Introduction

ADHD is a common neurodevelopmental condition affecting 5% of children and 2.5% of adults. It is three times more frequent among males than females and is often linked with other neurodevelopmental and psychiatric disorders. ADHD is characterised by varying degrees of inattention, impulsivity, and hyperactivity, leading to impaired functioning (1).

Several harmful consequences are associated with ADHD, including deficient academic/work performance, social isolation, aggressive behaviour (including delinquency and illegal acts) and even premature death from unnatural causes (such as accidents) (1). 

Background

This section will explore symptoms and causes of ADHD.

Symptoms

Symptoms of ADHD can present differently in children and adults, and impact on attention, impulsivity and hyperactivity.

Inattention

Children and adults with inattention symptoms associated with ADHD would struggle to focus and pay attention to detail or make foolish mistakes when working or playing. They might not complete a given task, find it challenging to sustain attention for an extended period, and often forget belongings (2). 

The main signs of inattentiveness are:

Reduced attention span and easily distracted.
Attempting careless mistakes- in school or work.
Struggling with organizational skills such as time management.
Frequently losing or forgetting everyday belongings.
Struggle to commit to arduous or time-consuming activities.
appearing not to listen while others are talking or when instructions are given

Hyperactivity and Impulsivity

Children and adults with hyperactivity and impulsivity symptoms often feel the need for constant movement. Children frequently act as though they are “powered by a motor” and run around a lot. People of various ages may find themselves talking nonstop, interrupting others, blurting out replies, and lacking in self-control. (2).

The main signs of of hyperactivity and impulsiveness are:

Frequently “on-the-go” and unable to sit still.
Excessive physical movement and talking while interrupting conversations.
 Inability to focus on a task.
Attempting unnecessary risks.
Impatient.
Fidgeting or tapping the hands or feet

Related Conditions

Several children may also exhibit additional signs of other conditions alongside ADHD, including anxiety disorder, conduct disorder, oppositional defiant disorder, depression, sleep problems, autistic spectrum disorder (ASD), dyspraxia, epilepsy, Tourette’s syndrome and dyslexia (2)

The signs mentioned above and related conditions with ADHD can lead to severe issues in a child’s life, including academic underachievement, poor social contact with other children and adults, and discipline issues.

Symptoms in Adults

The symptoms of ADHD among adults are more difficult to identify. This is because to a lack of studies on adults with ADHD (2)

Because ADHD is a developmental condition, it is thought that it cannot manifest in adults without first manifesting in childhood. However, ADHD symptoms in adolescents and teenagers can persist into adulthood. The effects of inattentiveness, hyperactivity, and impulsiveness on adults differ significantly from those on children. Adult hyperactivity, for example, tends to lessen as stresses of adult life mount, but inattentiveness tends to persist. Adult ADHD symptoms are also milder than those seen in children.

The symptoms of ADHD among adults includes: 

Inattention to detail and carelessness.
New tasks are always being started before old ones are completed.
Poor organisational skills.
 Inability to focus or priorities.
Losing or misplacing items on a regular basis.
Forgetfulness.
Restlessness and edginess.
Having trouble being silent and speaking out of turn.
Interrupting others and blurting forth responses.
Emotional ups and downs, impatience, and a short fuse.
A lack of capacity to cope with stress.
Extreme impatience with taking risks in activities, typically with little or no concern for one’s own or others’ safety — for example, driving recklessly.

It is worth noting that adult ADHD can coexist with a variety of other issues or disorders including personality disorders, bipolar disorder and obsessive-compulsive disorder (OCD) (2).

Causes

lthough the precise causation of ADHD is unknown, several variables are believed to be responsible, including (2) (3) (4): 

Genetics: In most cases, it’s believed that the genes you acquire from parents play a crucial role in developing the disorder because ADHD tends to run in families. Research of 894 ADHD subjects and 1135 of their siblings aged 5–17 years old showed a ninefold increased risk of ADHD in siblings of individuals with ADHD compared with siblings of controls
A brain injury that changes brain structure and function. 
Exposure to stress, alcohol, or tobacco during pregnancy or from a young age may cause imbalances in the level of neurotransmitters in the brain, or these chemicals may not work correctly .
A low birth weight or born prematurely (before the 37th week of pregnancy)

Nutrition & Lifestyle Interventions

Encourage a Wide and Varied Diet

NICE guidelines recommend that children, young people and adults living with ADHD follow and appreciate the value of a balanced diet, good nutrition and regular exercise (5). Therefore, the approach for people with ADHD overall health and nutrition is a diet limiting sugary and processed foods and rich in fruits, vegetables, grains, and healthy fats, such as omega-3 fatty acids. 

