• Journal of Nutrition and Health
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• 제55권2호
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• pp.250-262
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• 2022

Purpose: Elevated iodine intake is related to a higher prevalence of subclinical hypothyroidism (SCH). We investigated the short-term effect of dietary iodine restriction on thyroid function in patients with SCH with high iodine intakes. Methods: The iodine levels in 64 SCH patients with serum TSH levels from 4.0 to 10.0 mIU/L and normal serum fT4 levels (n = 64) were assessed using 24-hour urine iodine test results and iodine intake levels calculated using a semi-quantitative food frequency questionnaire. Dietary iodine restriction was not recommended for patients with an iodine intake in the normal range (group A, n = 13), but seaweed restriction was recommended for patients with high iodine intakes (group B, n = 33). Thyroid functions and iodine levels were rechecked after three months. Another eighteen patients were prescribed thyroid hormone replacement therapy according to clinical criteria. Results: Median baseline iodine intake for the 64 patients was 290.61 ㎍/day, and median 24-hour urine iodine was 33.65 µmol/g of creatinine. The major source of dietary iodine was seaweed, which accounted for 72.2% of median baseline intake. Urine iodine and calculated iodine intake levels were positively correlated with serum TSH levels (p < 0.001 and p = 0.027, respectively), and calculated iodine intakes were significantly correlated with urine iodine levels (p = 0.001). In group B, iodine restriction significantly decreased urine iodine (p = 0.042) and TSH levels (p = 0.004), and conversion to euthyroid status was achieved in 16 of the 33 patients (48.5%). Conclusion: Iodine intake and urine iodine levels are correlated with thyroid function in SCH patients, and dietary iodine restriction can aid functional thyroid recovery in patients with elevated iodine intakes.

• Journal of Nutrition and Health
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• 제30권10호
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• pp.1195-1202
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• 1997

Iodine-rich seaweed soup has been traditionally supplied to postpartum women in Korea. This dietary habit might introduce over-intake of iodine above the recommended requirements, and might provoke postpartum thyroid dysfunction. Although the response to excess iodine intake is highly variable, goiter, hyperthyroidism, hypothyroidism, and thyroiditis could follow the daily intake of 1,500$\mu\textrm{g}$ of iodine. A few studies are available concerning iodine toxicity in Korea. The purpose of this study was to investigate the relationships between the dietary intake of iodine and thyroid function change as well as the incidence of postpartum thyroiditis. One hundred and thirty-seven postpartum women who had experienced normal deliveries were studied. Dietary intake of iodine and excretion concentration of iodine in breast milk and maternal urine were measured . Serum T$_3$, T$_4$, TSH, anti-thyroglobulin antibody, and anti-microsomal antibody were anlayzed 1 week before delivery and 1, 6, 12, and24 weeks after delivery. Iodine intake was analyzed by one-to-one interviews using 24-hr recall and a food frequncy questionnaire. The result showed that the intake of dietary iodine before delivery and 1 and24 weeks after delivery were 483$\mu\textrm{g}$/day, 3367$\mu\textrm{g}$/day, and 1069$\mu\textrm{g}$/day, respectively. The concentration of iodine in urine at the first week after delivery was 63$\mu\textrm{g}$/dL, and 23.9$\mu\textrm{g}$/dL in breast milk . The levels of serum T$_3$ and T$_4$ before delivery were 2.01ng/mL and 11.49$\mu\textrm{g}$U/dL, respectively, showing that the levels were gradually dropping to normal values after delivery. Positive serum anti-thyroglobulin antibody and anti-microsomal antibody appeared in 3 cases. After a 24 week follow-up period , 6 women(10.3%) experienced cases of postpartum thyroiditis, 5 of which were cases of hyperthyroidism and one of which was a case of hypothyroidism. These figures of postpartum thyroiditis are similar to those of other countries.

