The current performance indicator for universal salt iodisation (USI) is the percentage of households using adequately iodised salt. However, the proportion of dietary salt from household salt is decreasing with the increase in consumption of processed foods and condiments globally. This paper reports on case studies supported by the Global Alliance for Improved Nutrition (GAIN)-UNICEF USI Partnership Project to investigate processed food industry use of adequately iodised salt in contrasting national contexts. Studies were conducted in Egypt, Indonesia, the Philippines, the Russian Federation, and Ukraine. In all cases, the potential iodine intake from iodised salt in selected food products was modelled according to the formula: quantity of salt per unit of food product × minimum regulated iodine level of salt at production × average daily per capita consumption of the product. The percent of adult recommended nutrient intake for iodine potentially provided by the average daily intake of bread and frequently consumed foods and condiments was from 10% to 80% at the individual product level. The potential contribution to iodine intake from the use of iodised salt in the processed food industry is of growing significance. National USI strategies should encourage co-operative industry engagement and include regulatory monitoring of iodised salt use in the food industry in order to achieve optimal population iodine status.
In 2013, the World Health Organization (WHO) called for joint surveillance of population salt and iodine intakes using urinary analysis. 24-h urine collection is considered the gold standard for salt intake assessment, but there is an emerging consensus that casual urine sampling can provide comparable information for population-level surveillance. Our review covers the use of the urinary sodium concentration (UNaC) and the urinary iodine concentration (UIC) from casual urine samples to estimate salt intakes and to partition the sources of iodine intakes. We reviewed literature on 24-h urinary sodium excretion (UNaE) and UNaC and documented the use of UNaC for national salt intake monitoring. We combined information from our review of urinary sodium with evidence on urinary iodine to assess the appropriateness of partitioning methods currently being adapted for cross-sectional survey analyses. At least nine countries are using casual urine collection for surveillance of population salt intakes; all these countries used single samples. Time trend analyses indicate that single UNaC can be used for monitoring changes in mean salt intakes. However; single UNaC suffers the same limitation as single UNaE; i.e., an estimate of the proportion excess salt intake can be biased due to high individual variability. There is evidence, albeit limited, that repeat UNaC sampling has good agreement at the population level with repeat UNaE collections; thus permitting an unbiased estimate of the proportion of excess salt intake. High variability of UIC and UNaC in single urine samples may also bias the estimates of dietary iodine intake sources. Our review concludes that repeated collection, in a sub-sample of individuals, of casual UNaC data would provide an immediate practical approach for routine monitoring of salt intake, because it overcomes the bias in estimates of excess salt intake. Thus we recommend more survey research to expand the evidence-base on predicted-UNaE from repeat casual UNaC sampling. We also conclude that the methodology for partitioning the sources of iodine intake based on the combination of UIC and UNaC measurements in casual urine samples can be improved by repeat collections of casual data; which helps to reduce regression dilution bias. We recommend more survey research to determine the effect of regression dilution bias and circadian rhythms on the partitioning of dietary iodine intake sources.
The effect of anthropometric status on the efficacy of an oral supplement of iodised oil (1 ml Lipiodol Ultrafluide, 490 mg I; Laboratoire Guerbet, Aulnay-sous-Bois, France) was examined in 8–10-year-old schoolchildren (n 197) of Ntcheu, a severely I-deficient district of Malawi. The study was a controlled trial using the I concentration of casual urine samples to monitor the I status. The median urinary I concentration increased from 0·15 μmol/l at baseline (51·3 % of children < 0·16 μmol/l, 89·7 % < 0·40 μmol/l, 95·7 % 0·79 μmol/l) to 0·32 μmol/l at 40 weeks (29·1 % of the children < 0·16 μmol/l, 71·0 % < 0·40 μmol/l, 96·1 % < 0·79 μmol/l) while the total goitre prevalence fell from 63 % to 21 %. Variables of efficacy were estimated from a hyperbolic function describing the longitudinal pattern of urinary I excretion after the dose. The I retention and I elimination rate, and the periods of protection from mild (< 0·79 μmol/l) or moderate (< 0·40 μmol/l) I deficiency were obtained for groups of children with differing anthropometric status at baseline. Initial height-for-age and mid upper-arm circumference were not significantly related to efficacy. However, both the I retention and I elimination rate were reduced in children with lower initial weight-for-height. Children with lower skinfold thickness at baseline also had reduced I retention, which resulted in shorter protection periods from recurrent moderate and mild I deficiency. The efficacy of the oral iodised-oil supplement was not related to changes in anthropometric status during follow-up, nor was it related to the consumption of a food supplement of 1610 kJ immediately before the iodised-oil dose. Very low (< 0·16 μmol/l) urinary I concentration, and the presence of goitre at baseline were both associated with higher I retention and elimination rate. Children with goitre at baseline were found to have a prolonged duration of protection against recurrent moderate I deficiency. We conclude that in apparently healthy schoolchildren in I-deficient areas, general anthropometric status has a little influence on the efficacy of oral iodised oil for correcting I deficiency.
27 December 2017 in Clinical and experimental thyroidology
Стратегия всеобщего йодирования соли стала мощным импульсом для стран Юго-Восточной Европы и Центральной Азии за период с 2000 по 2009 г. К концу первого десятилетия несколько стран региона уже достигли оптимального потребления йода; другие страны стремительно двигались к достижению той же цели и лишь в нескольких странах прогресс в сторону всеобщего йодирования соли оставался обнадеживающим. В данной статье приводятся данные субрегиональных семинаров (для стран Восточной Европы, Центральной Азии и Юго-Восточной Европы), проведенных в 2015 и 2016 гг. Оба семинара демонстрируют стремление стран регионов Юго-Восточной Европы и Центральной Азии к устойчивому устранению йодного дефицита. Несмотря на определенные недостатки, данные, полученные от стран региона, не предполагают каких-либо серьезных препятствий на пути к победе над йодным дефицитом. Тем не менее, России и Украине необходимо приложить больше усилий для развития и рационализации стратегии всеобщего йодирования соли, так как именно эти страны находятся в списке отстающих в данном вопросе.
The current performance indicator for universal salt iodization (USI) is the percent of households using adequately iodized salt. However, the proportion of dietary salt from household salt is decreasing with the increase in consumption of processed foods and condiments globally. This paper reports on case studies supported by the GAIN-UNICEF USI Partnership Project to investigate processed food industry use of adequately iodized salt in contrasting national contexts. Studies were conducted in Egypt, Indonesia, the Philippines, the Russian Federation, and Ukraine. In all cases, the potential iodine intake from iodized salt in selected food products was modelled according to the formula: Quantity of salt per unit of food product x minimum regulated iodine level of salt at production x average daily per capita consumption of the product. The percent of adult recommended nutrient intake for iodine potentially provided by the average daily intake of bread and frequently consumed foods and condiments was from 10% to 80% at the individual product level. The potential contribution to iodine intake from the use of iodized salt in the processed food industry is of growing significance. National USI strategies should encourage co-operative industry engagement and include regulatory monitoring of iodized salt use in the food industry in order to achieve optimal population iodine status.