Two people hugging
Parents fret that Covid-19 has created a generation of lost children. This needs to be corrected (Alamy Stock Photo)

As Covid-19 spread across the world in 2020, millions of young people were taken out of school. Referred to as a “lost generation”, it is often assumed that these children will struggle, if not ultimately fail, to catch up on the days, weeks and months of education they could not access. The anxiety for themselves, their parents and their educators is animated by a fear that they have been damaged already, perhaps irreparably, and that their lives will be blighted forever.

But we know from the latest research into child and adolescent development that a young person’s ability to catch up should never be considered beyond reach. This doesn’t only hold true for education. Across the globe, “Catch Up” is a technical term applied to a much more fundamental process: the restoration of height, weight and cognition that has been lost as a result of malnutrition. We know from this process that young humans are extraordinarily resilient. With adequate care and support, they have a good chance of regaining what they have lost. It doesn’t take much, as long as an essential first ingredient is present: the knowledge that children can recover from setbacks.

The evolving science of nutrition

The science of nutrition is relatively new. The first vitamin, B1, was isolated and chemically defined in 1926. By the 1950s, all the remaining essential micronutrients had been identified and synthesised. It was a transformation in our understanding of malnutrition. Starving children weren’t just lacking food, they were missing these minuscule but essential micronutrients.

Those of us with the luxury to do so get our iron, iodine and Vitamin A – the three micronutrients that are vital preventatives of malnutrition – from the regular food we buy at supermarkets. They enable our bodies to produce enzymes, hormones and other chemicals, and thereby create the messaging system that actually tells our cells to grow or develop or change. It is micronutrients that make us what we will eventually become, but many around the world struggle to access them.

The best indication that micronutrients are absent from a child’s diet for long periods is stunting (when a child is too short for their age) and wasting (when a child is too thin for their age). A child may feel full from macronutrients (proteins, fats and carbohydrates), but if there are no micronutrients then their cells aren’t getting the messages to keep growing towards adulthood. So instead they go into a kind of cellular power conservation survival mode, ready for when the micronutrient going eventually gets better. This process is known as “thrifty growth”. The child’s energy is diverted towards basic survival: keeping their brain and lungs functioning optimally for as long as possible. Less energy, therefore, goes where it should, and their bones stop lengthening as a result.

But nothing can be thrifty for ever. Eventually energy runs out, and malnutrition starts to affect a child’s cognitive and behavioural development. Malnourished children have less energy to walk to school, and less ability to concentrate when they get there. It is therefore not only once-in-a-lifetime pandemics that keep children out of school; for many children living in conditions of war and famine, myriad factors combine to stop them from accessing education.

To date, the easiest way to restore micronutrients is to add them to what are called fortificant food premixes, or to provide them as concentrated supplements in the form of iodised salt, iron tablets and syrups, and Vitamin A capsules. But we are also taking our understanding of the role of micronutrients in new and wonderful directions. Through precise selective breeding, agri-nutritionists have created whole new families of potatoes and sweet potatoes that are “nutri-dense”, which means they grow with the highest possible pro-Vitamin A and enhanced iron content.

These crops aren’t only designed to combat malnutrition; they can also help us to meet the challenges of the climate crisis. Ensuring that what we grow has the maximum nutritional value will become increasingly important as the climate changes. This new class of vegetables is drought tolerant and doesn’t mind poor soil, which makes them easy to farm in the world’s increasingly hot and dry places, where children are already more likely to need micronutrient supplements.

No more thrifty growth

But correcting malnutrition is also a question of timing. Scientists often talk about “the first thousand days” of a child’s life as being the most important for interventions. All micronutrient supplements are best at generating Catch Up when the little human taking them is – or should be – undergoing a growth spurt. Supplements should therefore be given in the earliest years of life, when their cells should be fizzing with activity and potential. Across the world, studies show that malnourished children up to the age of three who receive micronutrient supplementation begin to grow again. Perhaps they won’t be quite as tall as the international height standard for their region, but nevertheless, they can be put onto the right track. And it means much more than merely taller children with longer legs. It means the messages generated by micronutrients are getting to the right places, stimulating the cell growth and development that are also needed for cognitive development. No more thrift. Children that have fallen behind catch up, both mentally and physically.

