Nationwide Representative Survey of Dietary Iodine Intake and Urinary Excretion in Postpartum Korean Women

Iodine is an essential component of thyroid hormones, but excessive iodine intake can lead to thyroid dysfunction. Traditionally, Korean mothers consume brown seaweed soup (miyeokguk), a high source of iodine, after childbirth. There is controversy regarding the effects of excessive postpartum iodine intake on the health of mothers and infants. Thus far, there have been no nationwide large-scale surveys regarding the status of iodine intake among postpartum women in Korea. Therefore, we conducted a nationwide survey of postpartum dietary iodine intake among Korean women. In total, 1054 Korean women aged ≥19 years, at less than 8 weeks postpartum, participated in this survey. Dietary data were collected using self-reported 2-day dietary records, along with before-and-after meal photos. To evaluate the correlation between dietary iodine and urinary iodine excretion (UIE), spot urine, and 24 h urine samples were collected from 98 and 29 participants, respectively. The mean daily iodine intake among all participants was 2945.6 μg, and it gradually decreased over time after childbirth. Dietary iodine intake was significantly correlated with 24 h UIE (r = 0.396, p < 0.05) and spot urine UIE (r = 0.312, p < 0.05). Follow-up studies are required to examine the influence of excessive postpartum iodine intake on thyroid health in mothers and their infants.     

Dietary selenium intake and selenium concentrations of plasma, erythrocytes, and breast milk in pregnant and postpartum lactating and nonlactating women

The selenium status of a group of 23 lactating and 13 nonlactating women was assessed from 37-wk gestation through 6-mo postpartum. The mean overall dietary Se intake of both groups of women was 80 +/- 37 micrograms/d. Plasma and erythrocyte Se levels were lower in the lactating than in the nonlactating mothers both before and after parturition. Breast-milk Se concentrations fell from 20 micrograms/L (0.25 mumol/L) at 1-mo postpartum to 15 micrograms/L (0.19 mumol/L) at 3- and 6-mo postpartum. A weak (r = 0.38) but statistically significant (p less than 0.025) relationship was observed between maternal plasma Se level and breast-milk Se concentration. The dietary Se intake of these lactating North American women appears sufficient to maintain satisfactory Se nutriture in their breast-fed infants during the first 6 mo of lactation.     

Longitudinal study on the dietary selenium intake of exclusively breast-fed infants and their mothers in Finland

The dietary selenium intakes of a group of 13 lactating women living in the Helsinki metropolitan area and those of their 10 exclusively breast-fed infants were studied twice during the course of lactation. The first survey period of the women ranged from 6 to 8 weeks post-partum and the second from 17 to 22 weeks post-partum. The selenium intakes of the infants were determined at 1 and 3 months post-partum. In addition, the concentrations of selenium in the breast milk of four of the mothers were determined 6 months post-partum. Milk samples were collected by a method eliminating errors due to diurnal variations and variations during a single feeding. The validity of the analytical method employed was confirmed by means of an interlaboratory collaboration. The level of selenium concentration in the breast milk fell significantly (P less than 0.0005) from 10.7 +/- 1.6 micrograms/l at 1 month of lactation to 5.8 +/- 1.2 micrograms/l at 3 months of lactation, but remained at that level for up to 6 months of lactation (5.6 +/- 0.4 micrograms/l). The total dietary selenium intake of the infants fell significantly (P less than 0.0005) from 8.0 +/- 1.8 micrograms/d to 4.7 +/- 1.1 micrograms/d at 1 and 3 months post-partum, respectively. The mean maternal dietary selenium intake was 36 +/- 13 micrograms/d during the first survey period and 30 +/- 12 micrograms/d during the second survey period.(ABSTRACT TRUNCATED AT 250 WORDS)     

A randomized trial of supplementation with docosahexaenoic acid-rich tuna oil and its effects on the human milk cytokines interleukin 1 beta, interleukin 6, and tumor necrosis factor alpha

