Often misperceived as ‘bad behaviour’, attention deficit hyperactivity disorder (ADHD) is one of the most commonly diagnosed neuro-developmental disorders in school children in the UK.

Symptoms continue into adulthood and generally fall into three categories: inattentiveness, hyperactiveness and impulsiveness. While it’s common for most children to have difficulty paying attention or sitting still from time to time, for some, these problems are so persistent that they can take an enormous toll on their home, academic and social lives.

‘Pure’ cases of ADHD are also quite rare. There is around a 30-50% overlap between any two developmental conditions, including ADHD, dyslexia, dyspraxia and autism, suggesting a shared biological cause.

Can you cure ADHD?

There is no known cure for ADHD. Treatment focuses on reducing symptoms, usually with a combination of behavioural therapy and medication. Nutrition, however, can also be fundamental.

“There is no question that food and nutrients can impact the symptoms of ADHD…hyperactivity, inattentiveness, learning and behaviour,” says Julie Matthews, a certified nutrition consultant and author of Use Food and Nutrition to Improve ADHD and Autism.

“Not only are the gut and the brain connected, but the entire body and the brain are connected. As you affect health, you also affect learning and behaviour. The science says that you can improve these childhood disorders.

Processed food, sugar and ADHD

In the early 1970s, Dr Benjamin Feingold, a paediatric allergist, caused controversy by suggesting that certain foods and food additives could trigger ADHD. He claimed that 30-50% of his hyperactive patients benefited from diets free of artificial colourings and flavourings.

Since then, numerous studies have associated a western diet, which is typically high in fat, sugar and salt, with heightened ADHD symptoms.

One study found that removing artificial ingredients from children’s diets could be about one third to one half as effective as treatment with methylphenidate (Ritalin), a common ADHD medication.

According to Matthews, not giving children such foods is also the “easiest and most initial action” parents can take.

“Artificial ingredients are highly toxic and very difficult for the liver to break down,” she says. “They are associated with hyperactivity, asthma, aggression, irritability, anxiety, depression, headaches and sleep disturbances.”

Dr Alexandra Richardson, a researcher from the department of physiology, anatomy and genetics at the University of Oxford, says that sugary foods and drinks also cause spikes and crashes in blood sugar. “Replace these with slow release wholegrains that will help to keep blood sugar levels stable, reducing fluctuations in mood, behaviour and concentration,” she says.

Can food intolerances and sensitivities affect ADHD?

In some instances, ADHD symptoms can also be affected by food intolerances and sensitivities. According to Matthews, the two most common in children with ADHD are gluten (the protein in wheat) and casein (the protein in diary).

Unlike an allergy, in which antibodies are produced in response to a given allergen, a sensitivity is thought to involve responses from other immune cells such as T-cells, which are typically delayed in onset, often occurring several hours or days after exposure.

Symptoms can appear over a longer period, and can include, for example, headaches, gut inflammation, diarrhoea, constipation, hyperactivity or anxiety.

An intolerance, on the other hand, is a non-immune, non-allergic reaction caused by enzyme deficiencies in the gut. In the case of a gluten or casein, when not properly digested, the proteins become a source of inflammation by forming opiate-type compounds that mimic the effects of morphine. This can cause symptoms such as brain fog and inattentiveness.

Elimination diets such as a gluten-free, casein-free diet could potentially be helpful. However, Dr Richardson cautions against the use of elimination diets, saying that evidence for their effectiveness is limited and that if adequate substitutes for eliminated foods are not included, then “children can end up with a worse nutritional status than they started with”.

She recommends always seeking the help of a nutrition professional first.

Read more about how to spot a food allergy, sensitivity or intolerance

In the case of a gluten or casein, when not properly digested, the proteins become a source of inflammation by forming opiate-type compounds that mimic the effects of morphine. This can cause symptoms such as brain fog and inattentiveness.

Nutrients for ADHD

According to Julie Matthews, however, ‘dietary intervention’ is commonly misperceived as involving only the removal of foods from the diet. “While avoiding problematic foods is vital, adding nourishing foods in is equally as important,” she says.

This will help to address any nutrient deficiencies common in children with ADHD, including vitamins B6 and B12, calcium, zinc and folic acid.

Good quality animal protein such as red meat, poultry, organ meat, fish and eggs, as well as plant protein foods like nuts and beans are important. When interacting with children, Matthews refers to these as “growing foods” to help children understand food’s role in keeping them healthy. It’s also important to include lots of vegetables (“stay healthy foods”) and sources of healthy fats such as olive oil, avocado, fish oil and animal fats (“brain foods”).

Some fermented foods can also be beneficial in providing good bacteria for the gut.

ADHD and omega-3

A number of studies have shown that the behaviour of children with ADHD significantly improves after they are given a dietary supplement containing omega-3 fatty acids.

Richardson, who has been involved in much of this research, says that the long chain fatty acid known as docosahexaenoic acid (DHA) is most critical. Not only has it been shown to reduce symptoms of hyperactivity, it also supports serotonin and dopamine production, boosting overall mood and improving sleep.

One study found when children, without a diagnosis of ADHD but who were under-performing in reading, were given a supplement containing DHA omega-3, they slept for 58 more minutes a night.

The main sources of DHA omega-3 are fish and seafood. According to Richardson, blood levels of DHA should be in the range of 8-12%, but the average level among British school children is just 2.5%.

“Anyone not eating two portions of oily fish a week should seriously think about supplementing,” she says.

For extra advice, you can also enlist the help of a registered nutritional therapist or experienced practitioner.

“Someone that specialises in nutrition for childhood disorders can help you gain confidence to begin and provide appropriate food suggestions and meal ideas,” says Matthews. “But even if you begin on your own, getting good nutrition, avoiding problematic ingredients and supporting good digestion are practices that will benefit everyone in the family.”

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