The “thousand days” window is extremely important. But we have recently begun to recognise that there is another crucial window of opportunity. Humans have two significant growth spurt periods in their life: one in the first thousand days; the other during adolescence, when puberty occurs. This second growth spurt is every bit as vital to our adult development as the first one. Humans get about 25 per cent of their eventual height during their teenage years, and like those first thousand days, we rely on the chemical messaging of the micronutrient system to get this rapid growth phase in our development done.

The need for energy and micronutrients will never be higher than it is in adolescence. This is the point when the micronutrients should be messaging the hormones to tell the brain to develop voluntary-control mechanisms and executive function: the means whereby people get to choose their behaviours, understand their choices, make plans and see them through. If the messages don’t get through, it isn’t just leg length that is profoundly limited. Cognitive development is every bit as likely as bone length to be stunted and eventually wasted.

Adolescents, however, don’t receive enough attention, despite the possibilities presented for their Catch Up. In fact, studies from across the world are starting to come in that show that when micronutrient supplementing measures are applied to malnourished adolescents, Catch Up happens much more quickly, significantly and observably than it does in the toddler cohort. Restoring the right amount of nutritious food to teenagers means they do what they are meant to do, and grow to become healthy adults.

So why don’t we see more programmes and funding directed at teenagers in need, particularly as such interventions are reasonably affordable? It seems that the science is being held back by our prejudices. It’s very difficult to fund science on adolescents because society is wary of vaguely threatening young male teenagers living in difficult places where conflict drives their hunger. Their rough skin and narrowed eyes, full of fear and aggression, don’t make for good photographs in funding applications. For no good reason, it is often assumed that it’s too late to restore what has been lost to these vulnerable young men who are no longer children but have become a frightening, potentially dangerous population. Instead, the round, tear-filled eyes of the hungry toddler, cradled in its mother’s arms, gets all the oxygen in the funding room, and most of the money.

This is a huge wasted opportunity – for girls as well as boys. Thus far, everything we know about the potential of adolescent Catch Up comes from studying groups in developed nations: young people who are malnourished for a range of reasons other than conflict or famine, including patients who are congenitally deficient in hormones, who have coeliac disease, or whose bones have been stunted by conditions such as cerebral palsy. Whatever the reason for what is technically termed “affluent stunting”, micronutrient restoration produces Catch Up in these adolescents, steadily and permanently.

It wouldn’t be difficult to adapt this research to create an infrastructure to enable adolescent Catch Up all over the non-affluent world, and it’s likely to result in better fed teenagers who make more thoughtful decisions about the rest of their lives. The Lancet’s launch in November of a series on adolescent nutrition, acknowledging that the field is “overlooked in policy and investment”, is a welcome development, but much more needs to be done. The essential first step, of course, would be accepting that these teenagers are worthy of the effort.

The fundamental value of nurture

There is another major area upon which we could improve, and that is prevention. Everyone agrees that prevention is better than cure. Ending world hunger would be excellent, but in the meantime what can be done to delay the point at which hunger becomes malnutrition and thrift becomes loss? The answer is perhaps unexpected, but even more hopeful than the progress with micronutrient-generated Catch Up. This is because it is something we already do well, across the world and relatively cheaply: we vaccinate.

Vaccinations are so very helpful in achieving Catch Up because malnutrition is not just about not enough good food. It also happens because our immune systems, for some evolutionary reason, are not part of the thrifty growth system. When a child’s physiology begins to conserve energy, the immune system is immediately diminished, leaving them vulnerable. So the hungry child gets infections everywhere, but especially in the gut, where they cascade catastrophically, starving the child from inside as well as out.

