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#CountryLevelZincData

New estimate of the global prevalence of hidden hunger - what does it say about zinc?

New estimate of the global prevalence of hidden hunger - what does it say about zinc?

Newly published research indicates that 1 in 2 children under the age of five and 2 in 3 women aged 15-49 are affected by micronutrient deficiencies globally.  This is equivalent to 372 million preschool children and 1.2 billion women. With these two population groups making up only one-third of the population worldwide, the total number of affected people is likely to be far larger once school-age children, adolescents, men and older adults are included in the estimate.

For over three decades it has been stated that micronutrients affect 2 billion people globally. However, this estimate has been based on the number of people with anemia, which is not equivalent to deficiencies in iron, zinc, folate, vitamin A, and other essential micronutrients.  A global prevalence estimate based on individual-level biomarker data has been desperately needed.

With funding from USAID, the Global Micronutrient Deficiencies Research Group led by the Global Alliance for Improved Nutrition (GAIN) pooled and re-analyzed individual-level biomarker data on micronutrient status from nationally representative, population-based surveys to estimate the prevalence and number of preschool children (6–59 months) and non-pregnant women of reproductive age (15–49 years) with one or more micronutrient deficiencies, globally and regionally.

The analysis included 24 datasets from nationally representative surveys in 22 countries. Zinc was selected as one of three core micronutrients together with iron and vitamin A for preschool children, and iron and folate for women. Data on plasma/serum zinc concentrations in PSC and WRA were available in 16 and 15 datasets, respectively. Among preschool children, the prevalence of zinc deficiency was ≥20% (the cutoff used to indicate a public health problem) in 12 datasets, and 10–19% in 4 datasets.  Among women, the prevalence of zinc deficiency was ≥20% in the 13 datasets from LMICs, 14% in United States and 10% in United Kingdom.  The countries with the highest prevalence of zinc deficiency (>50%) among both population groups were Cambodia, Cameroon, Malawi and Vietnam, as well as Ecuador for women.

The dearth of micronutrient biomarker data has been well-recognized and several recommendations to address this problem have been published. Along with the authors of these new global estimates, IZiNCG hopes the results of this analysis highlight the need for more and improved data on micronutrient status, increased funding for programs to implement and scale-up interventions to prevent micronutrient deficiencies, and improved monitoring and evaluation of such programs. 

Photo credit: World Bank photo collection

The India CNNS: A monumental survey identifying those at most risk of zinc deficiency

The India CNNS: A monumental survey identifying those at most risk of zinc deficiency

India’s 2016-2018 Comprehensive National Nutrition Survey (CNNS) is a truly admirable undertaking, as it is one of the largest micronutrient surveys ever conducted. This month, full results of the serum zinc status of children and adolescents were published in the American Journal of Clinical Nutrition with an accompanying editorial

Serum zinc concentrations (SZC) were assessed in more than 28,000 pre-schoolers, school aged children, and adolescents. Nationally, the prevalence of low SZC was 31.1% among adolescents, 15.8% among school-aged children and 17.4% among preschool children. State-level prevalence estimates ranged from 2.4% in Mizoram to 38.8% in Himachal Pradesh, using data for pre-school children as an example.  By providing much-needed data on zinc status at the national- and state- levels, the CNNS highlights the importance of biochemical data on micronutrient status to guide the targeting of interventions to the most vulnerable populations.  

It is helpful to start with what these prevalence estimates actually mean. India is the second most populous country in the world. While the prevalence of low SZC among children and adolescents may be lower in comparison to most of the 26 other low- and middle-income countries with available data on SZC, the CNNS findings indicate that approximately 38 million Indian children and 71 million Indian adolescents have an elevated risk of zinc deficiency. Those are staggering numbers.

It is important for individual governments to decide upon criteria to define national public health problems given a variety of contextual factors.  However, IZiNCG considers the risk of zinc deficiency to be of public health concern when the prevalence of low SZC is higher than 20%. This means that, at 31.1%, the prevalence of low SZC among adolescents calls for further investigation and action, particularly considering the intergenerational cycle of undernutrition and the fact that many girls who are zinc-deficient in adolescence will likely continue to be zinc-deficient during pregnancy in the absence of any intervention.   

