Goiter

Also indexed as: Iodine Deficiency Hypothyroidism

Goiter is an enlargement of the thyroid gland that often produces a noticeable swelling in the front of the neck. This enlargement can be caused by iodine deficiency, inability of the body to use iodine correctly, or a variety of thyroid disorders, including infection, tumors, and autoimmune disease. Some environmental pollutants, heavy metal poisonings, and certain drugs can also contribute to goiter formation.1 2 3 Both iodine deficiency and inability to use iodine properly make the thyroid gland unable to produce thyroid hormone, a hormone that helps to regulate the body’s metabolic rate. This state is called hypothyroidism and the symptoms include fatigue, weight gain, heavy menstrual bleeding in women, dry skin and hair, as well as goiter.

Iodine-deficiency goiter can be common in regions where the soils and foods have insufficient iodine. Preschool children, adolescent girls, pregnant women, and the elderly are most vulnerable to goiter and other iodine-deficiency disorders.4 Areas where iodine supplies are inadequate see high rates not only of goiter but also of birth defects and retardation of both mental and physical development.5 While iodine deficiency is the leading cause of goiter worldwide, it is a rare cause of goiter in the developed world. For this reason, any goiter that occurs in the developed world must be evaluated by a healthcare provider and its cause determined before any treatment is given.

Checklist for Goiter

Rating Nutritional Supplements Herbs
3Stars Iodine  
1Star Manganese (if deficient)
Vitamin A
Vitamin E
Zinc (if deficient)		  
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

What are the symptoms of goiter? People with goiter may notice a soft swelling in the front of the neck.

How is it treated? Conventional treatment includes the use of iodized table salt and the avoidance of goitrogenic (goiter promoting) foods (e.g., cabbage, Brussels sprouts, and soy). Doctors may also recommend suppression of the thyroid with oral thyroid medication such as L-thyroxine (Synthroid®). For cosmetic reasons or in cases of large goiters that interfere with breathing or swallowing, doctors may recommend surgical removal or radioactive iodine treatments to reduce the goiter.

Dietary changes that may be helpful: The most important dietary concern in treating iodine-deficiency hypothyroidism and preventing goiter is ensuring adequate intake of iodine. Iodine is found naturally in foods from the ocean, such as seafood, kelp, and other sea vegetables, and in plant and animal products produced in areas where soil and water contain sufficient iodine.6 7 In developed countries, commercial table salt has been fortified with iodine since the 1920s to prevent deficiency.8 Iodized salt contains approximately 100 micrograms of iodine per gram of salt. This fortified salt is used directly and is incorporated into animal feeds and processed foods making it easy to achieve the Recommended Dietary Allowance (RDA) of 150 mcg for adolescents and adults and 200 mcg daily for pregnant and breast-feeding women.9 Iodized salt has proven so effective it is recommended as the intervention of choice to eliminate iodine deficiency worldwide.10 11 Iodized oils, given as an annual injection or as food by mouth, have also been used effectively to treat iodine-deficiency goiter.12 13

Although iodine deficiency and goiter are now quite uncommon in developed countries, recent studies have found that the average dietary iodine intake in the United States has fallen below RDA guidelines.14 Long-term excessive dietary intake of iodine (1,000 to 2,000 micrograms daily), while less common than iodine deficiency, can occur in people who eat large amounts of kelp and other sea vegetables and can also cause goiter.15 16

A number of commonly eaten foods have been shown to interfere with the use of iodine by the thyroid, thus reducing production of thyroid hormone and causing goiter. These foods, known as goitrogens, include vegetables in the Brassica family such as broccoli, cabbage, kale and mustard,17 millet,18 soybeans,19 pine nuts20 and some seed meals used in animal feeds.21 22 These foods can be safely eaten in moderate amounts by people who consume adequate iodine.23 A combination of low iodine intake and high intake of goitrogenic foods increases the likelihood of goiter.24 25

Nutrient deficiencies, including zinc,26 manganese 27 and vitamin A,28 29 and severe protein malnutrition30 also contribute to an inability to use iodine well and to the development of goiter.31 32 In the presence of adequate iodine supplies, it is less common for such factors to cause goiter;33 34 however, when iodine intake becomes deficient, even mild malnutrition can have such a negative impact on thyroid function.35 36 High levels of minerals such as calcium and magnesium, and certain bacteria in drinking water, have also been shown to be goitrogenic.37 38 Therefore, proper nutrition and a healthy water supply are crucial in the prevention and treatment of goiter.

