Four metabolic reasons why your autistic child may be aggressive or self-harm

Autism in its purest form can be very special and we can learn a huge amount of wonderful things from autistic children. However, it is devastating when autistic kids behave aggressively, or they start to hurt themselves and family members.

In educational settings this oppositional behaviour and aggression can often lead to school exclusion. Very often this can occur when they are having trouble understanding what is happening around them or having difficulty communicating their own wants and needs.

Troubles with communication can make them very anxious and stressed, which can not only lead violent outbursts and self-harm, but also autistic meltdowns and sometimes shutdowns or burnout.

Many families are frightened living under the same roof as their autistic child, and they walk around them as if on eggshells, so that no one gets hurt and their things are not destroyed. Many autistic teens and adults need more than one carer with them round the clock due to their aggressive tendencies.

It is of course important to learn specialist techniques to be able to improve communication with your child and to also make adjustments to embrace their world and their specific needs with an attempt to prevent these episodes. However even with the best care and love, these aggressive outbursts can still be there in spades, and it is hard to cocoon someone entirely from the unpredictable nature of the outside world.

There are some underlying nutritional and biomedical brain imbalances known as co-morbidities, that can go alongside autism. These imbalances can predispose someone to a more emotionally dysregulated state and magnify aggression and self-harm tendencies. These are relatively simple to explore and to support and may make all the difference to establishing a more balanced and even mood as well as long term ability to manage anxiety and change.

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Blood Glucose Balancing

Have you ever felt “hangry” mid-morning or when a meal is running late? This is when your blood glucose goes too low and symptoms can include irritability, difficulty concentrating, light headedness, feeling weak, sweating, or shaking. Research has found that autistic people can find it harder to regulate their blood sugar levels and this hangry feeling can lead to aggression. They are also more prone to developing both type 1 and type 2 diabetes, so it is important to address this early on.

If blood glucose imbalance is a problem, then you can usually nip things in the bud by giving them something to eat when you can see their mood changing or to put in structured snack times throughout the day. Eating enough protein and healthy fats are key when it comes to better blood sugar balancing. Also explore whether they would benefit from magnesium, vitamin B1 or chromium which all help to keep blood sugar balanced.


There is a genetic metabolic issue linked with how we regulate zinc and vitamin B6 called kryptopyrrole or pyrrole disorder. It is essentially where we urinate out more zinc and vitamin B6 than we consume in our diet, and this can lead to a plethora of issues associated with neurodivergence.

Mood swings is the most highly reported symptom of kryptopyrrole, followed closely by social withdrawal, compulsive behaviour and emotional eating. Poor stress control, nervousness, anxiety, inner tension, episodic anger and depression are other common signs. Violent and destructive behaviours have been reduced dramatically from addressing these biomedical imbalances stemming from having a pyrrole disorder.

A simple inexpensive urine test can identify if this part of the picture, and addressing nutrient deficiencies including consuming more zinc and vitamin B6 rich foods and taking food supplements can positively influence mood in as little as six weeks.

Low Cholesterol

It is ingrained in our thinking that cholesterol is “bad” and we assume that the lower the cholesterol the better. However, this is not the case and in fact we all need some cholesterol to help us synthesise vitamin D and to help make our sexual hormones like testosterone and oestrogen.

Cholesterol is one of the primary fats in the brain and irritability, aggression and self-injurious behaviour have all been linked with very low cholesterol levels. Low cholesterol is common in autistic people, not least because they tend to be highly selective eaters and can often avoid foods naturally high in cholesterol such as liver, heart, kidneys, butter and eggs. Finding clever ways to incorporate these foods can help some autistic people quite dramatically.

High Glutamate

We have two very important neurotransmitters that act like a seesaw in the brain – glutamate excites the brain and GABA does the opposite and keeps it calm and relaxed. Research has found that too much glutamate can lead to repetitive thoughts and behaviours that can escalate to aggressive behaviour and self-harm.

A high glutamate state can also mean that perception of pain can be altered, which means that it may be harder to ameliorate pain easily. Non-speaking autistic people can often express pain such as headaches, migraine, toothache, gut pain and joint pain as aggression or self-harm, especially if they are unable to communicate where the pain is bothering them. It is easy for this to slip out of balance and very often autistic people inherit difficulties balancing their glutamate and GABA.

Our modern food habits do not help, as much of what we now eat is abundant in glutamate – free glutamate is often found in ultra-processed snacks and foods. The ingredients to look out for in addition to monosodium glutamate (MSG or E621) are yeast extract, hydrolysed protein, natural flavourings, fruit extracts, vegetables extracts and citric acid. Free glutamate is naturally found in the tasty “umami” foods such as ketchup, soya sauce and Worcestershire sauce.

GABA rich foods on the other hand tend to be an afterthought in the diet. They include foods such as live yoghurt, kefir, oats, barley, brown rice, spinach, sweet potatoes, yams, kale and chestnuts as well as chamomile tea.

Round up

My work has always primarily been to support autistic children nutritionally, so they can positively thrive with their autism and also stay safe in the world. And as you will have read in this blog there are several co-morbidities which can predispose an autistic person to aggression and self-harm.

This is a large part of the clinical work that my Neurodivergence team and I do at NatureDoc. To make this information more accessible and to empower parents to be able to help their child lead a more balanced and happier life, I have created a Nutrition for Autistic Children Online Course.

The information in this public blog is just a small snapshot of the one of the many topics I cover in this incredible resource. This course shares my clinical pearls and easy-to-action nutritional changes from my twenty years of working with autistic children, and there is also a discussion forum and a Live Q&A option so you can get some more individual support, as well as being part of a community of other families going through a similar experience.

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