Use of supplements with and without iodine in women of childbearing age in the United States. Thyroid. 2009 Sep;19(9):1019-1020. [PubMed abstract]
49. Rebagliato M, Murcia M, Espada M, Alvarez-Pedrerol M, Bolúmar F, Vioque J, Basterrechea M, Blarduni E, Ramón R, Guxens M, Foradada CM, Ballester F, Ibarluzea J, Sunyer J. Iodine intake and maternal thyroid function during pregnancy. Epidemiology. 2010 Jan;21(1):62-69. [PubMed abstract]
50. Pearce EN. What do we know about iodine supplementation in pregnancy? J Clin Endocrinol Metab. 2009 Sep;94(9):3188-3190. [PubMed abstract]
51. Angermayr L, Clar C. Iodine supplementation for preventing iodine deficiency disorders in children. Cochrane Database Syst Rev. 2004;(2):CD003819. [PubMed abstract]
52. Gordon RC, Rose MC, Skeaff SA, Gray AR, Morgan KM, Ruffman T. Iodine supplementation improves cognition in mildly iodine-deficient children. Am J Clin Nutr. 2009 Nov;90(5):1264-1271. [PubMed abstract]
53. Ghent WR, Eskin BA, Low DA, Hill LP. Iodine replacement in fibrocystic disease of the breast. Can J Surg. 1993 Oct;36(5):453-460. [PubMed abstract]
54. Azizi F, Smyth P. Breastfeeding and maternal and infant iodine nutrition. Clin Endocrinol (Oxf). 2009 May;70(5):803-809. [PubMed abstract]
55. Kessler JH. The effect of supraphysiologic levels of iodine on patients with cyclic mastalgia. Breast J. 2004 Jul-Aug;10(4):328-336. [PubMed abstract]
56. Center for Drug Evaluation and Research, Food and Drug Administration. Guidance. Potassium iodide as a thyroid blocking agent in radiation emergencies. December 2001.
57. World Health Organization. Guidelines for Iodine Prophylaxis following Nuclear Accidents . 1999.
58. Nauman J, Wolff J. Iodide prophylaxis in Poland after the Chernobyl reactor accident: benefits and risks. Am J Med. 1993;94:524-532. [PubMed abstract]
59. Pennington JA. A review of iodine toxicity reports. J Am Diet Assoc. 1990 Nov;90(11):1571-1581. [PubMed abstract]
60. Natural Medicines Comprehensive Database. Iodine. Accessed 10/13/2009.