Sugar

We all know sugar gives us energy, and while we could discuss the science of why that is, you've only got to watch kids at a party fuelled by cake and sweets to know it's true.

There's a bit of a history of controversy when it comes to sugar and ADHD, largely fuelled by the unfounded idea that high sugar consumption in childhood causes ADHD: completely untrue of course (Del-Ponte et al, 2019)^[1]. Unfortunately, this misunderstanding means some consider sugar harmless, when in fact there is a relationship between sugar and symptoms of ADHD, although we don't yet understand the full extent (Farad-Naeimi et al, 2020)^[2].

There are further reasons why sugar isn't a great idea for adults with ADHD.

• There is an association between ADHD and dysfunctional dopamine signalling (AArts et al, 2015)^[3], and high fat/high sugar diets are known to affect the availability of dopamine in our brain (Hartmann et al, 2020)^[4]
• There are correlations between ADHD and obesity that go beyond impulsivity control (Faraone & Larsson, 2019)^[5]. A high sugar diet does result in fat stored in tissue around our middle (I'll bore you with the science in a later blog), so it makes sense that if a person has a biological propensity to obesity or weight gain, keeping sugar low will help manage that.
• There is an association between ADHD and altered blood-glucose stability in children with type 1 diabetes and adults with type 2 diabetes (Leshno et al, 2025)^[6]
• Anxiety is the most common co-occurring condition with ADHD (Katzman et al, 2017)^[7]. High sugar intake makes our body's response to stress worse. To explain: when faced with stress, our brain triggers a response via something called the HPA axis. Simply put, it starts with adrenaline (that increases our heart rate and sometimes makes us sweat), then goes through a series of chemical reactions resulting in cortisol production. Cortisol increases blood pressure, heart rate, how much glucose we have in our bloodstream, and how our brain uses glucose. It's what we need for a high stress situation, but in anxiety, this happens too often. If you add have a high sugar intake then you are adding fuel to the fire, because when blood sugar peaks and drops quickly, the body triggers an adrenaline cycle again. This repeated activation of our HPA axis (adrenaline to cortisol) is linked with type 2 diabetes, obesity, cardiovascular disease, even negatively affecting memory and cognition, and is implicated in depression (Chrousos, 2009)^[8]. Keeping our blood sugar stable helps us avoid serious long-term health conditions, and regulate our emotions better on a daily basis. It may seem a small change but it has big consequences!

So how do we eat in a way to keep blood sugar stable?

• have protein with each meal, as protein and fat slow down the release of glucose into your bloodstream. Protein includes nuts, eggs, meat, fish, cheese, tofu etc.
• swap white starchy foods (white rice, white flour, white pasta) with wholegrain options (e.g. brown basmati rice, wholewheat flour etc)
• if you fancy cake or chocolate, eat it just after the savoury/protein part of your lunch, which helps minimise the impact on your blood sugar
• to sleep better at night, don't eat sweet things in the evening
• avoid drinking alcohol on an empty stomach, have a handful of nuts first or drink with a meal
• never ever ever have sugary drinks (including those with sweeteners and concentrated fruit juices), as they have shown to be particularly influential on symptoms of ADHD and raise blood sugar very fast

Healthy oils

Fish oil supplements are big business, with the global market valued at over $2 billion in 2023. Online articles about ADHD promote polyunsaturated fatty acids (PUFAs) as symptom-reducing supplements. So are the claims hype or fact? Does our body and brain really need omega 3 and 6, and what role, if any, does it play in ADHD?

Our brains are comprised of 60% fat, 10-15% of that is docosahexanoic acid (DHA). DHA from the food we eat can pass through the blood/brain barrier via a special transporter called Mfsd2a, which ‘flips’ it across the lipid bilayer.^[9] Eicosapentaenoic acid (EPA) is also a major part of neuronal membranes. In the brain, DHA and EPA have a wide range of functions, including modulating the connections between our brain cells, managing the connection between our brain and our immune system, and protecting our brain and nerve cells from damage. A review of animal and clinical studies showed that omega 3 fatty acids have cognitive-enhancing effects across all age ranges, but particularly in developing, aged, or cognitively impaired people.^[10] Other omega 3 fatty acids (such as DPA) may also have some therapeutic potential in brain health, but research is limited although promising.^[11]

Omega 3 and omega 6 are also connected to inflammation. Essential fatty acids are metabolised through several enzymatic steps before they become metabolically active. One key metabolic end product is prostaglandins: communication compounds which regulate our inflammatory response. Omega 3 fatty acids produce series 1 and 3 prostaglandins, which help to reduce and ‘switch off’ inflammation (with series 3 being the most anti-inflammatory). Omega 6, on the other hand, produce series 2 prostaglandins, which are powerfully pro-inflammatory. We still need omega 6, but generally speaking, our diet in the Western world gives us an intake in a ratio of 10:1 omega 6 to 3, when ideally we should be aiming for 2:1 omega 3 to 6. This connection with inflammation is worth mentioning, as there are links between neuroinflammation and ADHD.

Let’s consider another omega 3 fatty acid, specifically alpha-linoleic acid or ALA. This is the fatty acid found in non-marine sources, such as in nuts and seeds, and is often used by vegans or vegetarians as a substitute for EPA/DHA. However, the human body is not able to convert ALA to EPA/DHA well, in fact we only convert about 5% of our ALA intake to EPA and just 0.5% to DHA, so it is not a performant substitute for marine-origin EPA and DHA. That said, there is some research that ALA may have some beneficial effects on the brain in its own right, including sustaining blood/brain barrier integrity and boosting resilience against Alzheimer’s.^[12] However, the primary omega 3 fatty acid needed in our brain is DHA.