Nutritional supplements that may be helpful: Iodine supplementation can be an effective treatment of iodine deficiency hypothyroidism and can halt the growth of goiter if the cause is not complicated by malnutrition or environmental and dietary goitrogens.39 40 Iodine supplements will help to shrink goiters during early stages, but they have no effect in later stages.41 Ingestion of 2,000 to 6,000 mcg of iodine daily over long periods of time can be toxic to the thyroid and can be a cause of goiter.42 43

Blood levels of vitamin A are lower in people with goiter than in similar people without goiter.44 45 The same relationship has been found for vitamin E and goiter.46 Animal research has found that, in iodine-deficient conditions, a supplement combination of vitamin C, vitamin E, and beta-carotene prevented goiter formation (though hypothyroidism was not improved), and vitamin E alone had a similar effect.47 No studies have been done to investigate this benefit in humans.

When iodine deficiency is present, other nutrient levels become important in the development of goiter. Deficiencies of zinc 48 and manganese 49 can both contribute to iodine-deficiency goiter; however, an animal study found that manganese excess can also be goitrogenic.50 It has been suggested that selenium deficiency may contribute to goiter.51 However, when selenium supplements were given to people deficient in both iodine and selenium, thyroid dysfunction was aggravated, and it has been suggested that selenium deficiency may provide some protection when there is iodine deficiency.52 53 A study of the effects of selenium supplementation at 100 mcg daily in women without selenium deficiency but with slightly low iodine intake found no effect on thyroid function.54 The authors concluded that selenium supplementation seems to be safe in people with only iodine deficiency but not in people with combined selenium and iodine deficiencies. In those cases, iodine supplementation has been shown to be most useful.55 No studies have been done to evaluate the usefulness of supplementation with zinc or manganese to prevent or treat goiter.

Are there any side effects or interactions? Refer to the individual supplement for information about any side effects or interactions.

References:

1. Prescott E, Netterstrom B, Faber J, et al. Effect of occupational exposure to cobalt blue dyes on the thyroid volume and function of female plate painters. Scand J Work Environ Health 1992;18:101–4.

2. Gaitan E. Goitrogens. Baillieres Clin Endocrinol Metab 1988;2:683–702 [review].

3. Gaitan E. Goitrogens in food and water. Annu Rev Nutr 1990;10:21–39 [review].

4. Ingenbleek Y, De Visscher M. Hormonal and nutritional status: critical conditions for endemic goiter epidemiology? Metabolism 1979;28:9–19 [review].

5. Lamberg BA. Endemic goitre—iodine deficiency disorders. Ann Med 1991;23:367–72 [review].

6. Lamberg BA. Iodine deficiency disorders and endemic goitre. Eur J Clin Nutr 1993;47:1–8 [review].

7. Koutras DA. Iodine metabolism in endemic goitre. Ann Clin Res 1972;4:55–63 [review].

8. Lee K, Bradley R, Dwyer J, Lee S. Too much versus too little: The implications of current iodine intake in the United States. Nutr Rev 1999;57:177–81 [review].

9. Lee K, Bradley R, Dwyer J, Lee S. Too much versus too little: The implications of current iodine intake in the United States. Nutr Rev 1999;57:177–81 [review].

