This paper estimates the global and regional prevalence of certain micronutrient deficiencies in two population groups that are particularly vulnerable to such deficiencies. By analysing 24 datasets, it estimates that, globally, around 56% of preschool-aged children are deficient in at least one of iron, zinc and vitamin A, and that 69% of non-pregnant women of reproductive age are deficient in at least one of iron, zinc and folate.
The results show that patterns of micronutrient deficiency vary around the world, and that large proportions of populations are affected by various deficiencies in both lower and higher income countries, as illustrated below. Among preschool-aged children, the estimated proportion experiencing a deficiency in iron, zinc or vitamin A ranges from 45% in high-income countries to 62% in Sub-Saharan Africa, compared to a global average of 56%. For non-pregnant women of reproductive age, the fraction experiencing a deficiency in iron, zinc or folate ranges from 48% in high-income countries to 80% in Sub-Saharan Africa, compared to a global average of 69%.
Image: Figure 1, Stevens et al. Prevalence of single or two or more micronutrient deficiencies in preschool-aged children aged 6–59 months (A) and non-pregnant women aged 15–49 years (B).
The study was based on datasets that measured biomarkers such as serum ferritin levels. The authors note that the finding of high rates of micronutrient deficiencies in high-income countries contrasts with previous work based instead on dietary intake, which found negligible rates of micronutrient inadequacy in food supplies. They call for future research to use both biomarkers and dietary intake to better understand the factors affecting micronutrient status.
Micronutrient deficiencies compromise immune systems, hinder child growth and development, and affect human potential worldwide. Yet, to our knowledge, the only existing estimate of the global prevalence of micronutrient deficiencies is from over 30 years ago and is based only on the prevalence of anaemia. We aimed to estimate the global and regional prevalence of deficiency in at least one of three micronutrients among preschool-aged children (aged 6–59 months) and non-pregnant women of reproductive age (aged 15–49 years).
In this pooled analysis, we reanalysed individual-level biomarker data for micronutrient status from nationally representative, population-based surveys. We used Bayesian hierarchical logistic regression to estimate the prevalence of deficiency in at least one of three micronutrients for preschool-aged children (iron, zinc, and vitamin A) and for non-pregnant women of reproductive age (iron, zinc, and folate), globally and in seven regions using 24 nationally representative surveys done between 2003 and 2019.
We estimated the global prevalence of deficiency in at least one of three micronutrients to be 56% (95% uncertainty interval [UI] 48–64) among preschool-aged children, and 69% (59–78) among non-pregnant women of reproductive age, equivalent to 372 million (95% UI 319–425) preschool-aged children and 1·2 billion (1·0–1·4) non-pregnant women of reproductive age. Regionally, three-quarters of preschool-aged children with micronutrient deficiencies live in south Asia (99 million, 95% UI 80–118), sub-Saharan Africa (98 million, 83–113), or east Asia and the Pacific (85 million, 61–110). Over half (57%) of non-pregnant women of reproductive age with micronutrient deficiencies live in east Asia and the Pacific (384 million, 279–470) or south Asia (307 million, 255–351).
We estimate that over half of preschool-aged children and two-thirds of non-pregnant women of reproductive age worldwide have micronutrient deficiencies. However, estimates are uncertain due to the scarcity of population-based micronutrient deficiency data.
US Agency for International Development.
Stevens, G.A., Beal, T., Mbuya, M.N., Luo, H., Neufeld, L.M., Addo, O.Y., Adu-Afarwuah, S., Alayón, S., Bhutta, Z., Brown, K.H. and Jefferds, M.E., 2022. Micronutrient deficiencies among preschool-aged children and women of reproductive age worldwide: a pooled analysis of individual-level data from population-representative surveys. The Lancet Global Health, 10(11), pp.e1590-e1599.