Although the national prevalence estimates for zinc deficiency among pre-school and school-aged children were below 20%, state-level analyses revealed that the prevalence of zinc deficiency among preschool and school-aged children exceeded the 20% threshold in 10 out of 30 and 8 out of 30 states, respectively.  

Drilling down further, the results show that low SZC was more common among preschool children with rural residence, mothers with lower levels of education, and poorer household socioeconomic status and sanitation facilities. These findings identify vulnerable subgroups that should be prioritized to receive zinc interventions through existing platforms such as the Public Distribution System, Mid-day Meal program, and the Integrated Child Development Services, as well as new delivery channels.

An excellent review of the survey’s methods can be found in the editorial by Brown et al. As these authors note, no external quality assessments were reported for the laboratory assessment of SZC, which highlights the need for an easily accessible, global laboratory standardization program for SZC analysis.

In summary, the government of India is to be commended for undertaking such a monumental survey and generating the data needed to guide future interventions. The next challenge is to develop programs to address zinc and other micronutrient deficiencies in populations most in need.

Inclusion of Micronutrient Biomarkers in National Surveys and Surveillance Systems: Barriers and Enablers

Inclusion of Micronutrient Biomarkers in National Surveys and Surveillance Systems: Barriers and Enablers

IZiNCG is pleased to share the report Inclusion of Micronutrient Biomarkers in National Surveys and Surveillance Systems: Barriers and Enablers. This work was conducted with the support of the Micronutrient Forum.

Including biomarkers of micronutrient status in existing or planned national surveys or surveillance systems would dramatically improve capacity to promote, design, monitor and evaluate micronutrient policies and programs. Ultimately, investing in better data would yield healthier populations, safer programs and cost savings. 

Yet, the availability of nationally representative micronutrient biomarker data in low- and middle income countries (LMICs) is scarce. Taking plasma/serum zinc concentrations among pre-school children as an example, only 26 LMICs have published data.

“Micronutrient deficiencies are estimated to impact a significant number of people around the world, but there remains far too little information on micronutrient status and deficiencies. More essential information and surveillance need to be gathered to make substantial progress on global targets.” 

Global Nutrition Report 2018

The objectives of this study were to identify barriers to, and enablers of, the inclusion of micronutrient biomarkers in national surveys and surveillance systems. IZiNCG conducted a series of key informant interviews with in-country and external representatives from six countries where national-level data on micronutrient status had been collected in the past five years: Cambodia, Pakistan, Malawi, Uganda, Ghana and Uzbekistan.

The most important and frequently reported barrier to inclusion of a more comprehensive panel of micronutrient biomarkers was inadequate funding to cover the analysis cost for all micronutrients considered at the planning stage. Government support and commitment was stressed as the most important enabling factor by all key informants. For the findings in full, please read the report here.

What can be done to address the barriers identified in the report, and see more countries including micronutrient biomarkers in national surveys? This project is part of a wider collaborative effort led by the Micronutrient Forum aimed at increasing the availability and utilization of high-quality data on micronutrient status at the national/sub-national levels in LMICs. Read more in this recent publication.

Last updated: June 9, 2021

IZiNCG Symposium at Micronutrient Forum 5th Global Conference March 2020

IZiNCG Symposium at Micronutrient Forum 5th Global Conference March 2020

The Micronutrient Forum 5th Annual Conference will be held in Bangkok from March 23rd to 27th 2020. The theme is Building new Evidence and Alliances for Improving Nutrition, and our colleagues at the Micronutrient Forum are promising their best conference yet!

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If you are going to Bangkok, please mark Wednesday March 25th from 12.30 to 2pm in your calendar now for IZiNCG’s Symposium titled Advancing Efforts to Improve Zinc Nutrition Globally. We will present on recent developments and opportunities for action in assessment of zinc status, advances in the delivery of additional zinc to vulnerable populations, and progress in the use of therapeutic zinc as part of diarrhoea treatment. One of the presentations will share preliminary findings from the Zinc in Powders Trial, where data collection is on track to finish by January 30, 2020.

