Epidemiology of iodine deficiency: Salt iodisation and iodine status.

Universal salt iodisation (USI) and iodine supplementation are highly effective strategies for preventing and controlling iodine deficiency. USI is now implemented in nearly all countries worldwide, and two-thirds of the world's population is covered by iodised salt. The number of countries with iodine deficiency as a national public health problem has decreased from 110 in 1993 to 47 in 2007. Still one-third of households lack access to adequately iodised salt. Iodine deficiency remains a major threat to the health and development of populations around the world, particularly in children and pregnant women in low-income countries. Data on iodine status are available from 130 countries and approximately one-third of the global population is estimated to have a low iodine intake based on urinary iodine (UI) concentrations. Insufficient control of iodine fortification levels has led to excessive iodine intakes in 34 countries. The challenges ahead lie in ensuring higher coverage of adequately iodised salt, strengthening regular monitoring of salt iodisation and iodine status in the population, together with targeted interventions for vulnerable population groups.

Achievements, challenges, and promising new approaches in vitamin and mineral deficiency control.

Micronutrient deficiencies (MNDs) contribute significantly to the world's disease and mortality burden. Global efforts addressing MNDs have achieved significant yet heterogeneous progress across and within regions and countries. For vitamin A and iodine interventions, enhancing achievements in coverage require further political and financial commitment and targeting of hard-to-reach populations. Anemia control must focus on prevention among preschoolers and adolescent women and on integrated public health programs. Current international guidelines on iron supplementation and cut-off values for anemia need revision. For zinc, advocacy to accelerate the application of revised diarrhea management guidelines is critical, as are efficacy studies on food-based interventions and preventive supplementation.

Iodine deficiency in 2007: global progress since 2003.

BACKGROUND: Iodine deficiency is a global public health problem, and estimates of the extent of the problem were last produced in 2003. OBJECTIVES: To provide updated global estimates of the magnitude of iodine deficiency in 2007, to assess progress since 2003, and to provide information on gaps in the data available. METHODS: Recently published, nationally representative data on urinary iodine (UI) in school-age children collected between 1997 and 2006 were used to update country estimates of iodine nutrition. These estimates, alongside the 2003 estimates for the remaining countries without new data, were used to generate updated global and regional estimates of iodine nutrition. The median UI was used to classify countries according to the public health significance of their iodine nutrition status. Progress was measured by comparing current prevalence figures with those from 2003. The data available for pregnant women by year of survey were also assessed. RESULTS: New UI data in school-age children were available for 41 countries, representing 45.4% of the world's school-age children. These data, along with previous country estimates for 89 countries, are the basis for the estimates and represent 91.1% of this population group. An estimated 31.5% of school-age children (266 million) have insufficient iodine intake. In the general population, 2 billion people have insufficient iodine intake. The number of countries where iodine deficiency is a public health problem is 47. Progress has been made: 12 countries have progressed to optimal iodine status, and the percentage ofschool-age children at risk of iodine deficiency has decreased by 5%. However, iodine intake is more than adequate, or even excessive, in 34 countries: an increase from 27 in 2003. There are insufficient data to estimate the global prevalence of iodine deficiency in pregnant women. CONCLUSIONS: Global progress in controlling iodine deficiency has been made since 2003, but efforts need to be accelerated in order to eliminate this debilitating health issue that affects almost one in three individuals globally. Surveillance systems need to be strengthened to monitor both low and excessive intakes of iodine.

Conclusions of the Joint WHO/UNICEF/IAEA/IZiNCG Interagency Meeting on Zinc Status Indicators.

Zinc deficiency is an important cause of morbidity in developing countries, particularly among young children, yet little information is available on the global prevalence of zinc deficiency. A working group meeting was convened by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF), the International Atomic Energy Agency (IAEA), and the International Zinc Nutrition Consultative Group (IZiNCG) to review methods of assessing population zinc status and provide standard recommendations for the use of specific biochemical, dietary, and functional indicators of zinc status in populations. The recommended biochemical indicator is the prevalence of serum zinc concentration less than the age/sex/time of day-specific cutoffs; when the prevalence is greater than 20%, intervention to improve zinc status is recommended. For dietary indicators, the prevalence (or probability) of zinc intakes below the appropriate estimated average requirement (EAR) should be used, as determined from quantitative dietary intake assessments. Where the prevalence of inadequate intakes of zinc is greater than 25%, the risk of zinc deficiency is considered to be elevated. Previous studies indicate that stunted children respond to zinc supplementation with increased growth. When the prevalence of low height-for-age is 20% or more, the prevalence of zinc deficiency may also be elevated. Ideally, all three types of indicators would be used together to obtain the best estimate of the risk of zinc deficiency in a population and to identify specific subgroups with elevated risk. These recommended indicators should be applied for national assessment of zinc status and to indicate the need for zinc interventions. The prevalence of low serum zinc and inadequate zinc intakes may be used to evaluate their impact on the target population's zinc status.

Evaluation of vitamin A supplementation regimens in Ghanaian postpartum mothers with the use of the modified-relative-dose-response test.

