How Does A Poor Diet Affect A Child's Behaviour?

In this article, you’ll find:

• The importance of healthy eating for kids
• Benefits of healthy eating for children
• How does nutrition affect a child’s behaviour? 

If your child’s energy levels or mood are unpredictable, their diet might be playing a role. Many parents and caregivers may ask themselves: can a child's diet affect their behaviour?

The short answer is yes. Nutrition plays a key role in a child’s mental, physical and emotional wellbeing. In this article, we’ll be diving into the effects of diet on children’s behaviour, including how:

• Poor diet can impact a child's mood, energy, and concentration
• Processed foods may contribute to behavioural issues
• Low nutrient levels can affect brain development
• Healthy eating supports emotional regulation
• Food intolerances may trigger hyperactivity or irritability

Let’s take a closer look.

The importance of healthy eating for kids

Healthy eating during childhood can help lay the foundation for healthy growth and development. It’s about guiding kids toward nutritious, sustainable choices that support their long-term health and wellbeing¹.

As a parent or caregiver, you play a key role in guiding these habits. This often involves guiding them on healthy portion sizes, understanding the different food groups and prioritising balance when it comes to their diet². You have the opportunity to show your child the importance of healthy eating in early childhood and set positive habits for life.

As it turns out, healthy eating has several critical flow-on effects for growing bodies. A nutrient-rich diet can assist with your child’s physical and cognitive development, immune function and behavioural regulation^1,3. Rather than labelling foods as ‘good’ or ‘bad’, the focus should be on making healthy food choices by following practical advice.

What does a healthy diet look like for kids?

According to the Australian dietary guidelines, a healthy diet for children involves eating a wide variety of nutritious foods from the five food groups, while limiting the intake of saturated fats, added salts and added sugars^1,2,4.

Kids need a range of vitamins and minerals to support their growth, development and health⁵. Macronutrients, like carbohydrates, protein and healthy fats, provide children with a source of energy to help them get through the day⁵. Equally important are micronutrients, such as iron, zinc, vitamin C, B vitamins and omega-3, which support the countless biochemical processes happening in growing bodies⁶.

Benefits of healthy eating for children

Healthy eating in early childhood may support positive behavioural and developmental outcomes, including attention span, sleep quality, emotional stability and school readiness^1,7,8. A balanced diet fuels your child with the energy they need to stay active and focused during the day, while also helping to support consistent, restful sleep⁷. But nutrition isn’t just about physical health. The food kids eat also shapes their mood, mental health and ability to learn⁸.

Helping your child reach their recommended daily intake of vitamins and minerals can be tricky, especially if you’ve got a picky eater on your hands. That said, kids’ supplements can help to fill nutritional gaps⁵. But remember, supplements shouldn’t be used as a replacement for real food. Instead, supporting your child’s development starts with balanced nutrition. Stick to the Australian Guide to Healthy Eating to make sure they’re getting the right number of serves from all five food groups¹. 

How does nutrition affect children's behaviour?

So, what impact can a poor diet have on a child's behaviour? As it turns out, there’s a close link between nutrition and behaviour^3,9. Research has found that poor nutrition can be linked to mood swings, fatigue and hyperactivity⁹. In particular, low levels of certain nutrients, including iron, B12, iodine, and omega-3s, have been linked to irritability, fatigue, mood swings and impaired concentration. 

Is there a link between malnutrition and development?

Malnutrition refers to both over- and under-nourishment. Overnourishment is often the result of a diet that’s high in processed foods and added sugars, which may lead to an imbalance of nutrients despite a high caloric intake³. 

When children miss out on key nutrients like iron, iodine and B12, it can have a lasting impact. These nutrient gaps may affect their brain development, influence behaviour and increase their risk of long-term health issues³.

Can food intolerance cause behavioural issues in children?

Yes, for some children, food intolerances (e.g. dairy, gluten, salicylates, artificial colours) may affect mood and energy¹⁰. In saying that, it’s important to understand that food intolerances are different from food allergies. Although the two are often confused, they affect the body in different ways. 

Food allergies involve an immune response, and in some cases, can cause severe allergic reactions like anaphylaxis. Food tolerances, on the other hand, result in a chemical reaction, like asthma, fatigue or stomach upset¹¹. If you think your child may be allergic or intolerant to a food, consult your GP or a paediatric dietitian for a professional diagnosis and management plan.

A healthy diet can provide the nutrition your child needs for their cognitive and physical development^1,7,8. That said, ensuring your child eats a nutritionally balanced diet is often easier said than done. But remember, improving nutrition doesn’t require perfection, just informed, consistent choices. And if you’re unsure, be sure to speak to a paediatrician or your general health practitioner for professional and tailored advice.  

Check out the Swisse Wellness Hub for more information and advice on supporting your child’s nutritional needs.  

References:

1. NSW Government (2024). Healthy eating for children. [online] The Sydney Children’s Hospitals Network. Available at: https://www.schn.health.nsw.gov.au/kids-health-hub/kids-nutrition/healthy-eating-children.
2. National Health and Medical Research Council (2013). Healthy eating for children. [online] Available at: https://www.eatforhealth.gov.au/sites/default/files/files/the_guidelines/n55f_children_brochure.pdf.
3. The Royal Children's Hospital Melbourne (2019). Kids Health Info: Nutrition – school-age to Adolescence. [online] The Royal Children’s Hospital Melbourne. Available at: https://www.rch.org.au/kidsinfo/fact_sheets/Nutrition_older_children/.
4. Health Direct (2024). Healthy eating for children. [online] Healthdirect.gov.au. Available at: https://www.healthdirect.gov.au/healthy-eating-for-children.
5. Raising Children Network (2023). Vitamins and minerals. [online] Raising Children Network. Available at: https://raisingchildren.net.au/teens/healthy-lifestyle/nutrients/vitamins-minerals.
6. Faizan, U. and Rouster, A.S. (2023). Nutrition and Hydration Requirements In Children and Adults. [online] PubMed. Available at: https://www.ncbi.nlm.nih.gov/books/NBK562207/. 
7. NSW Government (2024). Sleep hygiene for kids | The Sydney Children’s Hospitals Network. [online] www.schn.health.nsw.gov.au. Available at: https://www.schn.health.nsw.gov.au/kids-health-hub/healthy-sleep-children/sleep-hygiene-kids.
8. Healthy Eating Advisory Service (2024). Food, mood & learning outcomes. [online] Healthy Eating Advisory Service. Available at: https://heas.health.vic.gov.au/resources/promoting-healthy-eating/food-mood-learning-outcomes/. 
9. British Dietetic Association (2020). Diet, behaviour and learning in children. [online] www.bda.uk.com. Available at: https://www.bda.uk.com/resource/diet-behaviour-and-learning-children.html.
10. St Joseph's Family Services (2022). Food Intolerances And Preschoolers - St Joseph’s Family Services. [online] St Joseph’s Family Services. Available at: https://sjfs.org.au/food-intolerance-in-preschoolers/.
11. Better Health Channel (2022). Food Allergy and Intolerance. [online] Better Health Channel. Available at: https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/food-allergy-and-intolerance.