10. Lamberg BA. Endemic goitre—iodine deficiency disorders. Ann Med 1991;23:367–72 [review].

11. Dunn JT. Seven deadly sins in confronting endemic iodine deficiency, and how to avoid them. J Clin Endocrinol Metab 1996;81:1332–5 [review].

12. Ingenbleek Y, Jung L, Ferard G. Brassiodol, a new iodised oil for goitrous patients. Coll Antropol 1998;22:51–62.

13. Untoro J, Schultink W, Gross R, et al. Efficacy of different types of iodised oil. Lancet 1998;351:752–3.

14. Lee K, Bradley R, Dwyer J, Lee S. Too much versus too little: The implications of current iodine intake in the United States. Nutr Rev 1999;57:177–81 [review].

15. Franceschi S, Talamini R, Fassina A, Bidoli E. Diet and epithelial cancer of the thyroid gland. Tumori 1990;76:331–8 [review].

16. Wilson JD, Foster DW, Kronenberg HM, Larsen PR. Williams Textbook of Endocrinology, 9th edition. Philadelphia: WB Saunders Co, 1998, 469.

17. Stoewsand GS. Bioactive organosulfur phytochemicals in Brassica oleracea vegetables—a review. Food Chem Toxicol 1995;33:537–43 [review].

18. Sartelet H, Serghat S, Lobstein A, et al. Flavonoids extracted from fonio millet (Digitaria exilis) reveal potent antithyroid properties. Nutrition 1996;12:100–6.

19. Divi RL, Chang HC, Doerge DR. Anti-thyroid isoflavones from soybean: isolation, characterization and mechanisms of action. Biochem Pharmacol 1997;54:1087–96.

20. Gaitan E. Goitrogens in food and water. Annu Rev Nutr 1990;10:21–39 [review].

21. Mawson R, Heaney RK, Zdunczyk Z, Kozlowska H. Rapeseed meal-glucosinolates and their antinutritional effects. Part 4. Goitrogenicity and internal organs abnormalities in animals. Nahrung 1994;38:178–91.

22. Bell JM. Nutrients and toxicants in rapeseed meal: a review. J Anim Sci 1984;58:996–1010 [review].

23. Gaitan E. Goitrogens. Baillieres Clin Endocrinol Metab 1988;2:683–702 [review].

24. Gaitan E. Goitrogens. Baillieres Clin Endocrinol Metab 1988;2:683–702 [review].

25. Gaitan E. Goitrogens in food and water. Annu Rev Nutr 1990;10:21–39 [review].

26. Ozata M, Salk M, Aydin A, et al. Iodine and zinc, but not selenium and copper, deficiency exists in a male Turkish population with endemic goiter. Biol Trace Elem Res 1999;69:211–6.

27. Kawada J, Nishida M, Yoshimura Y, Yamashita K. Manganese ion as a goitrogen in the female mouse. Endocrinol Jpn 1985;32:635–43.

28. Ingenbleek Y, Luypaert B, De Nayer P. Nutritional status and endemic goitre. Lancet 1980;1:388–91.

29. Osman AK, Fatah AA. Factors other than iodine deficiency contributing to the endemicity of goitre in Darfur Province (Sudan). J Hum Nutr 1981;35:302–9.

30. Ingenbleek Y, Luypaert B, De Nayer P. Nutritional status and endemic goitre. Lancet 1980;1:388–91.

31. Osman AK, Fatah AA. Factors other than iodine deficiency contributing to the endemicity of goitre in Darfur Province (Sudan). J Hum Nutr 1981;35:302–9.

32. Gaur DR, Sood AK, Gupta VP. Goitre in school girls of the Mewat area of Haryana. Indian Pediatr 1989;26:223–7.

33. Gaitan E. Goitrogens. Baillieres Clin Endocrinol Metab 1988;2:683–702 [review].

34. Lamberg BA. Endemic goitre--iodine deficiency disorders. Ann Med 1991;23:367–72 [review].

35. Centanni M, Maiani G, Vermiglio F, et al. Combined impairment of nutritional parameters and thyroid homeostasis in mildly iodine-deficient children. Thyroid 1998;8:155–9.