BACKGROUND: Vitamin A deficiency is an important public health problem in many developing countries. Women of childbearing age and children are documented as the most affected groups. OBJECTIVE: The objective was to determine the length of time mothers are protected postpartum against vitamin A depletion after receiving either 400,000 IU vitamin A in 2 divided doses or 200,000 IU as a single dose plus a placebo 24 h apart. DESIGN: Mothers (n = 168) were recruited by trained fieldworkers 7-10 d after delivery. Modified-relative-dose-response (MRDR) tests were performed at baseline in 167 women, and vitamin A was administered within 6 wk after delivery. The women were randomly assigned to 2 main treatment groups, and each treatment group was divided into 3 follow-up subgroups. Each subgroup was invited back once at month 1, 3, or 5 for a second MRDR test. RESULTS: The serum retinol concentration and the MRDR value were 1.4 +/- 0.5 micromol/L and 0.048 +/- 0.037, respectively, at baseline. A significant improvement in vitamin A status occurred after vitamin A treatment as assessed by the MRDR test (P < 0.0001). Serum retinol concentrations were not different after vitamin A treatment (P = 0.87). CONCLUSIONS: The mothers had marginally depleted liver reserves of vitamin A at baseline on the basis of MRDR test results. Liver reserves of vitamin A significantly improved in both treatment groups, and the improvement was maintained for >or= 5 mo.

Micronutrient deficiencies and gender: social and economic costs.

Vitamin and mineral deficiencies adversely affect a third of the world's people. Consequently, a series of global goals and a serious amount of donor and national resources have been directed at such micronutrient deficiencies. Drawing on the extensive experience of the authors in a variety of institutional settings, the article used a computer search of the published scientific literature of the topic, supplemented by reports and published and unpublished work from the various agencies. In examining the effect of sex on the economic and social costs of micronutrient deficiencies, the paper found that: (1) micronutrient deficiencies affect global health outcomes; (2) micronutrient deficiencies incur substantial economic costs; (3) health and nutrition outcomes are affected by sex; (4) micronutrient deficiencies are affected by sex, but this is often culturally specific; and finally, (5) the social and economic costs of micronutrient deficiencies, with particular reference to women and female adolescents and children, are likely to be considerable but are not well quantified. Given the potential impact on reducing infant and child mortality, reducing maternal mortality, and enhancing neuro-intellectual development and growth, the right of women and children to adequate food and nutrition should more explicitly reflect their special requirements in terms of micronutrients. The positive impact of alleviating micronutrient malnutrition on physical activity, education and productivity, and hence on national economies suggests that there is also an urgent need for increased effort to demonstrate the cost of these deficiencies, as well as the benefits of addressing them, especially compared with other health and nutrition interventions.

Determining median urinary iodine concentration that indicates adequate iodine intake at population level.

OBJECTIVE: Urinary iodine concentration is the prime indicator of nutritional iodine status and is used to evaluate population-based iodine supplementation. In 1994, WHO, UNICEF and ICCIDD recommended median urinary iodine concentrations for populations of 100- 200 micro g/l, assuming the 100 micro g/l threshold would limit concentrations <50 micro g/l to 100 micro g/l. The total population was 55 892, including 35 661 (64%) schoolchildren. Median urinary iodine concentrations were 111-540 (median 201) micro g/l for all populations, 100-199 micro g/l in 23 (48%) populations and >/=200 micro g/l in 25 (52%). The frequencies of values <50 micro g/l were 0-20.8 (mean 4.8%) overall and 7.2% and 2.5% in populations with medians of 100-199 micro g/l and >200 micro g/l, respectively. The frequency reached 20% only in two places where iodine had been supplemented for <2 years. CONCLUSION: The frequency of urinary iodine concentrations <50 micro g/l in populations with median urinary iodine concentrations >/=100 micro g/l has been overestimated. The threshold of 100 micro g/l does not need to be increased. In populations, median urinary iodine concentrations of 100-200 micro g/l indicate adequate iodine intake and optimal iodine nutrition.

[Iodine deficiency: current situation and future prospects]. / La carence iodée: bilan et perspectives pour le futur.

Iodine deficiency disorders (IDD) is a major public health problem worldwide. WHO estimates that 740 million people are currently affected by goitre. The consequences of iodine deficiency on health are the results of hypothyroidism and the main one is impaired development of foetal brain. IDD is the first cause of preventable brain damage in children. The recommended strategy to correct IDD rests upon salt iodisation. Over the last 20 years, the international community mobilised to eliminate IDD under the leadership of WHO, Unicef and ICCIDD. It resulted in remarkable progress in IDD control, especially in Africa and in South East Asia where the endemic is the most severe. It is estimated that 68% of the populations of affected countries have currently access to iodised salt. However, out of the 130 affected countries, about 30 have no programme. Besides, salt quality control and monitoring of population iodine status are still weak in many countries, thus exposing the population to an excessive iodine intake and subsequently to the risk of iodine-induced hyperthyroidism. In addition, IDD is re-emerging in some countries, especially in Eastern Europe after it had disappeared. In order to reach the goal of IDD elimination, it is important to insist on the sustainability of salt iodisation programmes, which implies an increased commitment of both health authorities and representatives of the salt industry.