Universal Salt Iodization Provides Sufficient Dietary Iodine to Achieve Adequate Iodine Nutrition during the First 1000 Days: A Cross-Sectional Multicenter Study.

Background: Dietary iodine requirements are high during pregnancy, lactation, and infancy, making women and infants vulnerable to iodine deficiency. Universal salt iodization (USI) has been remarkably successful for preventing iodine deficiency in the general population, but it is uncertain if USI provides adequate iodine intakes during the first 1000 d. Objective: We set out to assess if USI provides sufficient dietary iodine to meet the iodine requirements and achieve adequate iodine nutrition in all vulnerable population groups. Methods: We conducted an international, cross-sectional, multicenter study in 3 study sites with mandatory USI legislation. We enrolled 5860 participants from 6 population groups (school-age children, nonpregnant nonlactating women of reproductive age, pregnant women, lactating women, 0-6-mo-old infants, and 7-24-mo-old infants) and assessed iodine status [urinary iodine concentration (UIC)] and thyroid function in Linfen, China (n = 2408), Tuguegarao, the Philippines (n = 2512), and Zagreb, Croatia (n = 940). We analyzed the iodine concentration in household salt, breast milk, drinking water, and cow's milk. Results: The salt iodine concentration was low (<15 mg/kg) in 2.7%, 33.6%, and 3.1%, adequate (15-40 mg/kg) in 96.3%, 48.4%, and 96.4%, and high (>40 mg/kg) in 1.0%, 18.0%, and 0.5% of household salt samples in Linfen (n = 402), Tuguegarao (n = 1003), and Zagreb (n = 195), respectively. The median UIC showed adequate iodine nutrition in all population groups, except for excessive iodine intake in school-age children in the Philippines and borderline low intake in pregnant women in Croatia. Conclusions: Salt iodization at ∼25 mg/kg that covers a high proportion of the total amount of salt consumed supplies sufficient dietary iodine to ensure adequate iodine nutrition in all population groups, although intakes may be borderline low during pregnancy. Large variations in salt iodine concentrations increase the risk for both low and high iodine intakes. Strict monitoring of the national salt iodization program is therefore essential for optimal iodine nutrition. This trial was registered at clinicaltrials.gov as NCT02196337.

Breast Milk Iodine Concentration Is a More Accurate Biomarker of Iodine Status Than Urinary Iodine Concentration in Exclusively Breastfeeding Women.

Background: Iodine status in populations is usually assessed by the median urinary iodine concentration (UIC). However, iodine is also excreted in breast milk during lactation; thus, breast milk iodine concentration (BMIC) may be a promising biomarker of iodine nutrition in lactating women. Whether the mammary gland can vary fractional uptake of circulating iodine in response to changes in dietary intake is unclear.Objective: We evaluated UIC and BMIC as biomarkers for iodine status in lactating women with a wide range of iodine intakes.Methods: We recruited 866 pairs of lactating mothers and exclusively breastfed infants from 3 iodine-sufficient study sites: Linfen, China (n = 386); Tuguegarao, Philippines (n = 371); and Zagreb, Croatia (n = 109). We also recruited iodine-deficient lactating women from Amizmiz, Morocco (n = 117). We collected urine and breast milk samples and measured UIC and BMIC.Results: In the 3 iodine-sufficient sites, a pooled regression analysis of the estimated iodine excretion revealed higher fractional iodine excretion in breast milk than in urine at borderline low iodine intakes. In contrast, in the iodine-deficient site in Morocco, a constant proportion (∼33%) of total iodine was excreted into breast milk.Conclusions: In iodine-sufficient populations, when iodine intake in lactating women is low, there is increased partitioning of iodine into breast milk. For this reason, maternal UIC alone may not reflect iodine status, and BMIC should also be measured to assess iodine status in lactating women. Our data suggest a BMIC reference range (2.5th and 97.5th percentiles) of 60-465 µg/kg in exclusively breastfeeding women. This trial was registered at clinicaltrials.gov as NCT02196337.

More than two-thirds of dietary iodine in children in northern Ghana is obtained from bouillon cubes containing iodized salt.