While we have outlined the important roles of omega 3 fatty acids, arachidonic acid (AA) from omega 6 is also one of the most abundant fatty acids in our brain - together with DHA it makes up about 25% of all the fatty acids in the brain. We convert it from linoleic acid, found in nuts and seeds. AA helps us maintain membrane fluidity in the hippocampus - the part of our brain that controls memory and spatial awareness. It’s involved with brain growth, and modulation of cell division and signalling. It also protects against neurodegeneration, the root of diseases such as Parkinson’s and Alzheimer’s.^[13] It also increases the uptake of glutamatic acid, which is lower in individuals with ADHD.^[14] So omega 6 is also an essential fatty acid for our brain health.

Some studies suggest that as stimulant medication for dopaminergic pathways do not improve symptoms for all individuals with ADHD, that there is glutamatergic involvement in ADHD pathophysiology, with animal models suggesting altered glutamate regulation of the dopamine system is what underpins the functional deficits with ADHD. The above Maltezos study found lower basal ganglia levels of glutamine and glutamate were significantly associated with more severe symptoms of inattention in ADHD.

We all need omega 3 and omega 6 for our brain development, maintenance, and protection. But is there any evidence that these essential fatty acids can help modulate the symptoms of ADHD?

A study in Italy that supplemented both omega 3 and omega 6 to 6-12 year-olds with ADHD (two capsules containing 279 mg EPA, 87 mg DHA, 30 mg GLA each) found no superiority to placebo in 6 months of treatment, in terms of improving attention.^[15] A French study in 2018 also reported no beneficial effects of omega-3 supplementation for mild ADHD symptoms.^[16] These studies, however, do not align with other clinical trials that noted supplementation of omega 3 led to a reduction in symptoms of inattention, less marked impulsive behaviour, and a general reduction (25% or more) in all ADHD symptoms, as well as an improvement in working memory.^[17] Other specific trials showed benefits with ADHD comorbidities, with omega 3 supplementation producing excellent results in reducing seizures in ADHD and epilepsy.^[18]

So why the contradictory results?

A clue might be in a Chinese study from 2019, that measured blood erythrocyte PUFAs to examine the effects of baseline endogenous EPA levels on treatment response. It found that those with low levels of EPA were more likely to see improvements in attention.^[19] Another study on plasma profiles in ADHD found that those with the best response (i.e. reduction of ADHD symptoms) to omega 3/6 supplementation had the greatest change in serum omega 3 and improvement in omega 3/6 ratio after 6 months.^[20] This could mean that individuals with ADHD who have an omega 3/6 imbalance (more 6 than 3), and who have a low dietary intake of omega 3, are the most likely to respond well to supplementation of omega 3. It’s interesting the study that found no change was from Italy, who are already eating a Mediterranean diet and likely to have a better balance from their diet already.

This theory is supported by a meta-analysis of omega 3 deficiency and ADHD from the US - they found 9 studies confirming lower overall blood levels of omega 3 in individuals with ADHD vs controls, and 16 studies showing omega 3 supplementation improved ADHD composite symptoms.^[21] A UK study also showed that low blood levels of omega 3 in ADHD are related to abnormal emotion processing and dysregulation in boys.^[22] Interestingly, this may have genetic origin, with a 2006 study finding that, from a sample of 180 children with ADHD and 180 controls, those with ADHD had a 60-70% greater chance of variation in the gene necessary to metabolise fatty acids.

Neuroinflammation was considered in a recent study on adults with ADHD, that looked at 96 inflammatory proteins in 126 adults with ADHD (from Spain, Germany, and Hungary) and the link with chronic stress. Two distinct biotypes came out as a result: High inflammatory potential (HIP) and Low inflammatory potential (LIP). The HIP group were more likely to have higher levels of chronic stress, a higher CGI-severity score (a scale on which a clinician ranks the patient’s mental health), and a higher risk of suicide. Interestingly, no association with ADHD medication nor other demographics such as sex, BMI, obesity, tobacco use, vegan/vegetarian nutrition, or age was found between LIP and HIP groups. The exception was that DHA consumption was higher in the LIP group in Germany, and omega 6 consumption higher in the HIP group from Spain. The report concluded, “Higher levels of inflammatory proteins in ADHD are linked to higher levels of chronic perceived stress in a linear fashion”.^[23] While the study made no comment on EFA intake, the results are interesting. Again we can see an association with ADHD, neuroinflammation, stress, and the anti- or pro-inflammatory effects of EFAs, 3 and 6.

Apart from the study discussed above, the participants in the rest of the studies quoted were children or teenagers. More research needs to be undertaken on the effect of omega 3 on adults with ADHD, and studies on children should factor in their usual diet as well as baseline levels of both EPA and DHA for the results to be more meaningful. It may also be useful to know if a study participant had a genetic dysfunction in fatty acid metabolisation. That said, there is enough supporting evidence to indicate that omega 3 does have a positive benefit on the symptoms of ADHD for many, likely as a result of reducing neuroinflammation, and should therefore be part of the nutritional toolkit of anyone with ADHD for managing symptoms, particularly those whose current diet excludes a regular intake of oily fish and includes an excess of omega 6 from vegetable oils used in processed foods and cooking.

Probiotics

Researched and waiting to be uploaded!

Nutrients

Researched and waiting to be uploaded!

Highly processed foods

Researched and waiting to be uploaded!

Food sensitivities

Researched and waiting to be uploaded!

If you'd like more information in the meantime, please feel free to get in touch