A study showed that high intakes of fruit and vegetables might help reduce inattention issues. Another more extensive study where researchers surveyed parents of 134 kids with ADHD symptoms to fill a detailed questionnaire about the typical foods the children ate, including portion sizes, over 90 days. Another questionnaire asked parents to rate symptoms of inattention, which is a hallmark of ADHD, in their kids, including difficulty staying focused, not following instructions, difficulty remembering things, and difficulty regulating emotions. Results showed that children who consumed more significant amounts of fruits and vegetables showed less severe symptoms of inattention (6). The study also investigated the efficacy of a 36-ingredient vitamin and mineral supplement to address symptoms of ADHD and poor emotional control. The findings showed that children who consumed the micronutrients had three times higher significant improvement in their ADHD and emotional dysregulation symptoms.

Key Actions for Improving Diet Variety

A healthy balanced diet is vital for all children to ensure all nutritional requirements are satisfied, whilst supporting normal growth and development. Children and adults with ADHD should be advised to implement a balanced diet including a wide range of colourful vegetables and fruits, nuts, seeds, lean meats, fish and dairy products (7). Wholegrains should also be used rather than refined alterantives, as these varieties are higher fibre and can increase alertness while decreasing hyperactivity (8). Snacks can be used when appetite is reduced, or improved weight gain is required (9). However, these snacks should not be high sugar or processed foods, but rather healthier alternatives, such as celery or cucumber sticks and hummus, fresh fruit or natural yogurt with nut butter.

Ensure Hydration

Fluid intake is vital to maintain hydration. Intake of fruit juices and full-sugar drinks should be restricted. Water is essential as the capillaries in the brain dilate if dehydrated. In sustained dehydration, brain cells shrink, affecting children’s brain functions. Children had shown improved IQ scores when they consumed more water (10).

Key Actions for Increasing Fluid Intake

 Sometimes individuals can find it hard to remember, and therefore the below strategies may be helpful for habit formation:

Decant into a container your water for the day and place in the fridge. Set yourself the challenge to empty that container daily.
Add lemon, lime or berries to water to give it a fruity kick and bright colour.
Children may enjoy using reward charts with stickers to encourage them to drink more
Drink caffeine free herbal teas like peppermint, liquorice and chamomile, as these are so great ways of increasing hydration
Set a phone reminder to help develop positive and regular drinking habits
Where there are set routines, try to factor in hydration as a part of this. For example, drinking as part of travelling to and from work or on the school run, or at the same time as checking emails, feeding pets, doing regular errands and preparing meals

Address Vitamin and Mineral Deficiencies

If a range of foods is restricted in the diet, children and young people may benefit from an age-appropriate over-the-counter vitamin and mineral supplement to avoid deficiencies.  

 Several students highlight that deficiencies of nutrients, mainly iron, zinc, magnesium, and vitamin B6, are linked with ADHD symptoms. It has therefore been proposed that addressing such deficiencies may help to reduce ADHD symptoms severity. One piece of research focused on the contribution of iron and zinc supplementation in ADHD among children and adolescents, and demonstrated that low zinc and iron levels were associated with impaired attention capacity and increased hyperactivity, highlighting a pathway mediated by the dopaminergic system. In the study, Zinc supplementation was observed to consistently improve ADHD symptoms (9).

Side effects: Supplements can cause side effects in some individuals, therefore it is essential to consult a doctor and registered dietitian or nutrition practitioner before commencing any supplements.

Contraindications with medication: see above.

Increase Physical Activity

Research suggests that physical movement positively influences brain function among children and adults via improving cognitive processes such as planning, time management, inhibition and working memory. For patients with ADHD, regular physical activity improves brain blood flow and balances brain chemicals such as dopamine, noradrenaline and serotonin.This may have a variety of positive brain health outcomes, including improving memory and concentration, decreasing hyperactivity and impulsivity, elevating mood, and supporting individuals with symptoms of anxiety and depression (11). In one 2019  study, authors reported that children with ADHD developed better impulse control and attention after a 20-minute aerobic exercise session (12).