See you there?

Update: The Micronutrient Forum 5th Annual Conference has been postponed and will now take place between November 8-13, 2020.

Case study: Addressing Zinc Deficiency Through Wheat Flour Fortification in Cameroon

Case study: Addressing Zinc Deficiency Through Wheat Flour Fortification in Cameroon

As part of a series of case-studies on population-level zinc interventions, Ann Tarini (Independent Consultant), Ismael Teta, Alex Ndjebayi and Jules Guintang Assiene (Helen Keller International, Cameroon) and Reina Engle-Stone (UC Davis) have summarised the Cameroon experience of implementing wheat flour fortification to address zinc deficiency in a new IZiNCG brief.

Food fortification is one of three main strategies to address zinc deficiency in a population. This six page brief covers key program milestones, the rationale for wheat flour fortification, early program impact, a commentary on sustainability, and key lessons learned.

But perhaps most importantly, it highlights the power of data. Prior to 2009, no information was available on the status of zinc and several other micronutrients in Cameroon. In 2009, the Ministry of Public Health conducted a National Micronutrient Survey; the availability of data on plasma zinc concentration enabled the identification of zinc deficiency as a public health problem, and dietary intake data helped identify possible fortification vehicles along with their potential impact. The measurement of plasma zinc concentrations in the two major urban centers in 2012 enabled inference about program impact. And without monitoring data, it would not have been possible to identify and address the faltering of the program in 2016.

We hope Cameroon’s experience can provide inspiration and guidance to other countries considering zinc fortification.

Related:

IZiNCG Research Projects: Zinc Fortification Task Force

IZiNCG Technical Brief no. 4: Zinc Fortification

IZiNCG Technical Document no. 2

Estimating national risk of zinc deficiency: proxy indicators vs. plasma/serum zinc concentrations

Estimating national risk of zinc deficiency: proxy indicators vs. plasma/serum zinc concentrations

There is an urgent need for more and better data on the zinc status of vulnerable populations to effectively target and monitor zinc intervention programs.

Plasma/serum zinc concentration is endorsed as the best available biomarker of zinc status, particularly for assessing the risk of zinc deficiency in target population groups such as preschool-aged children and women of reproductive age. Given the scarcity of nationally representative PZC data, global estimates for the risk of zinc deficiency have been based on two proxy measures:

  • the amount of absorbable zinc in the national food supply, and

  • the prevalence of stunting among children under five.

The risk of zinc deficiency is considered to be elevated and a likely public health problem when the prevalence of inadequate absorbable zinc intakes is >25% and if stunting rates are >20%.

National risk of zinc deficiency based on the prevalence of childhood stunting and the estimated prevalence of inadequate zinc intake (Wessells & Brown, 2012)

National risk of zinc deficiency based on the prevalence of childhood stunting and the estimated prevalence of inadequate zinc intake (Wessells & Brown, 2012)

Wessells & Brown estimated the global prevalence of zinc deficiency:

  • Based on the Food and Agriculture Organization of the United Nations’ (FAO) Food Balance Sheets, at least 17% of the world’s population is at risk of inadequate zinc intake.

  • In 2011, 84 low-and middle-income countries (LMICs) with available data had a stunting prevalence >20% among children <5 years of age. Furthermore, 32 of these countries were identified as high risk based on both dietary intake and stunting.

However, comparisons with data from national surveys that have measured plasma or serum zinc concentration show that intake based on food balance sheets underestimate the risk of zinc deficiency. As seen in the map below, the prevalence of low plasma/serum zinc concentrations in young children was >20% in the majority of the surveys.

Percentage of pre-school children with low plasma or serum zinc concentrations. Map generated from data in the World Health Organization’s Vitamin and Mineral Nutrition Information System Micronutrients Database.

Percentage of pre-school children with low plasma or serum zinc concentrations. Map generated from data in the World Health Organization’s Vitamin and Mineral Nutrition Information System Micronutrients Database.

Countries with population-level data on plasma/serum zinc concentrations

Countries with population-level data on plasma/serum zinc concentrations

IZiNCG keeps a global inventory of recently completed and upcoming national nutrition surveys in low- and middle income countries where plasma/serum zinc concentrations have been assessed. Countries for which published reports are available are listed below.