• Journal of Nutrition and Health
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• 제27권10호
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• pp.1037-1047
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• 1994

Dietary iodine intake and urinary iodide excretion were meassured from 110 patients with various thyroid hormone diseses(hypothyroidism, hyperthyroidism, simple goiter and thyroid adenoma) and 67 normal control subjects. Iodine intake was assessed on the 24-hour recall dietary data using the compiled lists of food iodine values developed from various countries. Urinary iodide concentrations of drink water samples were measured with the iodide-selective electrode. The average iodine intake of the thyroid patients was 411$\mu\textrm{g}$, which was 87% higher(p<0.05) than that of the control subjects(220$\mu\textrm{g}$). Patients with hyperthyroidism and hypothyroidism or simple goiter excreted the most(0.6442ppm) amount of iodide respectively in the urine, with the control subject in the middle(0.5229ppm). Iodide concentrations of the drinking water samples were found to be in the range of 0.0015ppm to 0.0214ppm, which seemed to vary depending on the kind(underground water vs public water) and the location.

• Nutrition Research and Practice
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• 제10권2호
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• pp.167-174
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• 2016

BACKGROUND/OBJECTIVES: Despite the importance of a low-iodine diet (LID) for thyroid cancer patients preparing for radioactive iodine (RAI) therapy, few studies have evaluated dietary intake during LID. This study evaluated the amount of dietary iodine intake and its major food sources during a typical diet and during LID periods for thyroid cancer patients preparing for RAI therapy, and examined how the type of nutrition education of LID affects iodine intake. SUBJECTS/METHODS: A total of 92 differentiated thyroid cancer patients with total thyroidectomy were enrolled from Seoul National University Hospital. All subjects completed three days of dietary records during usual and low-iodine diets before $^{131}I$ administration. RESULTS: The median iodine intake was $290{\mu}g/day$ on the usual diet and $63.2{\mu}g/day$ on the LID. The major food groups during the usual diet were seaweed, salted vegetables, fish, milk, and dairy products and the consumption of these foods decreased significantly during LID. The mean energy intake on the LID was 1,325 kcal, which was 446 kcal lower than on the usual diet (1,771 kcal). By avoiding iodine, the intake of most other nutrients, including sodium, was significantly reduced during LID (P < 0.005). Regarding nutritional education, intensive education was more effective than a simple education at reducing iodine intake. CONCLUSION: Iodine intake for thyroid cancer patients was significantly reduced during LID and was within the recommended amount. However, the intake of most other nutrients and calories was also reduced. Future studies are needed to develop a practical dietary protocol for a LID in Korean patients.

• 대한지역사회영양학회지
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• 제26권1호
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• pp.48-55
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• 2021

Objectives: This study was conducted to estimate the dietary iodine intake of Koreans by a Total Diet Study (TDS) which provides 'closer-to-real' estimates of exposure to hazardous materials and nutrients through an analysis of table-ready (cooked) samples of foods. Methods: Dietary intake data from 2013-2017 Korea National Health and Nutrition Examination Survey (KNHANES) was used to select representative foods (RFs) for iodine analysis. A total of 115 RFs were selected and 158 'RF × cooking method-combination' pairs were derived by pairing each RF to corresponding cooking method(s) used more frequently. RFs were collected from 9 mega-markets in 9 metropolitan cities nationwide and mixed into composites prior to cooking preparation to a 'table ready' state for iodine analysis by inductively coupled plasma mass spectrometry. Iodine intake of Koreans was estimated based on the food intake data of the 2016-2018 KNHANES. Results: High iodine content was detected in seaweeds such as sea mustard and kelp. The mean iodine intake/capita/day was 418.4 ㎍ and the median value was 129.0 ㎍. Seaweeds contributed to 77.4% of the total iodine intake and the contribution by food item was as follows: sea mustard (44.0%), kelp (20.4%), laver (13.1%), milk (3.9%), egg (3.5%). Compared to the Dietary Reference Intakes for Koreans 2020, the proportion of people with iodine intake exceeding the tolerable upper intake level or below the estimated average requirement was high in the physiologically vulnerable groups (infants, children, pregnant women, and lactating women). Conclusions: The results, drawn from a TDS, are regarded closer to real estimates for iodine intake of Koreans compared with values in existing literature, which were based on a very limited variety of foods. On the other hand, it seems necessary to seek out solutions for the problematic iodine intake among physiologically vulnerable groups through in-depth analyses on food intake data collected with significant scale & quality.