Key Actions for Increasing Physical Activity

The NHS recommends regarding physical activity:

Toddlers (aged 1 to 2): advised to physically active every day for at least 180 minutes (3 hours) throughout the day, including playing outdoors. 
Pre-schoolers (aged 3 to 4): advised to physically active every day for at least 180 minutes (3 hours) throughout the day, including playing outdoors. The 180 minutes should also comprise of at least 60 minutes (1 hour) of moderate-to-vigorous intensity physical activity.
Children and young people aged 5 to 18: incorporate an average of at least 60 minutes of moderate or vigorous intensity physical activity daily across the week and participate a range of types and intensities of physical activity across the week to develop movement skills, muscles and bones.
Adults aged 19 to 64: do at least 150 minutes of moderate intensity activity a week or 75 minutes of vigorous intensity activity a week spread exercise evenly over 4 to 5 days a week, or every day. 

Increase Omega 3 Fats

Polyunsaturated fatty acid (PUFA) in supplementation, including fish oil particularly omega-3 or omega-6 fatty-acid, is not a current approved treatment for ADHD. The evidence for its influence on ADHD symptoms is mixed. A study showed that it has a small effect for ADHD symptoms, however review concluded “there is limited evidence that PUFA supplementation contributes with benefits for the ADHD symptoms improvement (13). Omega-3 fatty acids can help in supporting  brain function. Some studies show that omega-3s help with hyperactivity, impulsivity, and concentration among children and adults with ADHD (14). Balanced diet, based on eat well plate of two weekly portions of oily fish (such as salmon, herring, mackerel and sardines) or seeds such as flaxseeds and linseeds, is sufficient to meet daily omega-3 or omega-6 fatty-acid daily requirements. NICE guidelines does not advise supplementing patients with dietary fatty acid supplementation for treating ADHD among children and young people. 

Key Actions for Increasing Omega 3 Fats

Eat oily fish, such as salmon, mackerel and sardines, at least twice a week, and seeds, such as flaxseeds (also called linseeds) and chia seeds, on most days. Furthermore, supplement omega 3 through fish oil or a vegan alternative. Look for a supplement that contains both EPA and DHA.

The best fish for EPA, the type of omega 3 fat that’s been most thoroughly researched are: mackerel (1,400mg per 100g/3oz), herring/kipper (1,000mg), sardines (1,000mg), fresh (not tinned) tuna (900mg), anchovy (900mg), salmon(800mg), trout (500mg). Tuna, being high in mercury, is best avoided in autism due to heavy metal considerations.

The best seeds are flax seeds and chia seeds. Flax seeds are so small they are best ground and sprinkled on cereal. Alternatively, use flaxseed oil, for example in salad dressings. While technically providing omega 3 only about 5% of the type of omega 3 (alpha linolenic acid) in these seeds is converted in your body into EPA. Therefore individuals who are following a plant based diet may benefit from supplementing with vegan omega 3 supplements.

Side effects: Causes loose stools in sensitive individuals if they are started on too high a dose.

Contraindications with medication: Essential fats may have a ‘blood-thinning’ effect and should not be mixed with ‘blood thinning’ medication, such as warfarin or heparin. Always consult your doctor before commencing a new supplement.

Eliminate Food Additives

Recent studies indicates a possible association between intake of artificial additives and increased hyperactivity through affecting the mesolimbic dopamine system however, there is not enough strong evidence at the moment to support  this approach as a form of treatment (15). NICE guidelines does not recommend elimination of artificial coloring and additives from the diet as a generally applicable treatment for children and young people with ADHD. 

The NHS encourages to take into account omitting the following colourings if you or your child exhibits hyperactivity after eating certain foods including the ones shown in table 1. NICE guidelines advises to eliminate the certain food or drinks that has a clear influence on you, or your child’s hyperactive behaviour. If you suspect that this is the case with you or your child, implementing a food diary to evaluate if there is an association between certain foods and behaviour might be useful in creating a specific dietary elimination under the supervision of dietitian, mental health specialist or paediatrician, and the parent or carer and child or young person. 

Disclaimer: Always discuss with your doctor before beginning any supplements

Researcher: Ruwaida Ben Sufi, BSc Clinical Nutrition, MSc Obesity and Clinical Nutrition, MSc Dietetics

Useful Resources

NHS, 2022. Eating well with ADHD. [online] Enherts-tr.nhs.uk. Available at: <https://www.enherts-tr.nhs.uk/content/uploads/2019/12/ADHD-leaflet-first-line-advice-updated-1-PDF-2.pdf>

NICE, 2019. Overview | Attention deficit hyperactivity disorder: diagnosis and management | Guidance | NICE. [online] Nice.org.uk. Available at: <https://www.nice.org.uk/guidance/ng87>

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