A new study shows that more than half of all preschool-aged children and two-thirds of women under 50 around the world suffer from deficiencies of critical micronutrients in their diets that result in physical and cognitive underdevelopment and hold back economic growth.

For the 20 million people who go to bed hungry every night in South Africa, according to SA Harvest, the physically painful gnawing of chronic hunger is all-consuming — how could it not be? But adding to the widespread problem of sheer lack of food is the less obvious blight of “hidden hunger”, the more descriptive term for micronutrient deficiency, which affects millions more.

Globally, the numbers are staggering. Four billion is the number of people newly estimated to have “hidden hunger” — deficiencies of critical micronutrients such as iron, zinc, vitamin A — caused by what they are, or are not, eating.

The study, titled Micronutrient Deficiencies Among Preschool-Aged Children and Women of Reproductive Age Worldwide, is based on findings from 22 countries. It shows that half of all preschool-aged children and two-thirds of women under 50 suffer from deficiencies of critical micronutrients in their diets that result in physical and cognitive underdevelopment, and hold back economic growth.

Africa hardest hit

The term “hidden hunger” came into use because micronutrient deficiencies are not well quantified, the report says. This is because most of them go undiagnosed because symptoms are non-specific and unclear.

“Hidden hunger is likely to affect nearly half the people on the planet, not a quarter as we had complacently assumed,” said Lawrence Haddad, executive director of the Geneva-based Global Alliance for Improved Nutrition (GAIN), which collaborated with a global team of micronutrient experts on the report.

The consequences are dire — both at an individual and population level.

“Our failure to nourish the youngest will undermine public health and haunt us socially, economically, environmentally and politically down the generations,” Haddad said.

The report says 56% of children under five are deficient in at least one of three micronutrients (iron, zinc and vitamin A), and 69% of “non-pregnant women of reproductive age” (ages 15 to 49) are deficient in at least one of iron, zinc and folate.

The new estimate of global “hidden hunger” is based on these rates and comes after 30 years of reliance on estimates based only on iron deficiency-related anaemia.

Different micronutrient deficiencies can cause birth defects, impaired brain development and function, reduced growth, increased susceptibility to infections, bone-, skin- and eye-health problems, as well as reduced school or work performance.

Vitamin A and zinc play a role in immune system function, while iron and B vitamins are critical for the production of healthy red blood cells and folate helps prevent birth defects.

How the new estimate was reached

The report estimated the burden of micronutrient deficiencies using six “sentinel” essential micronutrients (iron, vitamin A, zinc, vitamin B12, folate and vitamin D) from the 29 that are known.

The researchers re-analysed population-based national surveys from 22 countries, focusing on children under five and women under 50 because there was more data available on these groups. There was not enough comprehensive micronutrient-related data available for school-age children, adolescents, men and older adults, the authors said.

Overall, their re-analysis showed that one in every two people suffers from at least one micronutrient deficiency, with the problem most severe in sub-Saharan Africa and parts of Asia, in low-income and lower-middle income countries where most people eat mostly starchy staples such as maize, rice or wheat.

South Africa was not one of the countries included in the 22 countries whose population-based surveys were used as the basis for the new report, probably because of a lack of data. According to the University of Cape Town’s Children’s Institute, data on the prevalence of micronutrient deficiencies is not regularly collected at national and regional levels.

The 2016 South African Demographic Health Survey, however, classified almost two-thirds (61%) of children under five as anaemic.

In several countries in sub-Saharan Africa and South Asia, the report says, nine in 10 women have at least one micronutrient deficiency. In sub-Saharan Africa specifically, almost two-thirds (62%) of children under five and more than three-quarters (80%) of women aged 15 to 49 have at least one deficiency.

It’s not only a poverty problem

Even in the presence of enough food, around half the world’s population suffers from micronutrient deficiency. Half of the world’s children are not eating enough nutritious foods such as whole grains, fresh fruits, vegetables, dairy and fish.

The missing micronutrients would come from foods such as beans, peas and lentils, dark green leafy vegetables, eggs, dairy, unprocessed red meat and small oily fish.

In low- and middle-income countries, these foods are missing from most people’s diets mainly because they are unavailable, unaffordable or somehow inaccessible.

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But hidden hunger also exists in affluent societies, at surprisingly high levels, where obesity is common.

In high-income countries, huge proportions of women — one in three women in the United States and one in two women in the United Kingdom — suffer from one or more micronutrient deficiencies.

This is most likely because of the high consumption of ultra-processed foods (about 50% to 60% of daily energy intake, in both countries). These foods have been stripped of micronutrients in the journey from, for example, wholewheat grains to prepackaged, industrially produced biscuits.

The reason for the massive scale of the problem, the experts say, is a global food system that has become increasingly focused on monocultures, cultivating just a few main crops and animals as food sources for higher yields. These are then processed to make prepackaged foods that are stripped of most of their original nutritious qualities.

There are solutions…

Yet the world does have “readily available, impactful and low-cost solutions to tackle this”, said Saskia Osendarp, executive director of the Micronutrient Forum at the report’s hybrid launch (online and in The Hague, Netherlands) on 17 October.

Transforming food systems is no small thing, but it is key to solving micronutrient deficiency, as well as to limiting climate change (food is responsible for one-third of all global greenhouse-gas emissions) and curbing the relentless rise of non-communicable diseases, such as diabetes, stroke and heart disease.

On 7 December, Ty Beal, a researcher at GAIN, presented the new micronutrient research in Tokyo at the International Congress of Nutrition 2022, calling for the need to “incentivise production of micronutrient-rich foods, support local and national food businesses that produce these foods, strengthen nutritious food markets, improve the affordability and generate demand for nutritious foods”.

In addition, the report’s researchers say, specific actions to target micronutrient content in what we grow and what we eat are critical. They suggest three main ways to do this:

• Food fortification – that is, adding essential vitamins and minerals to widely consumed foods such as cereal flours, cooking oil and other condiments, for example, iodine added to salt.
• Biofortification increases the nutrient content of crops (wheat, rice, beans, maize) as they are growing through laboratory and agricultural methods.
• Supplementation that targets pregnant women and young children, using tablets, drops or similar, with additional doses of vitamin A, iron, folic acid and other micronutrients.

How did we slip so far behind?

How has it happened that, until Covid-19, the world had made relatively good progress in reducing hunger at a global level but not enough progress in what appears to be a fairly basic gap in nutrition?

Given the 30-year-old estimate of two billion people with micronutrient deficiency, globally we started with a high bar. Since then, the Micronutrient Forum’s Osendarp said, elevated carbon dioxide levels due to greenhouse-gas emissions have reduced crop yields and micronutrient content in foods.

More recently, “an accumulation of crises has further weakened global food systems — Covid, climate change, conflicts — and has led to a surge in the number of people with micronutrient deficiencies because they can no longer afford nutritious diets rich in micronutrients”.

Osendarp’s comments illustrate how micronutrient deficiency, while a serious global problem in its own right, is also just one symptom of the complex ways in which global food systems now work, and work against human and planetary health.

“We have not invested enough yet into these integrated, holistic approaches across food, health and social protection systems that are needed,” Osendarp said. “But our hope is that this publication is a game changer where micronutrient security is part of our approach to building more sustainable systems.” DM/MC