OBJECTIVE: Bouillon cubes are widely consumed by poor households in sub-Saharan Africa. Because their main ingredient is salt, bouillon cubes could be a good source of iodine if iodized salt is used in their production and if their consumption by target groups is high. Our objective was to measure the iodine content of bouillon cubes, estimate their daily intake in school-aged children and evaluate their potential contribution to iodine intakes. DESIGN: In a cross-sectional study, we measured urinary iodine concentrations (UIC) and estimated total daily iodine intakes. We administered a questionnaire on usage of bouillon cubes. We measured the iodine content of bouillon cubes, household salt, drinking-water and milk products. SETTING: Primary schools in northern Ghana. SUBJECTS: Schoolchildren aged 6-13 years. RESULTS: Among school-aged children (n 250), median (interquartile range) UIC and estimated iodine intake were 242 (163-365) µg/l and 129 (85-221) µg/d, indicating adequate iodine status. Median household salt iodine concentration (n 100) was only 2·0 (0·83-7·4) µg/g; 72 % of samples contained <5 µg iodine/g. Iodine concentrations in drinking-water and milk-based drinks were negligible. Median iodine content of bouillon cubes was 31·8 (26·8-43·7) µg/g, with large differences between brands. Estimated median per capita consumption of bouillon cubes was 2·4 (1·5-3·3) g/d and median iodine intake from bouillon cubes was 88 (51-110) µg/d. CONCLUSIONS: Despite low household coverage with iodized salt, iodine nutrition in school-aged children is adequate and an estimated two-thirds of their dietary iodine is obtained from bouillon cubes.

Estimation of the Prevalence of Inadequate and Excessive Iodine Intakes in School-Age Children from the Adjusted Distribution of Urinary Iodine Concentrations from Population Surveys.

BACKGROUND: The urinary iodine concentration (UIC), a biomarker of iodine intake, is used to assess population iodine status by deriving the median UIC, but this does not quantify the percentage of individuals with habitually deficient or excess iodine intakes. Individuals with a UIC <100 µg/L or ≥300 µg/L are often incorrectly classified as having deficient or excess intakes, but this likely overestimates the true prevalence. OBJECTIVE: Our aim was to estimate the prevalence of inadequate and excess iodine intake in children (aged 4-14 y) with the distribution of spot UIC from iodine surveys. METHODS: With the use of data from national iodine studies (Kuwait, Oman, Thailand, and Qatar) and a regional study (China) in children (n = 6117) in which a repeat UIC was obtained in a subsample (n = 1060), we calculated daily iodine intake from spot UICs from the relation between body weight and 24-h urine volume and within-person variation by using the repeat UIC. We also estimated pooled external within-person proportion of total variances by region. We used within-person variance proportions to obtain the prevalence of inadequate or excess usual iodine intake by using the Estimated Average Requirement (EAR)/Tolerable Upper Intake Level (UL) cutoff method. RESULTS: Median UICs in Kuwait, Oman, China, Thailand, and Qatar were 132, 192, 199, 262, and 333 µg/L, respectively. Internal within-person variance proportions ranged from 25.0% to 80.0%, and pooled regional external estimates ranged from 40.4% to 77.5%. The prevalence of inadequate and excess intakes as defined by the adjusted EAR/UL cutoff method was ∼45-99% lower than those defined by a spot UIC <100 µg/L or ≥300 µg/L (P < 0.01). CONCLUSIONS: Applying the EAR/UL cutoff method to iodine intakes from adjusted UIC distributions is a promising approach to estimate the number of individuals with deficient or excess iodine intakes.

Vitamins, the gut microbiome and gastrointestinal health in humans.

The gut microbiome plays important roles in the maintenance of host health and the pathogenesis of many diseases. Diet is a key modulator of the gut microbiome. There is increasing evidence that nutrients other than fermentable fiber affect the gut microbial composition. In this review, we discuss the effects of vitamins on the gut microbiome, and related gastrointestinal health, based on in vitro, animal and human studies. Some vitamins, when provided in large doses or when delivered to the large intestine, have been shown to beneficially modulate the gut microbiome by increasing the abundance of presumed commensals (vitamins A, B2, D, E, and beta-carotene), increasing or maintaining microbial diversity (vitamins A, B2, B3, C, K) and richness (vitamin D), increasing short chain fatty acid production (vitamin C), or increasing the abundance of short chain fatty acid producers (vitamins B2, E). Others, such as vitamins A and D, modulate the gut immune response or barrier function, thus, indirectly influencing gastrointestinal health or the microbiome. Future research is needed to explore these potential effects and to elucidate the underlying mechanisms and host health benefits.

Iron bioavailability from bouillon fortified with a novel ferric phytate compound: a stable iron isotope study in healthy women (part II).

