Bruno de Benoist

Worldwide prevalence of anaemia, WHO Vitamin and Mineral Nutrition Information System, 1993-2005.

OBJECTIVE To provide current global and regional estimates of anaemia prevalence and number of persons affected in the total population and by population subgroup. SETTING AND DESIGN We used anaemia prevalence data from the WHO Vitamin and Mineral Nutrition Information System for 1993-2005 to generate anaemia prevalence estimates for countries with data representative at the national level or at the first administrative level that is below the national level. For countries without eligible data, we employed regression-based estimates, which used the UN Human Development Index (HDI) and other health indicators. We combined country estimates, weighted by their population, to estimate anaemia prevalence at the global level, by UN Regions and by category of human development. RESULTS Survey data covered 48.8 % of the global population, 76.1 % of preschool-aged children, 69.0 % of pregnant women and 73.5 % of non-pregnant women. The estimated global anaemia prevalence is 24.8 % (95 % CI 22.9, 26.7 %), affecting 1.62 billion people (95 % CI 1.50, 1.74 billion). Estimated anaemia prevalence is 47.4 % (95 % CI 45.7, 49.1 %) in preschool-aged children, 41.8 % (95 % CI 39.9, 43.8 %) in pregnant women and 30.2 % (95 % CI 28.7, 31.6 %) in non-pregnant women. In numbers, 293 million (95 % CI 282, 303 million) preschool-aged children, 56 million (95 % CI 54, 59 million) pregnant women and 468 million (95 % CI 446, 491 million) non-pregnant women are affected. CONCLUSION Anaemia affects one-quarter of the worlds population and is concentrated in preschool-aged children and women, making it a global public health problem. Data on relative contributions of causal factors are lacking, however, which makes it difficult to effectively address the problem.

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 worlds 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 of school-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 a WHO Technical Consultation on Folate and Vitamin B12 Deficiencies

Folate and vitamin B12 deficiencies occur primarily as a result of insufficient dietary intake or, especially in the case of vitamin B12 deficiency in the elderly, poor absorption. Folate is present in high concentrations in legumes, leafy green vegetables, and some fruits, so lower intakes can be expected where the staple diet consists of unfortified wheat, maize, or rice, and when the intake of legumes and folate-rich vegetables and fruits is low. This situation can occur in both wealthy and poorer countries. Animal-source foods are the only natural source of vitamin B12, so deficiency is prevalent when intake of these foods is low due to their high cost, lack of availability, or cultural or religious beliefs. Deficiency is certainly more prevalent in strict vegetarians, but lacto-ovo vegetarians are also at higher risk for inadequate intakes. If the mother is folate-depleted during lactation, breastmilk concentrations of the vitamin are maintained while the mother becomes more depleted. In contrast, vitamin B12 concentrations in breastmilk can be markedly lower in vitamin B12depleted women. The impact of gene polymorphisms on folate and vitamin B12 status and requirements in a population will vary depending on the underlying prevalence in that population. Although not well understood, gene polymorphisms almost certainly affect the risk of adverse pregnancy outcomes. Folic acid and vitamin B12 in synthetic form are absorbed at about twice the efficiency as the food forms, especially in lower doses. The consultation agreed on conclusions in four areas: » Indicators for assessing the prevalence of folate and vitamin B12 deficiencies » Health consequences of folate and vitamin B12 deficiencies » Approaches to monitoring the effectiveness of interventions » Strategies to improve intakes of folate and vitamin B12

Iodine Deficiency in the World: Where Do we Stand at the Turn of the Century?

