Can nutrition deficiency be linked to a child’s behaviour?

The simple truth is, you are what you eat. The food a growing child eats directly impacts their behaviour and physical and psychological profile.

Though children often crave foods which are high in sugar (sweet treats) refined carbohydrates (fizzy drinks, white bread) and saturated fats (junk food), this type of diet can cause nutritional deficiency.

Poor quality diets which contain lots of these foods are low in vitamins, minerals and unsaturated (good) fats, which don’t give kids the nutrients they need for growth and energy.

The effects of nutritional deficiency include: poor brain development, weak learning, low immunity, stunted growth and more. [1]

The behavioural impact? Hyperactivity followed by irritability and fatigue, caused by unstable blood sugars. Inability to focus, aggressive behaviour, impulsivity and more.

Environmental factors for nutritional deficiency

In Hong Kong, nutritional deficiencies are worsened by the fact our fresh fruits and vegetables often contain insufficient vitamins and minerals due to poor soil quality and long haul food importation.

Other factors which contribute to deficiencies include toxins (like pollutants, heavy metals and mould), digestive conditions (Crohn’s or celiac disease), other malabsorption conditions, pharmaceutical drugs (like overuse of antibiotics) and stress.

So it’s possible that your child is eating a high quality diet, but may still be deficient.

Symptoms of nutritional deficiency in children

Symptoms of deficiency are wide-ranging, and could vary from mild to debilitating. They may go undiagnosed, or misdiagnosed. Symptoms to take note of include:

  • Bedwetting.
  • Persistent colds or infections.
  • Allergies, wheezing, stuffy noses and sweating.
  • Hyperactivity, irritability, twitching and restlessness.
  • Digestive issues like constipation, diarrhoea and stomach aches.
  • Fatigue.
  • Poor attention span and difficulty in school.
  • Eating non-food items like stones, hair or ice (also known as pica).
  • Poor growth.

Common nutritional deficiencies in kids

These nutrients are essential for both brain and physical growth. It’s important these deficiencies are remedied so your child hits their markers for physical, emotional and mental development.


If left untreated, iron deficiency can have irreversible effects on neurotransmitters, affecting cognitive, motor and social-emotional function. [2]

In the short term, iron deficiency can cause kids to look pale, be moody or tired, and feel dizzy or lightheaded. These symptoms can lead to poor performance in school. Eating ice is often a sign of iron deficiency.


Magnesium deficiency is common in children, especially those who are diagnosed with ADD or ADHD.

Common signs include loss of appetite, muscle cramps and tension, fatigue and nausea. Picky eaters are particularly at-risk, as magnesium is found in brown bread, kale, spinach, fish and nuts.

Studies on kids with ADHD and magnesium deficiency reveal that after supplementing with magnesium and B6 for 2-6 months, their symptoms improved dramatically.

Two thirds of those with physical symptoms, like muscle tension, resolved their physical symptoms, while behaviours like inattention, aggression, hyperactivity and impulsivity normalised by 75%.


Signs of zinc deficiency in children include poor appetite and growth and persistent colds. In terms of their behaviour, this deficiency can lead to emotional instability, anxiety, aggression and irritability. [3]

The bodies of zinc-deficient kids are also less responsive to medications (including stimulants used to treat ADHD) and essential fatty acid supplementation.

Treating zinc deficiency can help repair your kids’ immunity while balancing behavioural issues and stimulating their appetite and growth.


Nutrients like vitamins A, C, D and E, as well as B complex are essential for brain development and immunity building. During childhood years, B complex is particularly important for brain and nerve development.

Deficiencies in these areas can cause a range of behavioural issues. Vitamin D deficiency can increase impulsivity, rule-breaking and aggression; vitamin C can cause fatigue and weakness; B complex deficiencies can delay mental development, cause irritability and anxiety and depression.

Another side effect of deficiency is reduced antioxidant levels. This increases oxidative stress, which is a contributing factor for conditions like autism and ADHD.

Essential Fatty Acids

Fat makes up 60% of your brain’s weight. These fats are mainly omega 3 and 6, the primary forms of which are EPA and DHA, the two essential fatty acids found in fish.

Deficiencies in omega 3 can manifest as eczema, asthma, poor immunity and behavioural issues like aggression. Low levels of omega 3 are also common in kids with ADHD and studies have shown that supplementation reduces hyperactivity, impulsivity and poor focus.

Omega 3 fatty acids help improve brain function and mood in kids. If your little one refuses to eat fish, supplementing with a quality fish oil is an easy alternative.

In summary

We recommend a standard supplement regime of a high quality multivitamin, omega oil and probiotic for all kids living in Hong Kong. Our practitioners have sourced the best quality supplements from around the globe, so that you don’t have to. These science-led formulas are available from our online shop, or dispensary in Central.

If you have identified signs that your child may have other nutritional deficiencies, it’s best to get them checked out by a professional.

Our naturopaths are experienced in diagnosing nutritional deficiency, and can refer your child for any tests if needed. They can also recommend dietary changes or supplements to ensure that your child gets the nourishment they need to grow up healthy and strong.

If treated, nutritional deficiency doesn’t have any lasting effects and can improve behavioural problems related to their nutritional profile.

 [1] UNICEF, Poor diets damaging children’s health, warns UNICEF, 2019.

[2] B Lozoff et al, Long-lasting neural and behavioural effects of iron deficiency in infancy, 2006.

[3] S Hagmeyer et al, Behavioural impairments in animal models for zinc deficiency, committed to providing the purest, high-quality supplements.  Clinical grade & practitioner recommended, we’ve worked hard to source the best, so you don’t have to.  

Simply visit our dispensary in person, or 

What’s next?

Unsure if your child’s behaviour is linked to nutritional deficiency? Our naturopaths can refer you for tests to confirm whether your child has a deficiency, and prescribe industry-leading supplements to fill nutritional gaps.

Return to your natural state of wellbeing with the help of our naturopaths.

Simply call +852 2523 7121 or complete your request below, and we'll be in touch shortly to confirm your appointment.

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