BACKGROUND: Increased consumption of n-3 long-chain polyunsaturated fatty acids (PUFAs) has been recommended during pregnancy and lactation. The production of proinflammatory cytokines by human peripheral blood mononuclear cells (PBMCs) can be modified by dietary n-3 PUFAs. OBJECTIVE: We sought to determine whether dietary supplementation of lactating women with docosahexaenoic acid (DHA) can modulate the concentration of cytokines in the aqueous phase of human milk and the production of cytokines by human milk cells (HMCs) and PBMCs. DESIGN: In this double-blind, prospective, randomized trial, mothers of healthy full-term infants were asked to consume daily a nutritional supplement of 2000 mg oil containing either placebo (n = 40), 300 mg DHA + 70 mg eicosapentaenoic acid (EPA; n = 40), or 600 mg DHA + 140 mg EPA (n = 40). The fatty acid composition of plasma, PBMCs, milk, and HMCs from lactating mothers at 4 wk postpartum was measured by gas chromatography. The concentration of interleukin 6 and tumor necrosis factor alpha in milk and the production of interleukin 1beta, tumor necrosis factor alpha, and interleukin 6 by PBMCs and HMCs after stimulation with lipopolysaccharide was measured by enzyme-linked immunosorbent assay. RESULTS: At 4 wk postpartum, 82 mothers were still breast-feeding their infants. DHA increases in maternal plasma, PBMCs, milk, and HMCs were proportional to dietary DHA. There was no relation between tissue DHA status and cytokine concentrations. CONCLUSIONS: Consumption of < or = 600 mg DHA and 140 mg EPA/d for 4 wk increased n-3 PUFA concentrations in relevant tissues but did not cause perturbations in cytokine concentrations in human milk.     

Iodine intake of Japanese male university students: urinary iodine excretion of sedentary and physically active students and sweat iodine excretion during exercise

We examined the urinary iodine excretion of sedentary and physically active male university students in order to estimate the iodine intake of Japanese. Iodine excretion in sweat collected during treadmill exercise was also determined in different dietary iodine levels. The mean urinary iodine excretion of 5 sedentary students during 15 consecutive days was 357 micrograms/day (40-3,390). When high-iodine food, i.e. seaweed, was included in meals in only 22% of the total experimental days of 5 subjects, the urinary iodine excretion was high (1,106 micrograms/day, 298-3,390), but was low (153 micrograms/day, 40-441) when seaweeds were not consumed. An unexpectedly low mean urinary iodine excretion of 149 micrograms/day (50-393) was found in 10 rowing club students during 6 consecutive days of their summer training camp, probably being due to iodine losses in sweat; sweat iodine concentrations were about 37 micrograms per liter, regardless of serum and urinary iodine levels modulated by the dietary iodine level. The present data indicate that the iodine intake of Japanese depends on the amount of seaweed consumption and that it is not necessarily as high as expected from the data obtained in the 1960s. Moreover, our findings indicate the importance of taking account of iodine loss in sweat in the evaluation of iodine nutrition for physically active persons working in hot and humid environments.     

Effect of thiocyanate levels in milk on thyroid function in iodine deficient subjects

To utilize the antibacterial effect of the lactoperoxidase system to prevent bacterial spoilage of raw milk it is necessary to increase the thiocyanate concentration of the milk. Thiocyanate has, however, a potent antithyroid effect which is enhanced by iodine deficiency. In this study the thyroid function has been studied, before and after 4 weeks daily administration of 250 ml of such treated milk, in 55 goitrous subjects living in an endemic goiter region of western Sudan. The iodine content was 0.1 mg/l and the thiocyanate content was either 3.6 mg/l (n 19) or 19 mg/l (n 36) in the milk. At the start of the experiment all subjects were iodine deficient with a urinary excretion of 40-50 micrograms/g creatinine. After 4 weeks daily intake of 4.75 mg of thiocyanate by way of milk the serum thiocyanate level increased by approximately 1.7 mg/l. Both at the beginning and at the end of the experimental period the serum levels of thyroxine, triiodothyronine and TSH were in the normal range for all subjects. After 4 weeks the TSH levels had decreased significantly, (from 2.6 +/- 0.2 to 2.1 +/- 0.2 mU/l, p less than 0.001) probably as an effect of the supplementary intake of iodine. The thyroid hormone levels remained unchanged during the experimental period. In conclusion, the intake of milk with an iodine concentration of 0.1 mg/l and a thiocyanate concentration of 19 mg/l does not have a negative effect on the thyroid function in iodine deficient subjects.     