• Journal of Nutrition and Health
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• 제45권3호
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• pp.218-228
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• 2012

The prevalence rate of thyroid dysfunction (hypothyroidism and hyperthyroidism) has increased within the Korean population and seems to be affected by iodine dietary habits. Some studies reported that the prevalence of thyroid dysfunction increase both in the area of iodine deficiency and excess. In this study, we tried to discover the difference in iodine intake, anthropometric measurements, and blood parameters between male subjects with or without subclinical thyroid dysfunction. A total of 5,249 subjects (Euthyroid: 4706, SubHypo: 454, SubHyper: 89) were used in this study. There were no significant differences in BMI, body fat, visceral fat, waist circumference, SBP, DBP, total cholesterol, HDL-cholesterol, LDL-cholesterol, TG, fasting serum glucose, HbA1c, alcohol intake, however significant differences were noticed in both age and smoking status. Through a food frequency questionnaire (FFQ), iodine intake per day was estimated. The average iodine intake was similar (SubHypo $392.9{\pm}279.0{\mu}g$, Euthyroid $376.5{\pm}281.7{\mu}g$, SubHyper $357.3{\pm}253.8 {\mu}g$) among groups. The main source of iodine intake was eggs (52.8%, 54.2%, 52.4%) followed by milk (16.3%, 15.8%, 17.8%), then sea mustard & sea tangle (12.4%, 11.9%, 11.6%). The prevalence of subclinical hypothyroidism and subclinical hyperthyroidism was higher in subjects whose intake was higher than the recommended nutrient intake (RNI). These results suggest that the excess consumption of iodine intake may act as one of the risk factors regarding thyroid dysfunction in Korea. Therefore, an adequate amount of iodine intake is necessary in order to prevent subclinical thyroid dysfunction and clinical thyroid dysfunction.

• Journal of Nutrition and Health
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• 제50권6호
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• pp.624-644
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• 2017

본 연구는 우리나라와 일본의 식품성분표를 함께 이용하여 한국인 상용식품의 요오드 데이터베이스를 구축하였고, 1998년~ 2014년의 국민건강영양조사 자료를 이용하여 한국 성인의 요오드 섭취량 및 추이를 분석하였다. 조사대상자는 19세 이상 성인을 대상으로 하여 총 56,818명이며, 대상자의 일반적 사항, 식생활 관련 요인, 식품군, 식사제공 장소 등으로 나누어 요오드 섭취량을 분석하였다. 전체 요오드 섭취량은 1998년에서 2014년으로 갈수록 감소하는 추세를 나타냈다. 일반적 사항에서 남녀의 비율은 50% 내외로 비슷한 수준이었으며, 여성보다 남성의 요오드 섭취량이 높게 나타났다. 연령의 경우, 30 ~ 49세의 요오드 섭취비율이 39 ~ 46%로 가장 높았다. 식생활 관련 요인은 점심에 요오드 섭취비율이 1998년에서 2014년까지 29.4 ~ 34.4% 사이로 가장 높았다. 음식 제공장소 중 가정식에서 섭취하는 요오드 섭취량은 시간이 지남에 따라 감소하는 것으로 나타났다. 식품군에 따른 요오드 섭취량은 해조류가 가장 높게 나타났으며 음식제공 형태별 요오드 섭취량은 모든 연도에서 국 및 탕류가 가장 높은 것으로 조사되었다. 요오드 주요 급원 식품으로는 다시마가 가장 요오드 함유량이 많은 식품으로 조사되었고 그 외 카레소스를 제외하고 미역, 김 등의 해조류가 상위권을 차지하였다. 연구결과를 종합해보면 한국 성인의 요오드 섭취량은 적정 수준으로 나타났다. 하지만 요오드 섭취량의 경우에는 상한 섭취량 기준이 있는 미량 영양소인 만큼 섭취에 대한 지속적인 관심이 필요할 것으로 보인다. 또한, 요오드 섭취량 변화에 따른 갑상선 질환을 비롯한 다른 요오드 관련 질환이나 요인들과의 관련성을 살펴보기 위한 후속 연구들에 있어서 기초자료로 도움이 되길를 기대해본다.