This quickly becomes a vicious cycle. Even when micronutrient levels are restored with supplements, the energy that should be resuming growth patterns stays fighting the effects of infection. The result: no Catch Up, just a slow diversion of resources into a cycle of hunger and sickness. In a vaccinated child, however, the chemical messages aren’t wasted fighting infections, but go where they are needed to generate positive growth and development.

Not only do vaccinations help break the malnutrition-immune dysfunction cycle, they also fill in the immunity gap. This is because vaccinations can generate what are technically called “beneficial non-specific effects”. It means that a BCG shot, for instance, given against TB or leprosy, also strengthens the whole immune response in each child that receives it, and therefore gives better overall resistance to disease. Another example is the measles vaccine, which gives the same fortificant power to the overall developing immune system, as well as no more measles.

Not all vaccinations have this ability. The pneumonia vaccine, for example, simply does what it says on the vial. And the BCG vaccination has to be given as early in the first thousand days as possible in order to achieve its best effects. If it’s done right, a vaccinated child has higher haemoglobin levels than an unvaccinated child and is therefore less likely to need iron supplements. This is because vaccinations have ensured that at least one of its micronutrients is doing just fine, getting the important messages to wherever in the body they are needed.

We don’t yet know if something similar happens with teenage vaccinations. But that’s only because we haven’t looked yet.

One more thing. When a child is taken for their vaccination, we can see a process at work that is as fundamental to achieving proper nutrition in its widest possible sense as feeding is. A vaccinated child is a nurtured child. If the child is held and comforted during the process, their tears wiped away and their paper record card carefully kept until next time, then they are receiving nurturing care. Nurturing generates cognitive stimulation, just as micronutrients do.

A child that isn’t nurtured isn’t only less likely to be vaccinated. If no one reads them a story at a regular bedtime or ensures they are warm, comfortable and able to dream their way through untroubled nights, then they may never be able to read a story all the way to the end for themselves. Even if they can walk to school they won’t be able to do much when they get there.

This holds for teenagers too. If no one listens to the aspirations of an adolescent, and if they aren’t encouraged to stay in school for as long as possible, then even if their bellies are full they too will be held back and eventually fall behind. Literacy is as a good marker as vaccination status as to whether or not a child or adolescent is receiving the essential ingredients of nurturing.

Healthcare by other means

Yet for all the work being done to increase vaccinations, and despite a 70 per cent drop worldwide in vaccine-preventable deaths since 2000, there are reckoned to be 20 million children who are under-vaccinated, which means they may have received no or only some of their vaccinations. It’s not because of funding shortages. Vaccines are efficient and inexpensive, and vaccinators are never short on energy and courage. But vaccinations stall in particular regions in the world because of political instability, poor communications and community dysfunction – for all sorts of reasons that don’t need more science for resolution, just better human activity and wider peace. In the meantime, the gap remains.

A good place to start bridging the gap would be through the sustainable development goals (SDGs) set by the UN for realisation in 2030. We should make a new goal, specifically aimed at optimising current vaccination strategy systems so that every young person may have an optimised immune system. That is a good place to start, because vaccinations are healthcare systems by other means, easy and cheap to establish. This new SDG could probably be brought in ahead of schedule because it only needs a bit more science, some improved communications and logistics and – perhaps the most significant challenge of all – for us to set aside our prejudices about who is deserving of our care and attention, of our best and most expensive research efforts. If we have two chances per human to optimise immune systems and therefore generate Catch Up, then we should take them both, and let no one fall behind.

There are no lost generations, just the ones we prefer not to see. Catch Up, wherever you look for it, depends on human beings doing things we already know how to do, and doing them as well as they can possibly be done for every single child and adolescent who needs them. Young people themselves – with their remarkable resilience and ability to survive – will do most of the rest, given just a little of the right support.

This piece is from the New Humanist spring 2022 edition. Subscribe here.