不同地区乳汁中锌、铜、铁含量的研究

本研究收集了我国７个不同地区共１０１２份产后１～６个月乳母的乳汁进行了锌、铜、铁含量测定，结果均以产后１２天较高，其平均含量分别为４．５２±１．７０，０．５１±０．１６和１．０３±０．５３μｇ／ｇ，并随泌乳期延长而下降。不同地区乳汁中锌、铜、铁含量存在一定差异。各地区乳汁中锌含量均与乳母膳食中动物性来源锌及动物性蛋白质摄取量呈正相关。乳汁中铜含量与乳母膳食中动物性蛋白质摄取量也呈正相关。未发现乳汁中铁含量与乳母膳食中营养素的摄取量有关。     

兰州市城区102例乳母膳食营养状况及其与乳汁成分关系

目的 了解兰州市城区乳母膳食营养状况及其与乳汁成分的关系。方法 招募102位乳母,通过问卷调查其基本情况和膳食状况,计算膳食营养素摄入量,采集血液样本检测血红蛋白和微量元素水平,采集母乳分析体质指数及宏量营养素摄入和乳汁成分的关系。结果 乳母能量摄入量中位数为1 507.5（1 245.5,1 954.5）kcal,能量和宏量营养素及多种微量营养素摄入量均不足,蛋白质、脂肪和碳水化合物供能比分别为13.72%、25.67%、60.90%;乳汁中脂肪、总蛋白质、糖类、干物质、能量的含量分别为（4.33±1.23）g/100 mL、（1.23±0.24）g/100 mL、（7.07±0.32）g/100 mL、（12.82±1.13）g/100 mL、（73.70±10.93）kcal/100 mL。不同BMI分组乳母乳汁中脂肪、干物质以及能量含量不同（均P<0.05）,超重/肥胖组乳母乳汁中能量、脂肪以及干物质含量高。乳汁成分和乳母膳食宏量营养素之间未发现相关性（均P>0.05）。乳母血红蛋白平均含量为（137.23±1.10）g/L,7例（7.53%）贫血,乳母缺乏的微量元素主要为镁（24.73%）和铁（7.53%）。结论 需要加强对乳母的营养宣教,鼓励其合理膳食,定期检测血红蛋白浓度,及时发现健康问题并改善。     

Copper, iron, zinc, and selenium dietary intake and status of Nepalese lactating women and their breast-fed infants

The dietary intake of copper, iron, zinc, and selenium of 26 Nepalese lactating mothers was estimated from chemical analysis of 24-h food and beverage composites. Fasting blood and milk samples were obtained from the mothers and blood samples were obtained from the infants. The Nepalese mothers consumed significantly more Cu, significantly less Fe and Se, and similar amounts of Zn as compared with American lactating women. Blood Fe status indices and plasma concentrations of Cu, Zn, and Se were lower in the Nepalese mothers than in the American mothers. These lower values may in part be related to the high neutral detergent fiber and phytate content of the Nepalese diet, which could make these minerals less available for absorption. The high exposure to infections in Nepal may also depress Fe status indices and plasma Zn concentrations. The lower dietary Se intake of the Nepalese mothers was reflected in lower milk concentrations.     