36. Filteau SM, Sullivan KR, Anwar US, et al. Iodine deficiency alone cannot account for goitre prevalence among pregnant women in Modhupur, Bangladesh. Eur J Clin Nutr 1994;48:293–302.

37. Gaur DR, Sood AK, Gupta VP. Goiter in school children of the Mewat area of Haryana. Indian Pediatr 1989;26:223–7.

38. Gaitan E. Goitrogens in food and water. Annu Rev Nutr 1990;10:21–39 [review].

39. Koutras DA. Iodine metabolism in endemic goitre. Ann Clin Res 1972;4:55–63 [review].

40. Lee K, Bradley R, Dwyer J, Lee S. Too much versus too little: The implications of current iodine intake in the United States. Nutr Rev 1999;57:177–81 [review].

41. Cotran RS, Kumar V, Robbins SL. Robbins Pathologic Basis of Disease, 4th edition. Philadelphia: WB Saunders Co, 1989, 1227–8.

42. Gaitan E. Goitrogens in food and water. Annu Rev Nutr 1990;10:21–39 [review].

43. Wilson JD, Foster DW, Kronenberg HM, Larsen PR. Williams Textbook of Endocrinology, 9th edition. Philadelphia: WB Saunders Co, 1998, 469.

44. Keyvani F, Yassai M, Kimiagar M. Vitamin A status and endemic goiter. Int J Vitam Nutr Res 1988;58:155–60.

45. Mesaros-Kanjski E, Kontosic I, Kusic Z, et al. Endemic goitre and plasmatic levels of vitamins A and E in the school-children on the island of Krk, Croatia. Coll Antropol 1999;23:729–36.

46. Mesaros-Kanjski E, Kontosic I, Kusic Z, et al. Endemic goitre and plasmatic levels of vitamins A and E in the school-children on the island of Krk, Croatia. Coll Antropol 1999;23:729–36.

47. Mutaku JF, Many MC, Colin I, et al. Antigoitrogenic effect of combined supplementation with dl-alpha-tocopherol, ascorbic acid and beta-carotene and of dl-alpha-tocopherol alone in the rat. J Endocrinol 1998;156:551–61.

48. Ozata M, Salk M, Aydin A, et al. Iodine and zinc, but not selenium and copper, deficiency exists in a male Turkish population with endemic goiter. Biol Trace Elem Res 1999;69:211–6.

49. Kawada J, Nishida M, Yoshimura Y, Yamashita K. Manganese ion as a goitrogen in the female mouse. Endocrinol Jpn 1985;32:635–43.

50. Kawada J, Nishida M, Yoshimura Y, Yamashita K. Manganese ion as a goitrogen in the female mouse. Endocrinol Jpn 1985;32:635–43.

51. Untoro J, Ruz M, Gross R. Low environmental selenium availability as an additional determinant for goiter in East Java, Indonesia? Biol Trace Elem Res 1999;70:127–36.

52. Corvilain B, Contempre B, Longombe AO, et al. Selenium and the thyroid: how the relationship was established. Am J Clin Nutr 1993;57:244S–248S [review].

53. Vanderpas JB, Contempre B, Duale NL, et al. Selenium deficiency mitigates hypothyroxinemia in iodine-deficient subjects. Am J Clin Nutr 1993 Feb;57(2 Suppl):271S–275S [review].

54. Roti E, Minelli R, Gardini E, et al. Selenium administration does not cause thyroid insufficiency in subjects with mild iodine deficiency and sufficient selenium intake. J Endocrinol Invest 1993;7:481–4.

55. Zimmermann MB, Adou P, Torresani T, et al. Effect of oral iodized oil on thyroid size and thyroid hormone metabolism in children with concurrent selenium and iodine deficiency. Eur J Clin Nutr 2000;3:209–13.