Nutrition – school-age to adolescence

  • All children and adolescents need healthy snacks and meals to support their growth and development.  A nutrient-rich diet plays an important role in your child’s mental and physical development.

    Unfortunately, nutritional deficiencies can occur in children when their diets include an excess of foods that are high in fat, sugar and salt. These are often in the form of treats (chips, chocolates, lollies, soft drink) or in food that has been processed (such as take-away food). Children who don’t eat a varied diet that includes enough fresh and whole foods risk long-term health consequences.

    A healthy diet with the right nutrition also plays a vital role in maintaining a healthy weight in children and adolescents. Eating patterns established in childhood continue into adulthood, so the more healthy choices children are offered, the better.

    Signs and symptoms of a poor diet

    Symptoms of poor diet can include:

    • being underweight, overweight or obese
    • constipation or changes in bowel habits
    • being pale or lethargic
    • tooth decay
    • poor physical growth.

    In some children, poor diet may be associated with:

    • behavioural problems
    • sleep issues
    • problems with emotional and psychological development
    • poor concentration or difficulties at school.

    What causes nutrient deficiency?

    Nutrient deficiencies may occur in children who do not eat a balanced diet, which often results in inadequate intake of fibre, vitamins and minerals. Some common problems that affect a healthy diet in children and adolescents include:

    Not enough fruits and vegetables

    Fibre keeps the digestive and immune systems healthy. A lack of whole fruits and vegetables and whole grains in the diet can mean children and adolescents don’t get enough fibre. Low-fibre diets can cause constipation, and put children at greater risk of developing bowel cancers and heart disease later in life. Having adequate amounts of fibre in the diet can be protective against excess weight gain and type 2 diabetes.

    Fruits and vegetables are also a good source of Vitamin C, which is needed by the body to assist with iron absorption, fighting infection and wound healing.

    Choosing a variety of different coloured whole fruits and vegetables (yellow, red and green) and including these as part of your child’s normal diet can help prevent problems associated with nutrient deficiencies.

    • Aim for 5 serves of grains (e.g. brown bread, pasta and rice), 5 serves of vegetables and 2 serves of fruit each day. Read more on number of serves here.
    • Fresh fruit and vegetables are best, but canned (in natural juice, drained) or frozen varieties are also good options and generally contain the same amount of nutrients as fresh. Dried fruit is nutritious, but has a high amount of natural sugar so should be eaten less frequently.

    Allergies and intolerances

    Children or adolescents who have been diagnosed with food allergy or intolerances should have their diet modified or supervised by a dietitian to ensure they get the nutrients required for healthy growth and development.

    Allergies to particular foods or food intolerances (e.g. lactose or gluten) can result in a limited diet and nutrient deficiencies if changes are not managed safely.

    • Lactose intolerance can lead to a decreased calcium intake – make sure your child has an alternative (e.g. lactose-free cow’s milk or yoghurt or calcium-fortified dairy alternatives).
    • Coeliac disease can lead to inadequate intake of fibre and increases the risk of iron deficiency due to gut inflammation – make sure your child has adequate iron-rich foods in their diet, such as red meat and leafy green vegetables.
    • Restriction of FODMAP containing foods can result in inadequate consumption of fibre and other important nutrients.

    Independent food choices and restricted diets

    As children get older and become more independent they may decide to follow particular diets or restrict certain food groups. There are many diets that adolescents may find appealing, and it is common for older children to experiment with ‘fad’ diets. Unnecessarily restricting particular food groups may result in nutrient deficiencies which can be detrimental to health as your child may be missing vital nutrients for growth and development (e.g. going gluten-free when it’s not needed, low-carb diets).

    Adolescents who restrict their intake of animal products (meat and dairy) are particularly at risk of iron and calcium deficiency, especially if choosing to eat a vegetarian or vegan diet. Iron is needed for transporting oxygen to the body, and lack of iron often presents as a lack of energy. Including foods that contain iron in the diet to prevent iron deficiency is important for both physical health and brain development.

    Calcium is required for healthy bone growth, particularly during adolescent growth spurts. Inadequate intake of calcium in adolescence can lead to osteoporosis or weak bones in adulthood.