Studies of the relation between the nutritional status of lactating mothers and milk composition as well as the milk intake and growth of their infants in Beijing. Pt. 4. The protein and amino acid content of breast milk]

Breastmilk from lactating women in urban, suburban, and rural areas of Beijing and in the village of Jiangxi province was collected at 106 months postpartum and analyzed for total nitrogen and 18 amino acids. The protein intake of Jiangxi mothers was much lower than that of mothers in the 3 areas of Beijing. The total nitrogen content of milk among the former showed significantly lower values, but there were no significant differences in the total amount of 18 amino acids in milk among the 4 groups. The true protein contents of mature milk in the 4 groups, as determined by amino acid analysis, were 0.98, 1.04, 1.01, and 0.96%, respectively. These were lower than the values calculated from total nitrogen determination. The high nonprotein nitrogen in human milk led to overestimate the protein content of breastmilk by the latter method. There was no significant difference in the content of most amino acids in milk among the 4 groups. Only tyrosine, lysine, and isoleucine content in the milk of Jiangxi mothers were lower than that of Beijing mothers. (author's modified)     

Iodine status in vegans consuming a living food diet

The dietary intake and urinary output of iodine and the thyroid activity was measured in 12 living food eaters (people consuming uncooked, Lactobacilli rich vegan food) and omnivores. Seven day food record was used for calculating the dietary iodine intake, instrumental neutron activation analysis for measuring the urinary iodine output and RIA for determining of the thyroid hormones (TSH and FT4). The living food eaters were divided into two groups according to urinary iodine output: high iodine group (≥900 ug/d) and low iodine group (<200 ug/d). Thyroid activity in both groups was with in normal range. Dietary intake of iodine was dependent on the the use of seaweed. The highest amounts of dietary iodine observed in the present study, as assessed by the the urinary iodine output, can be harmful for susceptible subjects. On the other hand the calculated intake of iodine by living food eaters didn't fill the RDA. As an conclusion on a living food diet one has to ensure the sufficient intake of iodine by consuming seaweed or Kelp tablets daily. However the intake of these preparations needs to be kept at reasonble limits due to their possible high iodine content. More information of the iodine content of different seaweeds and seaweed products is needed.     

Evaluation of vitamin B12 status in Egypt IV: food consumption patterns among lactating mothers and their impact on the intake of the vitamin

The adequacy of vitamin B12 intake was assessed among 62 lactating mothers in the 2-32 weeks of lactation by an interactive 24-h recall and an open-ended food frequency questionnaire. Double portions of the foods consumed were sampled and assayed microbiologically for its vitamin B12 content. Based on the food item and its respective vitamin B12 content, combined with the usual portion size in grams and the frequency of consumption, a rapid calculator of approximate dietary vitamin B12 intake was developed. The estimated vitamin B12 intake averaged 4.17+/-0.74 microg/d. Only 25.8% of the lactating mothers had adequate vitamin B12 intake (>2.5 microg vitamin B12 daily). Three quarter of the studied population were consuming vitamin B12<2.5 microg/d. Out of those, 50% had estimated daily intake <2.0 microg/d. This percentage prevalence confirms the additional burden on the lactating mothers to satisfy the daily vitamin B12 requirement for its breast-fed baby.     

Dietary zinc intake and zinc concentrations of plasma, erythrocytes, and breast milk in antepartum and postpartum lactating and nonlactating women: a longitudinal study

The zinc status of a group of 23 lactating and 13 nonlactating women was assessed longitudinally from 37-wk gestation through 6 months postpartum. Dietary zinc intake was determined by chemical analysis of 3-day duplicate plate food composites. In addition, zinc concentrations were measured in plasma, erythrocytes, and breast milk. The mean dietary zinc intake of both groups of postpartum women as determined by direct analyses was 42% of the Recommended Dietary Allowances or less. The plasma and erythrocyte zinc concentrations were not significantly different between the lactating and nonlactating women. Plasma zinc concentration increased from the time of delivery to one month postpartum for both groups and did not significantly increase further through 6 months postpartum. Erythrocyte zinc decreased from delivery through 6 months postpartum for both groups. Breast milk zinc concentration decreased with the duration of lactation. The calculated zinc intake of infants from breast milk was less than 50% of the Recommended Dietary Allowances. There was no correlation of maternal dietary zinc intake or maternal plasma and erythrocyte zinc with the concentration of zinc in breast milk.     

