The World Health Organisation describes micronutrient deficiencies, or hidden hunger, as a form of malnutrition that occurs due to low intake and/or absorption of minerals and vitamins, putting human development and health at risk. In many cases, emphasis, effort, and even policy, revolves around the prevention of deficiency of one particular micronutrient in isolation. This is understandable as that micronutrient may be among a group of nutrients of public health concern. Vitamin D is a good exemplar. This review will highlight how the actions taken to tackle low vitamin D status have been highly dependent on the generation of new data and/or new approaches to analysis of existing data, to help develop the evidence-base, inform advice/guidelines, and in some cases, translate into policy. Beyond focus on individual micronutrients, there has also been increasing international attention around hidden hunger, or deficiencies of a range of micronutrients, which can exist unaccompanied by obvious clinical signs but can adversely affect human development and health. A widely quoted estimate of the global prevalence of hidden hunger is a staggering two billion people, but this is now over 30 years old. This review will outline how strategic data sharing and generation is seeking to address this key knowledge gap in relation to the true prevalence of hidden hunger in Europe, a key starting point towards defining sustainable and cost-effective, food-based strategies for its prevention. The availability of data on prevalence and food-based strategies can help inform public policy to eradicate micronutrient deficiency in Europe.

Micronutrient deficiency persists throughout the world, and although the burden is higher in low-resource settings, it is also prevalent in wealthy countries, a phenomenon termed ‘hidden hunger’. Due to their high requirements for vitamins and minerals relative to their energy intake, young women and children are particularly vulnerable to hidden hunger. As they share several risk factors and impact on overlapping outcomes, we consider how deficiency of iron, iodine and vitamin D can have profound impacts on perinatal health and infant development. We review the epidemiology of these micronutrient deficiencies during pregnancy, including social, environmental and dietary risk factors. We identify the main challenges in defining nutritional status of these nutrients using validated diagnostic criteria linked with meaningful clinical outcomes. Public health strategies are urgently required to improve the overall health and nutritional status of women of reproductive age. Obesity prevention and early detection of malnutrition with standardised screening methods would detect pregnant women at increased risk of iron deficiency. Development of sensitive, individual biomarkers of iodine status is required to protect maternal health and fetal/infant brain development. Risk assessments of vitamin D requirements during pregnancy need to be revisited from the perspective of fetal and neonatal requirements. International consensus on standardised approaches to micronutrient assessment, analysis and reporting as well as sensitive, clinically validated infant and child neuro-behavioural outcomes will enable progression of useful observational and intervention studies.

Selenium (Se) is an essential element for human health. However, our knowledge of the prevalence of Se deficiency is less than for other micronutrients of public health concern such as iodine, iron and zinc, especially in sub-Saharan Africa (SSA). Studies of food systems in SSA, in particular in Malawi, have revealed that human Se deficiency risks are widespread and influenced strongly by geography. Direct evidence of Se deficiency risks includes nationally representative data of Se concentrations in blood plasma and urine as population biomarkers of Se status. Long-range geospatial variation in Se deficiency risks has been linked to soil characteristics and their effects on the Se concentration of food crops. Selenium deficiency risks are also linked to socio-economic status including access to animal source foods. This review highlights the need for geospatially-resolved data on the movement of Se and other micronutrients in food systems which span agriculture–nutrition–health disciplinary domains (defined as a GeoNutrition approach). Given that similar drivers of deficiency risks for Se, and other micronutrients, are likely to occur in other countries in SSA and elsewhere, micronutrient surveillance programmes should be designed accordingly.

‘Hidden hunger’ is a term used to describe human deficiencies of key vitamins and minerals, also known as micronutrients. While global in scale, the prevalence of micronutrient deficiencies is particularly high in South Asia despite recent successes in economic growth, agricultural output and health care. The present paper reviews the most recent evidence on patterns and trends of hidden hunger across the region, with a focus on the most significant deficiencies – iodine, Fe, vitamin A and Zn – and interprets these in terms of health and economic consequences. The challenge for South Asian policy makers is to invest in actions that can cost-effectively resolve chronic nutrient gaps facing millions of households. Appropriate solutions are available today, so governments should build on evidence-based successes that combine targeted health system delivery of quality services with carefully designed multisector actions that help promote healthier diets, reduce poverty and ensure social protection simultaneously.

Hidden hunger occurs in the presence of an otherwise nutritionally or energetically appropriate diet that is deficient in essential vitamins and minerals. Guatemala has the highest rate of child malnutrition in Latin America and the prevalence of hidden hunger is high. The aim of this study was to determine the Mn, Se and Cr dietary intakes in Guatemalan institutionalised children (4–14 years), a population group at high risk of mineral deficiency. For this purpose, the contents of Mn, Se and Cr were analysed in a duplicate diet (for 7 consecutive days) by electrothermal atomisation-atomic absorption spectrophotometry following acid digestion. Mn, Se and Cr intakes from the duplicate diets were in the range of 1·3–2·31 mg/d, 58·7–69·6 µg/d and 6·32–27·57 µg/d, respectively. Mn and Cr values were below current recommended daily intakes. A cereal- and legumes-based diet is habitually consumed by this population. Local vegetables, fruits and nutritional supplements are included daily, but the consumption of fish, meat, eggs and dairy products is very infrequent or negligible. Mean daily energy intake from the 7-d diet was 8418·2 kJ (2012 kcal), with a macronutrient energy distribution of carbohydrates 69·4 %, proteins 12·3 % and fats 18·3 %. Correlations between Mn, Se and Cr intakes and energy and other nutrient intakes were also evaluated. The present findings will help establish new nutritional strategies for this and similar population groups.

Major advances have occurred in food production during the last 30 years as a result of the adoption of ‘green revolution’ technology. The price of rice and wheat is 40 % lower than it was in the 1950s. This lower price has helped the poorer sections of society, who spend 50–60 % of their income on food. The proportion of the population in the developing world that is malnourished fell from 46·5 % in the early 1960s to 31 % in 1995. However, there are still 1·3 billion of the population who go to bed hungry every day. Deficiencies of micronutrients such as Fe, Zn and vitamin A affect millions of the population in the developing world. The world population is increasing at the rate of 1·4 %, or an increase of eighty million per year. It is estimated that we will have to produce 50 % more food grains by 2025. Various strategies for meeting this challenge exist, including the development of cereal varieties with a higher yield potential and yield stability, and farmer-friendly public policies. In order to tackle hidden hunger, efforts are underway to develop crop varieties with higher concentrations of Fe and Zn. Recently, a breakthrough has occurred in the introduction of the genes for the pathway leading to the biosynthesis of β-carotene, a precursor of vitamin A, in rice. Various conventional approaches and modern tools of biotechnology are being employed in the development of crop varieties with higher yields and higher levels of micronutrients.