• Journal of Nutrition and Health
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• 제54권6호
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• pp.644-663
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• 2021

본 연구는 제6기 (2013-2015년) 국민건강영양조사 자료를 활용하여 만 15-45세의 가임기 여성 1,559명을 대상으로 요오드 섭취 및 소변 중 요오드 함량을 기준으로 요오드 섭취의 안전성을 평가하였다. 요오드 섭취량 분석을 위해 요오드 영양성분 DB를 구축한 후 24시간 식사조사자료와 매칭하여 식이를 통한 요오드 섭취량을 분석하였고, 소변 중 요오드 함량을 적용하여 하루 단위의 요오드 섭취량을 산출하였다. 또한 요오드 섭취의 안전성 평가를 위해 WHO의 평가기준을 적용하였고, 요오드의 영양소 섭취기준 중 상한섭취량을 기준으로 하여 BE를 산출한 후 소변 중 요오드 함량을 적용하여 HQ를 계산하였다. 그 결과 소변 중 요오드 함량이 100 ㎍/L 미만이어서 요오드 결핍으로 진단되는 비율은 15.22%이었고, 요오드 섭취 과잉으로 진단되는 300 ㎍/L 이상인 대상자는 48.16%이었다. 소변 중 요오드 함량은 평균 878.71 ㎍/L이었고, 요오드/크레아티닌은 589.00 ㎍/g이었으며, 요오드/크레아티닌은 30-45세 연령군이 15-18세, 19-29세 연령군에 비해 유의적으로 높았다. 식이를 통한 요오드 섭취량은 273.47 ㎍/day, 소변 중 요오드 함량을 통해 산출된 요오드 섭취량은 1,198.10 ㎍/day로, 두 조사방법에 의한 차이는 924.63 ㎍/day로 식이를 통한 요오드 섭취량보다 소변을 통해 산출된 요오드 섭취량이 더 높았다. 요오드 섭취량에 기여도가 높은 식품은 채소류, 어패류, 해조류 및 가공식품이었고, 요오드 섭취의 위험도를 평가하는 HQ는 한국인 영양소섭취기준 적용 시 0.228이었고, 소변 중 요오드 함량이 1,000 ㎍/L 이상 시 평균 1.665로 1 이상의 높은 수준이었다. 혈중 TSH는 2.14 mIU/L, free T4는 1.10 ng/L이었으며, 소변 중 요오드 수준과 HQ는 혈중 TSH 농도에 유의적인 차이를 보이지 않았으나, 혈중 free T4 농도는 연령과 소변 중 요오드 수준이 증가할수록 유의적으로 감소하였다. 본 연구결과 국내 가임기 여성의 과반수는 요오드를 과잉 섭취하였고, 특히 상위 10% 정도는 HQ 1 이상으로 건강에 위험할 정도의 극단적인 섭취량을 보였다, 또한, 식이와 소변을 통해 산출된 요오드 섭취량 사이에 차이가 상당히 큰 것으로 보아 충분한 요오드 DB가 구축되지 않은 현 상황에서 식이를 통한 요오드 영양상태를 평가하기보다는 소변으로 배출된 요오드 함량을 적용하여 요오드 영양상태를 평가하는 것이 더 적절할 것으로 사료되며, 과잉의 요오드 섭취가 갑상샘질환 뿐만이 아니라 관련 질환의 유병율에 미치는 다양한 연구가 수행될 필요가 있을 것으로 판단된다.

• Journal of Nutrition and Health
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• 제53권3호
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• pp.271-287
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• 2020