    • If your child has decided to restrict certain food groups, or has decided to follow a special diet, speak to a GP and dietitian about implementing a balanced diet that meets nutritional needs.
    • Following a diet that isn’t planned or supervised by a health professional could lead to poor health.


    Children and adolescents who are underweight or overweight can be nutritionally deficient as their diet usually lacks healthy nutrient-containing foods.

    While there are many factors that contribute to a child’s weight (e.g. genetics) it is heavily influenced by their food choices. Common dietary contributors to excess weight gain include junk foods, sugary drinks, large portions and processed takeaway foods. Overweight children do not naturally ‘slim down’ or lose weight as they get older: they require healthy eating habits in conjunction with exercise to reach a healthy weight.

    Poor food choices

    Treats and processed foods (chips, chocolates, lollies, cakes, biscuits and take-away food) should be limited to special occasions and be consumed in moderation in accordance with the Australian Guide to Healthy Eating.

    Sugary drinks (soft drinks, juice, flavoured waters, cordials and sports drinks or energy drinks) are not required, even following sport, and should be avoided. Water is the healthiest choice and should be the main drink for all children over 12 months.

    Treats, processed foods and sugary drinks are often filled with sugar or artificial sweeteners, fat or salt and add no nutrition or benefit to a child’s diet. Too many serves of these foods and drinks are linked to poor health, weight gain and tooth decay.

    • Reduce the number of treats offered to children and teenagers and provide healthy alternatives for snacks.
    • Avoid using treats as rewards – using treats for behavioural or emotional reasons does not support the development of healthy eating habits.

    Care at home

    Generally, most vitamin deficiencies can be managed at home with minor changes to diet. Making healthy food choices and knowing how many serves your child needs for their age can be helpful. See more at the Australian Guide to Healthy Eating.

    • Involve your child in planning meals, food purchasing and preparation – these improve your child’s understanding of healthy eating and their food choices.
    • Reduce the number of treats available and provide healthy alternatives for snacking.
    • Avoid buying or offering sugary drinks – water is the best drink for children.
    • Include a variety of fruits and vegetables in your child’s diet.
    • If your child has special dietary requirements or needs to avoid particular food groups, ensure they eat appropriate foods to replace the nutrients they miss out on.

    Reading labels

    Reading food labels is the best way to know how healthy a product is. Always look for the fat and sugar values as these will guide you in making good choices.

    • There are many names for fat (e.g. oils, shortening, milk solids, monoglycerides) and sugar (e.g. sucrose, glucose, dextrose, syrups, malt).
    • Ingredients are listed in descending order (i.e. a product contains the most of the first ingredient and the least of the last ingredient).
    • Use the ‘Per 100g’ values listed in the nutrition information panel to compare products.
    • The fewer ingredients listed, the better.

    There are resources and apps that can help understand labelling. Try Eat for Health or the FoodSwitch app.

    When to see a doctor

    You should take your child to see your GP if you are unsure about your child’s general health, weight or diet. Your GP will be able to refer you to a dietitian for additional support to ensure your child has a balanced diet.

    You should also see your GP if your child or adolescent:

    • is avoiding food groups or restricting their diet
    • has allergies or food intolerances
    • has an unbalanced diet and you are concerned about nutritional deficiencies
    • is underweight or overweight.

    Key points to remember

    • A nutrient-rich diet is important for healthy growth and development.
    • Generally, most vitamin deficiencies can be managed at home with minor changes to diet.
    • You should take your child to see your GP if you are unsure about their weight or diet or if you are concerned they may have an allergy to particular foods.

    For more information


This information is intended to support, not replace, discussion with your doctor or healthcare professionals. The authors of these consumer health information handouts have made a considerable effort to ensure the information is accurate, up to date and easy to understand. The Royal Children's Hospital Melbourne accepts no responsibility for any inaccuracies, information perceived as misleading, or the success of any treatment regimen detailed in these handouts. Information contained in the handouts is updated regularly and therefore you should always check you are referring to the most recent version of the handout. The onus is on you, the user, to ensure that you have downloaded the most up-to-date version of a consumer health information handout.