Experimental maternal and neonatal folate status relationships in nonhuman primates

The influence of maternal dietary folic acid intake on folate status was studied in Cebus albifrons monkeys by feeding 10 or 250 micrograms/100 kcal dietary folic acid during pregnancy and 4 wk postpartum. Maternal, infant, and nonpregnant hematologic indices; blood and liver folate concentrations; and urinary formiminoglutamic acid excretion all varied with dietary folate intake and pregnancy status as did milk folate concentration in lactating dams. Maternal folate status, determined by plasma, red blood cell, and milk folate concentrations, as well as urinary formiminoglutamic acid excretion, all were correlated significantly with liver folate concentrations in neonates (r = 0.740, r = 0.919, r = 0.936, and r = -0.851, respectively). Results in these primates showed that neonatal folate status was related significantly to the dietary folate intake and folate status of the mother during pregnancy and lactation.     

Association between fat content of breast milk and maternal nutritional status and infants' weight in tabriz, iran

The aim of this study was to investigate the relationship between breast milk fat content with maternal anthropometric status, energy and macronutrient intake and weight for age Z-score of exclusively breastfed infants. Breast milk samples and information on energy and macronutrients intake (using 24-hour recall method for 3 days) were collected from 182 lactating women. Weight and height of mothers and infants were measured and the body mass index (BMI) and weight for age Z-score (WAZ) were calculated. The fat content of the milk samples was measured by the Gerber method. The mean daily energy intake was 2390 ± 405 kcal which was lower than the recommended values for mothers. The mean fat content of the milk samples was 3.52 ± 1.41 g/dl, which was significantly associated with dietary carbohydrate consumption (β= 0.39, P<0.004) and BMI (β= 0.28, P<0.02). A significant association between the WAZ of infants and maternal BMI (β= 0.36, P<0.001) was recorded. The WAZ of infants whose mothers' breast milk lipid content was more than 3 g/dl was significantly higher than those whose mothers had lower breast milk lipid content (P<0.031). Further studies need to be done on the effect of fat content of breast milk on infant's weight and how maternal factors regulate the composition of breast milk.     

Dietary evaluation of a low-iodine diet in Korean thyroid cancer patients preparing for radioactive iodine therapy in an iodine-rich region

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 ¹³¹I administration.

RESULTS

The median iodine intake was 290 µg/day on the usual diet and 63.2 µg/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.     

Impact of Maternal Daily Oral Low-Dose Vitamin A Supplementation on the Mother-Infant Pair: A Randomised Placebo-Controlled Trial in China

Background: The nutritional status of vitamin A in lactating mothers and infants is still not optimistic. Due to the dietary habits and dietary restrictions of postpartum customs in China, vitamin A supplementation has been advocated as a potential strategy to improve vitamin A status of lactating mothers with inadequate dietary vitamin A intake. Existing clinical trials are limited to single or double high-dose maternal administrations. However, in China, vitamin A supplements are readily available in the form of daily oral low-dose supplements, and the effect of these is unknown. This study aimed to evaluate the effects of daily oral low-dose vitamin A supplementation on the retinol levels in the serum and breast milk of lactating mothers and the health status of infants in China. Methods: Lactating mothers who met the inclusion criteria and planned to continue exclusive breastfeeding were randomly assigned to receive either daily oral vitamin A and D drops (one soft capsule of 1800 IU vitamin A and 600 IU vitamin D₂), or a matching placebo for 2 months. Before and after the intervention, dietary intake was investigated by instant photography, and the retinol concentration in maternal serum and breast milk was determined by ultra-high performance liquid chromatography-tandem mass spectrometry. During the trial, the health status of infants was diagnosed by a paediatrician or reported by lactating mothers. A total of 245 participants completed the study, with 117 in the supplementation group and 128 in the control group. Results: After the 2-month intervention, maternal serum retinol concentrations increased in the supplementation group with no change in the control group. Although breast milk retinol concentrations decreased significantly in both groups, the decrease in the supplementation group was significantly lower than that in the control group. However, maternal vitamin A supplementation was not associated with a lower risk of infant febrile illness, respiratory tract infection, diarrhoea, and eczema. Conclusions: Daily oral low-dose vitamin A supplementation is helpful in improving maternal vitamin A status, despite having no effect on infant health status through breast milk.     