본 연구는 한국인의 상용 식품에 대한 요오드 데이터베이스를 개정하고, 버전을 달리하여 한국인의 요오드 섭취수준을 평가하였으며, 배설량을 이용하여 섭취량과의 상관성을 살펴보았다. 요오드 데이터베이스는 기존의 Han 등 [2]의 데이터베이스를 기초로 최신의 참고문헌들을 활용하여 개정하였다. 요오드 데이터베이스 구축은 상용 식품 목록에 분석값, 문헌값, 대체값, 결측값 등의 우선순위 순서로 요오드값을 적용하였고, 분석값은 총 166개 (19.4%), 문헌값 318개 (37.2%), 대체값 총 247개 (28.9%), 결측값 124개 (14.5%)이었다. 대체값은 레시피나 수분함량을 고려하여 계산하거나 유사식품들의 일반값을 생성하여 사용하였고, 일반값 생성 시 평균값과 최솟값을 선정하여 버전 1과 2로 구분하였다. 한국 성인의 요오드 섭취 수준 평가는 제6기 국건영을 활용하였고, 요오드 섭취량의 중앙값은 전체의 경우 352.1 ㎍/일이었고 남자는 400.8 ㎍/일이며, 여자는 389.0 ㎍/일이었다. 이는 버전 2과 비교하여 조금 높았지만 큰 차이는 보이지 않았다. 전체 요오드 섭취량에 대한 식품군별 기여도의 경우 해조류 55.7%, 절임 채소류 16.0%, 우유 및 유제품류 6.9%이었고 버전 2에서도 순서는 동일하였다. 해조류 섭취 여부에 따라 해조류 섭취군과 미섭취군으로 나누어 평가한 결과, 해조류 섭취군의 요오드 섭취량의 중앙값은 495.7 ㎍으로 미섭취군의 241.2 ㎍보다 약 2배 이상 높았다. 해조류의 분석값 차이에 따른 요오드 섭취량의 차이를 살펴보기 위해 세부 버전을 사용하였고, 버전 1_1을 이용하였을 때의 요오드 섭취량의 중앙값은 478.1 ㎍으로 버전 1의 요오드 섭취량의 중앙값은 495.7 ㎍에 비해 낮았다. 요오드 섭취수준 평가는 해조류 미섭취군에서는 평균 필요량 (95 ㎍/일) 미만으로 섭취하는 비율이 남자 8.8%, 여자 8.1%로 높게 나왔고, 해조류 섭취군에서는 상한섭취량 (2,400 ㎍/일) 초과하여 섭취하는 비율이 남자 8.0%, 여자 6.3%로 높게 나타났다. 요오드 섭취량과 배설량 간의 상관성을 소변 요오드 배설량과 소변 속 크레아티닌의 비율을 이용하였고 섭취량과의 회귀계수는 버전 1은 0.11718, 버전 2는 0.11512이었고 모두 유의적 상관성을 나타내었다 (p < 0.0001). 이상의 결과에서 요오드 데이터베이스를 개정하고 데이터베이스 버전에 따라 한국의 요오드 섭취수준을 파악하였고, 해조류 섭취가 한국인의 주요한 급원 식품이었으며, 해조류 섭취 시 요오드 섭취의 과잉이, 해조류 미섭취 시 요오드 섭취의 부족이 나타날 수 있음을 제시하였다. 본 연구는 향후 요오드 데이터베이스의 지속적인 개정과 관리에 기초자료가 될 것으로 사료되고, 해조류 섭취 유무에 따른 요오드 섭취의 교육자료나 영양 프로그램 자료에 활용될 수 있을 것이며, 요오드 섭취와 연관성이 높은 갑상선 관련 질환과의 연구에도 활용될 수 있을 것으로 생각된다.

• Asian-Australasian Journal of Animal Sciences
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• 제14권6호
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• pp.785-790
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• 2001

Twelve indigenous male goats, comprising of six intact and six castrated (2.5-3 years; $24.4{\pm}0.62kg$) were assigned evenly into two dietary treatments, viz. $I_0$ and $I_{100}$ and were used to study the effect of supplementation of iodine on the nutrient utilization when their diet contained Leucaena leaf meal. They were offered a conventional concentrate mixture along with Leucaena leucocephala leaf meal, the latter to meet 50% of their crude protein (CP) requirements, and supplemented with either no iodine ($I_0$) or 0.1 mg of iodine ($I_{100}$)/day/animal as potassium iodide for a period of 105 days. Wheat straw given ad libitum was the sole source of roughage. A metabolism trial of 8 days duration was conducted after 90 days of experimental feeding. It was observed that the overall dry matter (DM) intake during experimental period was higher (p<0.05) in $I_{100}$ group as compared to $I_0$ group (508.6 vs. $443.7g\;d^{-1}$). The intake of CP, digestible crude protein (DCP) and metabolisable energy (ME), although non-significant, tended to be higher in the iodine supplemented group, $I_{100}$. Digestibility of dry matter, organic matter (OM), CP, ether extract and crude fiber (CF) did not differ (p>0.05) between the treatments. However, nitrogen retention was higher (p<0.01) in $I_{100}$ than $I_0$ with the values being 2.63 and $1.70g\;d^{-1}$, respectively. No difference (p>0.05) was evident in the retention of calcium and phosphorus between the two groups. The castrated animal exhibited lower DM intake concurrent with higher digestibility of DM and crude fibre (p<0.05), and organic matter and total carbohydrates (p<0.01) when compared to intact ones. It was concluded that supplementation of iodine to leucaena based ration may help in improving the DM intake and nitrogen utilization by goats.