Bouillon cubes are widely consumed and when fortified with iron could contribute in preventing iron deficiency. We report the development (part I) and evaluation (current part II) of a novel ferric phytate compound to be used as iron fortificant in condiments such as bouillon. Ferric pyrophosphate (FePP), is the compound of choice due to its high stability in foods, but has a modest absorption in humans. Our objective was to assess iron bioavailability from a novel iron fortificant consisting of ferric iron complexed with phytic acid and hydrolyzed corn protein (Fe-PA-HCP), used in bouillon with and without an inhibitory food matrix. In a randomised single blind, cross-over study, we measured iron absorption in healthy adult women (n = 22). In vitro iron bioaccessibility was assessed using a Caco-2 cell model. Iron absorption from Fe-PA-HCP was 1.5% and 4.1% in bouillon with and without inhibitory matrix, respectively. Relative iron bioavailability to FeSO4 was 2.4 times higher than from FePP in bouillon (17% vs 7%) and 5.2 times higher when consumed with the inhibitory meal (41% vs 8%). Similar results were found in vitro. Fe-PA-HCP has a higher relative bioavailability versus FePP, especially when bouillon is served with an inhibitory food matrix.

A dose-response crossover iodine balance study to determine iodine requirements in early infancy.

BACKGROUND: Optimal iodine intake during infancy is critical for brain development, but no estimated average requirement (EAR) is available for this age group. OBJECTIVE: We measured daily iodine intake, excretion, and retention over a range of iodine intakes in early infancy to determine the minimum daily intake required to achieve iodine balance. DESIGN: In a dose-response crossover study, we randomly assigned healthy infants (n = 11; mean ± SD age 13 ± 3 wk) to sequentially consume over 33 d 3 infant formula milks (IFMs) containing 10.5, 19.3, and 38.5 µg I/100 kcal, respectively. Each IFM was consumed for 11 d, consisting of a 6-d run-in period followed by a 4-d balance period and 1 run-out day. RESULTS: Iodine intake (mean ± SD: 54.6 ± 8.1, 142.3 ± 23.1, and 268.4 ± 32.6 µg/d), excretion (55.9 ± 8.6, 121.9 ± 21.7, and 228.7 ± 39.3 µg/d), and retention (-1.6 ± 8.3, 20.6 ± 21.6, and 39.8 ± 34.3 µg/d) differed among the low, middle, and high iodine IFM groups (P < 0.001 for all). There was a linear relation between daily iodine intake and both daily iodine excretion and daily iodine retention. Zero balance (iodine intake = iodine excretion, iodine retention = 0 µg/d) was achieved at a daily iodine intake of 70 µg (95% CI: 60, 80 µg). CONCLUSION: Our data indicate the iodine requirement in 2- to 5-mo-old infants is 70 µg/d. Adding an allowance for accumulation of thyroidal iodine stores would produce an EAR of 72 µg and a recommended dietary allowance of 80 µg. This trial was registered at clinicaltrials.gov as NCT02045784.

Optimization of a New Mass Spectrometry Method for Measurement of Breast Milk Iodine Concentrations and an Assessment of the Effect of Analytic Method and Timing of Within-Feed Sample Collection on Breast Milk Iodine Concentrations.

BACKGROUND: Breast milk iodine concentration (BMIC) may be an indicator of iodine status during lactation, but there are few data comparing different analytical methods or timing of sampling. The aims of this study were: (i) to optimize a new inductively coupled plasma mass spectrometry (ICP-MS) method; and (ii) to evaluate the effect of analytical method and timing of within-feed sample collection on BMIC. METHODS: The colorimetric Sandell-Kolthoff method was evaluated with (a) or without (b) alkaline ashing, and ICP-MS was evaluated using a new (129)I isotope ratio approach including Tellurium (Te) for mass bias correction (c) or external standard curve (d). From iodine-sufficient lactating women (n = 97), three samples were collected within one breast-feeding session (fore-, mid-, and hind-feed samples) and BMIC was analyzed using (c) and (d). RESULTS: Iodine recovery from NIST SRM1549a whole milk powder for methods (a)-(d) was 67%, 24%, 105%, and 102%, respectively. Intra- and inter-assay coefficients of variation for ICP-MS comparing (c) and (d) were 1.3% versus 5.6% (p = 0.04) and 1.1% versus 2.4% (p = 0.33). The limit of detection (LOD) was lower for (c) (0.26 µg/kg) than it was for (d) (2.54 µg/kg; p = 0.02). Using (c), the median [95% confidence interval (CI) obtained by bootstrap] BMIC (µg/kg) in foremilk (179 [CI 161-206]) and in mid-feed milk (184 [CI 160-220]) were not significantly different (p = 0.017), but were higher than in hindmilk (175 [CI 153-216]; p < 0.001). In foremilk using (d), BMIC was 199 ([CI 182-257]; p < 0.001 vs. (c)). The variation in BMIC comparing (c) and (d) (13%) was greater than variation within feeding (5%; p < 0.001). CONCLUSIONS: Because of poor recoveries, (a) and (b) should not be used to measure BMIC. Compared with (d), (c) has the advantages of higher precision and a lower LOD. In iodine-sufficient women, BMIC shows low variation within a breast-feeding session, so timing of sampling is not a major determinant of BMIC.

