Can junk food be damaging children's skeletal development?

Credit: Maliz Ong/public domain

A team of researchers from the Hebrew University of Jerusalem has found a definite link between ultra-processed foods and reduced bone quality, unveiling the damage of these foods particularly for younger children in their developing years. The study was published in the journal Bone Research and serves as the first comprehensive study of the effect of widely-available food products on skeleton development.

Ultra-processed foods—aka junk food—are food items products that undergo several stages of processing and contain non-dietary ingredients (meaning additives that have no nutritional qualities). They’re popular with consumers because they are easily accessible, relatively inexpensive and ready to eat straight out of the package. They also often have a long shelf life as well. The increasing prevalence of these products around the world has directly contributed to increased obesity and other mental and metabolic impacts on consumers of all ages.

Children tend to like junk food. It’s been estimated that in some communities, as much as 70% percent of their caloric consumption comes from ultra-processed foods. While numerous studies have reflected on the overall negative impact of junk food, few have focused on its direct developmental effects on children, particularly young children.

The Hebrew University study provides the first comprehensive analysis for how these foods impact skeletal development. The study surveyed lab rodents and found that those that were subjected to ultra-processed foods suffered from growth retardation and their bone strength was adversely affected. Under close examination, the researchers detected high levels of cartilage build up in the rodents’ growth plates, the “engine” of bone growth. When subjected to additional tests it was found that the RNA genetic profiles of cartilage cells that had been subjected to junk food were showing characteristics of impaired bone development.

The team then sought to analyse how specific eating habits might impact bone development and replicated this kind of food intake for the rodents. The rodents’ weekly nutritional intake was divided – 30% came from a ‘controlled’ (healthy) diet, 70% from ultra-processed foods. These rodents experienced moderate damage to their bone density albeit there were fewer indications of cartilage build up in their growth plates. The research concluded that even in reduced amounts, the ultra-processed foods can have a definite negative impact on skeletal growth.

Carlos Monteiro is one of the world’s leading experts on nutrition and he is quoted as saying that there is no such thing as a healthy ultra-processed food. He is clearly right. It seems likely that even if the amount of fats, carbs nitrates and other known harmful substances are reduced, junk foods still possess their damaging attributes. Every part of the body is prone to this damage and certainly those systems that remain in the critical stages of development.

Some may criticise these findings, saying that the study was done on rats rather than humans. However, science continually finds merit in research conducted with rodents, because their genetic, biological and behaviour characteristics closely resemble those of humans, and many symptoms of human conditions can be replicated in mice and rats.

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Martin Doherty, writing for The Conversation, says that at the age of about four, children reach important milestones in brain development.

One of these is a huge improvement in understanding others’ thoughts and feelings. This is the start of empathy. Another is in spatial thinking—understanding how objects are positioned and related. This is the beginning of the ability to read maps.

Martin and his colleague, Catherine Sayer, conducted a study with 175 two to five-year-olds to explore how children are able to use scale models to figure out where something is in the real world. At about four, children are able to use a scale model of a room to work out where something is. We thought that this might result from children’s understanding of how one thing can represent something else. But we actually found that four-year-olds’ ability to use scale models came from their spatial abilities.

At the same age, children start to understand that someone’s behaviour is due to what that person believes, not necessarily what is really the case. This has interesting consequences.

If you’ve played hide-and-seek with young children, you may have noticed that they aren’t always very good at it. They love the ritual of looking in all the wrong places first, but beforehand they may tell you where they are going to hide, hide in the same place every time, or not be especially hidden.

After their fourth birthday, they get much better at hide and seek. They understand that the seeker looks in the wrong places because they don’t know where the hider is.

At about three to four children also start to tell lies. They realize they can make someone believe something that isn’t true.

Understanding symbols

Martin’s earlier research with fellow psychologist Josef Perner suggests that four-year-olds don’t just start to understand how others’ minds work. Figuring this out is part of the development of an understanding of “representation”—that symbols, like thoughts, words, or pictures, can be used to stand for something else.

Children start to think about how words relate to objects. This means, for instance, knowing that “animal” can refer to something you already have a name for, such as “rabbit”. This might help children learn the new word.

Their ability to use a understand the components of pictures also improves around this age. Very young children use a lot of trial and error to complete a jigsaw, picking up random pieces to see if they fit. By the time they are about four years old, they start to use the picture as a guide, trying to connect lines and match bits of colour, while checking the guide picture on the box lid.

Developmental experiments

Another ability children develop at around four is using scale models. A classic set of developmental experiments involved a model of a regular household room. The real room had typical furniture—sofa, table, cupboard and so on—and the model had miniature versions laid out in the same way.

Children were shown where something was hidden in the model and told to find an object hidden in “the same place” in the room. Children of around four can find the object using the identical layouts. If shown a sticker under a particular chair in the model room, for example, they can go straight to the “same” chair in the other room. This is the fundamental understanding required to read maps.

Adults see scale models and maps as representations. Maps represent a town or a country. A scale model of, say, the Eiffel Tower represents the real thing. At first, Martin suspected children’s ability to use scale models is more evidence of understanding representation at this age.

He was wrong. Instead, the researchers found that this ability is based on a development in children’s spatial abilities that also occurs at about four. This is the ability to think about spaces and where objects are within them. Spatial abilities help with maths skills, and good spatial ability is linked to an interest in science, technology, engineering and mathematics.

Their experiment was simple. They compared the model room task with a test of understanding how representation works. The two abilities develop around the same age, but they found they were not related. Children who could do one task couldn’t necessarily do the other.

They also had a test of purely spatial ability. Children who passed the model room task also passed the spatial task. So it looks like the model room task relied on children‘s spatial thinking.

They don’t yet know why two important but apparently unrelated abilities arise at the same time. Perhaps it’s related to changes in the growing brain at this interesting age.

Provided by The Conversation.

Image supplied by Freepik.