Maternal dietary PUFAs intake and human milk content relationships during the first month of lactation

Maternal dietary fatty acids (FFAs) intake and corresponding human milk composition relationships have been assessed throughout the first month of lactation in 34 lactating women consecutively enrolled. All mothers were on their habitual diet. Food records (95 items) were administered to the mothers, six-times during the first month of lactation (1 day after delivery, 4, 7, 14, 21, and 28 days after colostrum appearance) and referred to maternal dietary intake of the day before. Milk collected on day 1 was considered as colostrum, day 4 and 7 samples as transitional milk, and day 14, 21 and 28 samples as mature milk. Five gas chromatographic analyses were performed on each sample. Statistics were made using Friedman's and Pearson's test. Maternal dietary saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) were significantly related to the corresponding milk pattern in the phase of transitional milk (P<0.01), while total polyunsaturated (PUFAs) content was significantly related only to the mature milk (P<0.01); in this phase about 42% of the variations occurring in PUFAs milk content can be related to variation of maternal PUFAs dietary intake. The results in the present study provide evidence of the relationships between maternal diet and milk composition. The degree of correlation between maternal diet and PUFAs milk content increases throughout milk maturational process and reaches significance only in mature milk. This would imply that advancing lactation, milk PUFAs provision sources gradually shift from adipose tissue catabolism to maternal diet.     

Carotenoid Profile in Maternal/Cord Plasma and Changes in Breast Milk along Lactation and Its Association with Dietary Intake: A Longitudinal Study in a Coastal City in Southern China

In this study, changes of carotenoids in breast milk were observed longitudinally for up to one year. Our study aimed to analyze the profile of carotenoids in breast milk and maternal/cord plasma and its correlation with dietary intake in Guangzhou. Plasma and breast milk samples of five stages during lactation (i.e., colostrum; transitional milk; and early, medium, and late mature milk) were collected from lactating mothers. The food frequency questionnaire (FFQ) was used for collecting data on dietary intake in the corresponding stages. Levels of lutein, zeaxanthin, β-cryptoxanthin, β-carotene, and lycopene were analyzed by high-performance liquid chromatography. We found that the total carotenoid level decreased gradually with the extension of lactation and eventually stabilized. Among them, the content of lutein increased from colostrum to transitional milk and decreased thereafter until it plateaued in the mature milk. Furthermore, lutein was reported as the dominant nutrient in maternal plasma, cord plasma, transitional milk, and mature milk at up to 400 days postpartum, while beta-carotene was predominant in colostrum. The content of β-carotenoid in middle and late mature breast milk was related to dietary intake (r = 1.690, p < 0.05). Carotenoid level in cord blood was lower than that in the mother’s plasma and was related to the carotenoid intake in the mother’s diet. Correlation of carotenoids between maternal and umbilical cord blood, breast milk, and maternal blood could well reflect the transport of carotenoids. These findings may help to guide mothers’ diets during breastfeeding.     

Trans fatty acids in human milk lipids: influence of maternal diet and weight loss

Geometric and positional isomers of octadecanoic acid in milk expressed during the first 9 weeks of lactation were determined for mothers delivering prematurely (PT) and at term (FT). Total C18:1 concentration was lower in PT than FT milk. C18:1 trans (elaidic acid) content was higher in PT and FT colostrum compared with subsequent milk samples. No relationship was observed between C18:1 trans level in milk and oleic acid, linoleic acid, total fatty acid levels, or volume of milk expressed. While gestational age and lactational stage appeared to affect the trans fatty acid pattern, the overriding influence was rate of maternal postpartum weight loss. Effect of weight loss on milk trans fatty acid levels was independent of maternal diet. Trans fatty acid content of milk as a function of recent maternal fat intake was also demonstrated. This study indicates that infants receiving human milk ingest levels of trans fatty acids reflecting short and long term maternal diet.