Iodine deficiency is the leading cause of preventable mental retardation. Universal salt iodization (USI), calling for all salt used in agriculture, food processing, catering and household to be iodized, is the agreed strategy for achieving iodine sufficiency. This article reviews published information on programs for the sustainable elimination of the iodine deficiency disorders and reports new data on monitoring and impact of salt iodization programs at the population level. Currently, 68% of households from areas of the world with previous iodine deficiency have access to iodized salt, compared to less than 10% a decade ago. This great achievement, a public health success unprecedented in the field of noncommunicable diseases, must be better recognized by the health sector, including thyroidologists. On the other hand, the managers and sponsors of programs of iodized salt must appreciate the continuing need for greatly improved monitoring and quality control. For example, partnership evaluation of iodine nutrition using the ThyroMobil model in 35,223 schoolchildren at 378 sites of 28 countries has shown that many previously iodine deficient parts of the world now have median urinary iodine concentrations well above 300 microg/L, which is excessive and carries the risk of adverse health consequences. The elimination of iodine deficiency is within reach but major additional efforts are required to cover the whole population at risk and to ensure quality control and sustainability.

Current global iodine status and progress over the last decade towards the elimination of iodine deficiency

OBJECTIVE To estimate worldwide iodine nutrition and monitor country progress towards sustained elimination of iodine deficiency disorders. METHODS Cross-sectional data on urinary iodine (UI) and total goitre prevalence (TGP) in school-age children from 1993-2003 compiled in the WHO Global Database on Iodine Deficiency were analysed. The median UI was used to classify countries according to the public health significance of their iodine nutrition status. Estimates of the global and regional populations with insufficient iodine intake were based on the proportion of each countrys population with UI below 100 microg/l. TGP was computed for trend analysis over 10 years. FINDINGS UI data were available for 92.1% of the worlds school-age children. Iodine deficiency is still a public health problem in 54 countries. A total of 36.5% (285 million) school-age children were estimated to have an insufficient iodine intake, ranging from 10.1% in the WHO Region of the Americas to 59.9% in the European Region. Extrapolating this prevalence to the general population generated an estimate of nearly two billion individuals with insufficient iodine intake. Iodine intake was more than adequate, or excessive, in 29 countries. Global TGP in the general population was 15.8%. CONCLUSION Forty-three countries have reached optimal iodine nutrition. Strengthened UI monitoring is required to ensure that salt iodization is having the desired impact, to identify at-risk populations and to ensure sustainable prevention and control of iodine deficiency. Efforts to eliminate iodine deficiency should be maintained and expanded.

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 Childrens 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 populations zinc status.

Review of the magnitude of folate and vitamin B12 deficiencies worldwide.

Human deficiencies of folate and vitamin B12 result in adverse effects which may be of public health significance, but the magnitude of these deficiencies is unknown. Therefore, we examine the prevalence data currently available, assess global coverage of surveys, determine the frequency with which vitamin status assessment methods are used, and identify patterns of status related to geographical distribution and human development. Surveys were identified through PubMed and the Vitamin and Mineral Nutrition Information System at the World Health Organization (WHO). Since different thresholds were frequently used to define deficiency, measures of central tendency were used to compare blood vitamin concentrations among countries. The percentage of countries with at least one survey is highest in the WHO Regions of South-East Asia and Europe. Folate and vitamin B12 status were most frequently assessed in women of reproductive age (34 countries), and in all adults (27 countries), respectively. Folate status assessment surveys assessed plasma or serum concentrations (55%), erythrocyte folate concentrations (21%), or both (23%). Homocysteine was assessed in one-third of the surveys of folate and vitamin B12 status (31% and 34% respectively), while methylmalonic acid was assessed in fewer surveys of vitamin B12 status (13%). No relationship between vitamin concentrations and geographical distribution, level of development, or population groups could be identified, but nationally representative data were few. More representative data and more consistent use of thresholds to define deficiency are needed in order to assess whether folate and vitamin B12 deficiencies are a public health problem.

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 worlds 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.

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 </=20% of people. Some scientists felt this proportion was unacceptably high and wanted to increase the threshold above 100 micro g/l. The study was carried out to determine the frequency distribution of urinary iodine in iodine-replete populations (schoolchildren and adults) and the proportion of concentrations <50 micro g/l. METHOD A questionnaire on frequency distribution of urinary iodine in iodine-replete populations was circulated to 29 scientific groups. FINDINGS Nineteen groups reported data from 48 populations with median urinary iodine concentrations >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.

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

Micronutrient deficiencies (MNDs) contribute significantly to the worlds 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.