Breast-Milk Iodine Concentrations, Iodine Status, and Thyroid Function of Breastfed Infants Aged 2-4 Months and Their Mothers Residing in a South African Township.

OBJECTIVE: Lactating women and their infants are susceptible to iodine deficiency and iodine excess. In South Africa, no data exist on the iodine status and thyroid function of these vulnerable groups. METHODS: In a cross-sectional study, urinary iodine concentrations (UIC), thyroid function, and breast-milk iodine concentrations (BMIC) were assessed in 100 lactating women from a South African township and their 2-4-month-old breastfed infants. Potential predictors of UIC, thyroid function, and BMIC, including household salt iodine concentrations (SIC) and maternal sodium excretion, were also investigated. RESULTS: The median (25th-75th percentile) UIC was 373 (202-627) µg/L in infants and 118 (67-179) µg/L in mothers. Median household SIC was 44 (27-63) ppm. Household SIC and maternal urinary sodium excretion predicted UIC of lactating mothers. Median BMIC was 179 (126-269) µg/L. Age of infants, SIC, and maternal UIC predicted BMIC. In turn, infant age and BMIC predicted UIC of infants. Forty-two percent of SIC values were within the South African recommended salt iodine fortification level at production of 35-65 ppm, whilst 21% of SIC were >65 ppm. Thyroid-stimulating hormone, total thyroxine, and thyroglobulin concentrations in the dried whole blood spot specimens from the infants were 1.3 (0.8-1.9) mU/L, 128±33 mmol/L, and 77.1 (56.3-105.7) µg/L, respectively, and did not correlate with infant UIC or BMIC. CONCLUSION: Our results suggest that the salt fortification program in South Africa provides adequate iodine to lactating women and indirectly to their infants via breast milk. However, monitoring of salt iodine content of the mandatory salt iodization program in South Africa is important to avoid over-iodization of salt.

Influence of foam structure on the release kinetics of volatiles from espresso coffee prior to consumption.

The relationship between the physical structure of espresso coffee foam, called crema, and the above-the-cup aroma release was studied. Espresso coffee samples were produced using the Nespresso extraction system. The samples were extracted with water with different levels of mineral content, which resulted in liquid phases with similar volatile profiles but foams with different structure properties. The structure parameters foam volume, foam drainage, and lamella film thickness at the foam surface were quantified using computer-assisted microscopic image analysis and a digital caliper. The above-the-cup volatile concentration was measured online by using PTR-MS and headspace sampling. A correlation study was done between crema structure parameters and above-the-cup volatile concentration. In the first 2.5 min after the start of the coffee extraction, the presence of foam induced an increase of concentration of selected volatile markers, independently if the crema was of high or low stability. At times longer than 2.5 min, the aroma marker concentration depends on both the stability of the crema and the volatility of the specific aroma compounds. Mechanisms of above-the-cup volatile release involved gas bubble stability, evaporation, and diffusion. It was concluded that after the initial aroma burst (during the first 2-3 min after the beginning of extraction), for the present sample space a crema of high stability provides a stronger aroma barrier over several minutes.

Preparation of passion fruit-typical 2-alkyl ester enantiomers via lipase-catalyzed kinetic resolution.

The preparation of ester enantiomers (acetates, butanoates, hexanoates and octanoates) of the secondary alcohols 2-pentanol, 2-heptanol and 2-nonanol via lipase-catalyzed kinetic resolutions was investigated. Conversion rates and stereochemical courses of esterification and hydrolysis reactions catalyzed by commercially available enzyme preparations were followed for the homologous series of these passion fruit-typical 2-alkyl esters by capillary gas chromatography using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta-cyclodextrin as chiral stationary phase. An efficient method was developed to prepare the ester enantiomers via lipase-catalyzed esterifications: optically pure (R)-2-alkyl esters (ee > 99.9%) were obtained by esterification of the racemic alcohols with enantioselective Candida antarctica lipase B (immobilized) as catalyst. The subsequent esterification of the unreacted alcohols using lipase from Candida cylindracea yielded the optically enriched (S)-esters (ee > 81.4%). The separation of the products via liquid solid chromatography using a mixture of silica gel and aluminum oxide (basic) resulted in high chemical purities and yields (> 40 mol %).