In 2018, plasma/serum zinc was incorporated into WHO’s Micronutrient Database, which enables data visualization. Two publications have summarized available nationally-representative data on plasma/serum zinc concentrations: Hess 2017 and Gupta et al 2020.

Last updated: 10 November 2022

Afghanistan — National Nutrition Survey Afghanistan (2013) Survey Report
Azerbaijan — Nutrition Survey 2013 
Bangladesh — National Micronutrients Status Survey 2011-12 – Final Report
Cambodia — The High Prevalence of Anemia in Cambodian Children and Women Cannot Be Satisfactorily Explained by Nutritional Deficiencies or Hemoglobin Disorders
Cameroon — Stunting Prevalence, Plasma Zinc Concentrations, and Dietary Zinc Intakes in a Nationally Representative Sample Suggest a High Risk of Zinc Deficiency among Women and Young Children in Cameroon
China — survey data (2013) for children 36-72 months available in National Risk of Zinc Deficiency as Estimated by National Surveys
Colombia — Factores asociados a la deficiencia de zinc en niños colombianos; resultados de la Encuesta Nacional de Salud 2010; estudio transversal 
Costa Rica
Encuesta Nacional de Nutrición 2008-2009
Equador
Encuesta Nacional de Salud y Nutrición (ENSANUT-ECU) 2011-2013
Ethiopia — Ethiopian National Micronutrient Survey Report, September 2016
Fiji   2014 – 2015 National Nutrition Survey (available on request)
Guatemala — Encuesta Nacional de Micronutrientes 2009-2010; SIVESNU 2016
India — Comprehensive National Nutrition Survey: 2016-2018; Prevalence of low serum zinc concentrations in Indian children and adolescents: findings from the Comprehensive National Nutrition Survey 2016–18
Iran
Second National Integrated Micronutrient Survey in Iran: Study Design and Preliminary Findings
Jordan
 — Jordan National Micronutrient and Nutrition Survey 2019
Kenya —  The Kenya National Micronutrient Survey 2011
Malawi — Malawi Micronutrient Survey Key Indicators Report 2015-16
Maldives — Project Report National Micronutrient Survey 2007 Republic of Maldives
Mexico — Anemia and iron, zinc, copper and magnesium deficiency in Mexican adolescents: National Health and Nutrition Survey 2006 ; Prevalence of Zinc Deficiency in Mexican Children and Women of Childbearing Age (abstract);  Iron, zinc, copper and magnesium nutritional status in Mexican children aged 1 to 11 years ; Iron, zinc, copper and magnesium deficiencies in Mexican adults from the National Health and Nutrition Survey 2006
Myanmar —Myanmar Micronutrient and Food Consumption Survey MMFCS (2017-2018) Interim Report (Feb 2019)
Nepal — Nepal National Micronutrient Status Survey
Nigeria — Nigeria Food Consumption and Nutrition Survey 2001-2003: Summary
Pakistan — Pakistan National Nutrition Survey 2018 - key findings report
Philippines  8th National Nutrition Survey: Philippine Nutrition Facts and Figures 2013: Biochemical Survey
Senegal — Statut en Zinc des Enfants Senegalais et Evaluation de L’Utilisation de la Concentration Plasmatique en Zinc pour Tester L’Impact des Programmes de Fortification ; Adjusting Plasma Concentrations of Ferritin, Retinol, and Zinc Affect the Prevalence of Micronutrient Deficiencies in Children but Not in Women (abstract)
Somalia  Somalia micronutrient survey 2019 (capillary blood zinc concentrations)
South Africa — National Food Consumption Survey-Fortification Baseline (NFCS-FB-I): South Africa, 2005
Sri Lanka — National Nutrition and Micronutrient Survey – Part II: Iron, Zinc and Calcium Deficiency Among Children Aged 6-59 Months
Timor Leste Timor-Leste Food and Nutrition Survey 2013- Final Report
Vietnam — Micronutrient Deficits Are Still Public Health Issues among Women and Young Children in Vietnam +new data coming