What does ultra-processed food have to do with ADHD?

Ultra-processed food is a hot topic as most of us eat a lot of it, but the evidence is mounting that it isn’t doing our health much good when we eat too much. And when you bring ADHD into the picture, people have a lot to say and can become quite an emotive subject!

You may have heard about Joe Wicks earlier this year bearing the brunt of it after he was interviewed by the BBC Headliners podcast all about his personal experience with hyperactivity, impulsivity, and poor focus as a child, which he puts down to eating too many ultra-processed foods such as Sunny Delight, Wagon Wheels and jam sandwiches.

This interview was then featured in The Mail and upset some people in the ADHD community as he may have implied (but he did not actually say, and nor did the Mail) that a diet high in ultra-processed foods causes ADHD.

As a nutrition professional and author who has been studying the links between nutrition and attention deficit and running a clinic specialising in this for over 25 years, I would like to help clear some things up. I am also a fellow ADHDer, with a husband and two kids with ADHD who all feel rubbish if we eat too many ultra processed foods and really thrive when we eat lots of nutritious brain foods.

If you are curious, why don’t you try just one-week challenge of keeping UPFs to below 20% of your diet and see if you and your kids feel better balanced and focused? I’d be fascinated to know how you get along!

Most of my followers will know I bang this drum a lot, so please forgive me for going back to basics about UPFs for anyone new to this.

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What is ADHD?

Attention Deficit Hyperactivity Disorder is a complex neurological condition affecting focus and impulsivity. It is a neurotype with two main variants: inattentive (largest number of people) and hyperactive; but both can be present.

There is a growing number of both adults and children worldwide with ADHD, with an enormous uptick in recent years, particularly in the Western world. Theories for this include that it is due to greater awareness and diagnosis of neurological differences, so it’s now just easier to spot.

ADHD is thought to be highly heritable and genetics plays a huge role in whether someone displays symptoms of ADHD. There is a set of risk genes that have been identified, but no single gene that causes ADHD. Equally brain scans have also identified patterns that can mean ADHD is likely. Still, these are inconclusive, as the human brain is a complex beast, and everyone is unique.

There is also evidence that diet and lifestyle can change the expression of specific genes, which means that even if you have inherited genes that predispose you to ADHD, the symptoms may be less apparent if you eat a healthy, nutritious diet and exercise. This field of research is known as epigenetics, and understanding this subject in more depth can help to give people more agency over managing their own and their child’s ADHD symptoms.

Finally, our mood and mental health is heavily influenced by our gut microbiome whether you have ADHD or not; so it should be no surprise that the severity of ADHD symptoms can be affected by it too, according to research.

The problems surrounding diagnosis and medications

Getting a diagnosis for ADHD involves a psychiatrist and requires input from professionals as well as parents and schools, which means a lot of paperwork and time. The often-long and frustrating process includes finding the right medications and dosage, as well as making adjustments at home and school to support a person’s well-being.

However, lengthy NHS waiting lists and shortages of ADHD medications mean many adults and children struggle without a diagnosis or access to the medical treatment options. Additionally, some people don’t respond well to medications and may experience side effects like loss of appetite, poor growth, headaches, and trouble sleeping.

Toddlers and young children showing signs of ADHD are not able to get a formal diagnosis until they are old enough, leaving parents and teachers frustrated with needing to wait several years. With schools overwhelmed by children needing specialist support, including many with ADHD, the system is struggling to accommodate those with severe behavioural symptoms, as evidenced by the high exclusion rates reported in 2022.

Why should we look at diet and ADHD?

There is both historical and emerging evidence from the scientific literature that diet and nutrition play a role in managing the symptoms of ADHD. If you search for ADHD and Diet in PubMed, you will find around 677 papers and in these the authors tend to use words such as “odds of having” or “positively correlated with the risk of” instead of cause.

Many studies discuss the link between diet and nutrition and the reduction of ADHD symptoms, often finding that eating a healthier diet can mean better focus, less impulsivity, better sleep, and more robust self-esteem and mental health. So, the underlying ADHD is still there, but it is much better managed.

Historically, studies on nutrition and ADHD are where researchers compare symptoms of ADHD between cohorts of children who follow different dietary patterns. A few types of diet are often cited in these studies, and these include quite generalised terms such as Healthy, Junk Food, Western Diet, or Vegetarian.

Because ADHDers tend to be quite sensitive to the food they eat and their environment, there have also been studies looking at specific diet changes such as removing artificial food colours, the few foods diet (which is essentially a diet containing foods that are least likely to pose allergic or reactions or hyperactivity such as rice, meat, vegetables, pears, and water), as well as a diet abundant in omega-3 fatty acids from eating plenty of oily fish and other foods rich in essential fatty acids.

Interestingly, there is very little direct research on sugar intake and ADHD. However, quite a few studies cite links between consumption of ‘sugar-sweetened beverages’ with symptoms of hyperactivity, lack of focus, and impulsivity. Possibly one reason for this is that sugar itself is not bad for you in small amounts, but excessive refined sugar causes peaks and troughs in your blood sugar levels, which is bad for you. So products which are associated with repetitive sugar spikes are more likely to be an issue.

The term ultra-processed food (UPF) is relatively new, so this is probably why there is limited direct research on the links between eating too many UPFs and ADHD, but the research is there, and there is much more long-standing evidence if you look for the words like junk food and Western diet. Anyone disputing this is overly focused on semantics!

Eating too many UPFs have been found to affect brain function overall and there are strong links between UPF consumption and the effect on executive function, which can be a crucial challenge for people with ADHD. Research has also found that an excess consumption of UPFs can lower verbal reasoning scores which affects skills like reading comprehension, critical thinking and problem solving as well as effective communication.

Why is this a problem now?

Experts advise that a healthy diet contains about 80% home cooked or minimally processed food, so it is OK to eat around 20% UPF, which could be around 4 meals a week. However, that doesn’t account for blissy high-carb snacks which spike blood sugar in between meals.

The consumption of ultra-processed foods has escalated in the UK and other Western countries, and there seems to be no stopping in this shift towards eating highly processed convenience food.

A study published in 2019 found that British toddlers consumed up to around 75% of UPF foods. And it gets worse as they get older, with teenagers and adolescents consuming around a staggering 83% of UPF foods in their diet. So, if our kids are now two-thirds ultra-processed these days, two-thirds of their diets lack many of the essential nutrients necessary for child development and a healthy neurological system and brain.

It worries me that there will be far-reaching ripple effects in the future. Maybe we are seeing it already if short attention spans have become a generational norm, anxiety and irritability is everywhere, and IQs are in decline.

How do UPFs affect the brain?

Ultra processed foods are convenient, taste delicious but they can be extremely addictive. They are created with a long shelf life and profit margins in mind, sometimes at the expense of nutrition.

Lacking amino acids that make dopamine
Most ultra processed foods are predominantly made from refined and modified starches and contain relatively little of the more expensive proteins or healthy fats. So if your diet is filled with UPFs, this can mean you are likely to be eating an unbalanced diet with a skew towards eating too much carbohydrate. Since the amino acids from eating protein are the key building blocks for making the neurotransmitters involved with ADHD like dopamine and norepinephrine, a shortfall in these may lead to glitchy neurotransmitter production.

Hyper then hangry, the UPF effect
Having too many carbs without the balance of proteins and healthy fats can also affect blood glucose which in turn can affect focus and impulsivity. Research has shown that many neurodivergent people are very sensitive to blood glucose highs and lows, and this can lead to a pattern of being hyper and then ‘hangry’. If a food has a high glycaemic index, which means the blood glucose spikes up and down rapidly, then this is not going to do that kind of brain any favours and exacerbate things. Table sugar has a glycaemic index of 65, whereas ultra-processed foods like sweet cereals are around 74, cornflakes are around 82 and rice cakes are higher at 90. Oat milks can be even higher. So all these can be worse for the blood sugar highs and lows if consumed alone.

Lack of brain food vitamins, minerals and omegas
UPF foods tend not to contain many of the key vitamins, minerals and essential fatty acids that you get from eating home cooked food. ADHDers can be very sensitive to even small shortfalls in these vitamins and minerals as they are also critical for helping to make, synthesise and reuptake dopamine and norepinephrine. These nutrients include zinc, magnesium, iron, B vitamins, and omega 3.

Often the processing destroys natural vitamins in food, so it is added back in the form of artificial nutrients that are not so readily absorbed as the real thing.

Additives effect on the gut microbiome
Even though the evidence is only just emerging, it is thought that the emulsifiers, preservatives and artificial sugars in UPF foods may also disrupt the gut microbiome which again is another place where our body makes dopamine and norepinephrine. A healthy microbiome also helps to regulate inflammatory pathways in the body and the emulsifiers and other additives can be pro-inflammatory, which, over time, can lead to neurological changes which may exacerbate their ADHD symptoms.

What you can do

We must remember that diet is not the whole story. There are, of course, other reasons that play a role in ADHD-type traits these days, such as too much screen time and not enough exercise. Symptoms vary from person to person, and the importance of individual environmental factors varies too.

Diet can be a very emotive and polarising subject, and parent guilt should never be involved when feeding a child with ADHD what they need. I know how hard it can be to change mealtime habits for a child set in their ways, and kids with ADHD can be highly selective and crave the short-term dopamine effect from eating UPFs. However, starting with small changes, such as cooking from scratch and reducing the intake of ultra-processed foods, can make all the difference.

Eating healthier foods does not need to be that expensive when cooking from scratch. And it will have higher odds of containing essential brain food nutrients that help a child have a sharper brain, feel calmer, and essentially happier with greater self-esteem. So it is a great investment now and for your future.

You will see quite quickly if it does make a difference to your child. ADHD is never going to magically disappear (which is a really good thing!), but instead, the benefits of having a brain wired this way, will have a greater chance of shining through with the wonderful and brilliant positives that ADHD can bring.

Lucinda Miller is clinical lead of NatureDoc, a UK-wide nutrition clinic specialising in neurodivergence. She lectures on neurodiversity and nutrition and is the author of three bestselling family cookbooks The Good Stuff, I Can’t Believe It’s Baby Food, and her new book Brain Brilliance is out now.

What does ultra-processed food have to do with ADHD?

Get our lovely Healthy Bites newsletter each week!

What is ADHD?

The problems surrounding diagnosis and medications

Why should we look at diet and ADHD?

Why is this a problem now?

How do UPFs affect the brain?

What you can do

Oops! Brain Brilliance sold out at Amazon within 2 weeks of release, and the publishers are reprinting.

Learn why nutrition is so important for ADHD and what you can do about it with exclusive interviews, practical guides and helpful tips.

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