Mental Health – Part 6: ADHD & Metabolic Health

ADHD & Metabolic Health

Attention Deficit Hyperactivity Disorder (ADHD) is the most common childhood psychiatric disorder, affecting 5% of children worldwide.  Even if not a typical neurometabolic disease, there are findings that suggest an important role of metabolic health in ADHD.

What causes ADHD?

Theories abound on what causes ADHD:

  • Screen time – including television, smartphones, and video games
  • Environmental toxins – such as lead and pesticides
  • Prenatal health – including poor nutrition and exposure to alcohol or tobacco
  • Trauma – including traumatic brain injury and adverse childhood experiences (ACEs)
  • Infection – such as meningitis or encephalitis
  • Genetics – increased risk among siblings, and 3 in 4 children with ADHD have a relative also diagnosed with ADHD
  • Western diets – ultra-processed foods comprised of refined carbohydrates, sugar, and refined oils

There are multiple associations, but no definitive cause-effect relationship established.  Thus, it is likely far more complex than just a single entity contributing to the clinical picture of ADHD.

Is ADHD a neurometabolic disease?

Given the consistent ADHDrelationship observed between metabolic health and many other aspects of brain health, it serves to reason that ADHD is similarly affected by the same lifestyle factors.  Whether metabolic health is a direct cause remains to be determined.  It may also be that poor metabolic health makes one more vulnerable to other factors, without being a direct cause.  Either way, poor metabolic health appears to be relevant to ADHD.

The following lifestyle factors are associated with an increased risk of ADHD:

  • Obesity; overweight
  • Sugar
  • Preservatives
  • Artificial food coloring
  • Low Zinc
  • Low Magnesium
  • Low omega-3 fatty acids
  • Poor sleep

Knowledge in this area is limited by a lack of good-quality research studies and inconsistent results.  For example, some studies have shown benefits that cannot be repeated in subsequent studies.


Overweight and Obesity

Children with ADHD are twice as likely to be overweight or obese, and vice versa.

Some theorize that individuals with ADHD are expected to burn more calories due to increased physical activity, but ADHD in childhood is actually associated with obesity and physical inactivity in later years.


Nutrient deficiencies are common in ADHD, but the direction of causation is unclear.  Do the nutrient deficiencies drive ADHD behavior, or does ADHD drive poor eating habits that result in nutrient depletion?  Or both?  Some nutritional interventions have been shown to be of benefit, but there is not enough data to support specific recommendations for supplementation.

Children with ADHD tend to have lower levels of DHA, EPA, and omega-3 fatty acids.  Supplementation of omega-3 fatty acids improves symptoms and cognition in children with ADHD.  A review of 10 studies involving 699 children showed a small but significant effect for omega-3 fatty acid supplementation improving ADHD symptoms.

Empty calories such as sugar and refined carbohydrates tend to displace other nutrients from the diet, which drives nutrient deficiencies and prevents the child from acquiring the vital micronutrients for healthy brain functioning.



There is no clear cause-effect between sugar and ADHD, but it appears that sugar can worsen symptoms.  Sugar and refined carbohydrates are rapidly digested in the gastrointestinal tract and then rapidly absorbed in the bloodstream.  The pattern of glucose spikes caused by eating sugar or refined carbohydrates followed by the effect of insulin causing a sudden drop in glucose is a phenomenon that triggers inattentiveness and agitation.

If fluctuations in glucose levels tend to cause symptoms observed in ADHD, one would expect to see more problems in children who have type 1 diabetes, a disease characterized by impaired regulation of glucose that necessitates the use of insulin to lower glucose levels.  Sure enough, there is a significantly increased rate of ADHD among children with diabetes (type 1) than children without diabetes.

There’s consistent evidence that sugar contributes to hyperactive behavior.  In one study, 74% of children with hyperactivity were found to have impaired glucose tolerance.

Another way in which sugar and refined carbohydrates can influence ADHD symptoms is via magnesium.  Sugar can cause magnesium deficiency, which can exacerbate hyperactivity.

Though parents of children with ADHD often report increased hyperactivity after consumption of sugar or sweeteners (as in diet soda), most studies have failed to demonstrate such a finding.  However, sugar consumption increases adrenaline levels in healthy children and also increases aggressive behavior.


Do elimination diets help?

Research in the 1970’s by Feingold claimed improvement with a diet that eliminated apples, grapes, lunch meats, sausage, hot dogs, and artificial flavors and colors.  It was noted that a subgroup of children reacted adversely to a challenge of additives and preservatives.

A diet eliminating common food allergens has also been shown to be beneficial.  These allergens include wheat cereals, nuts, cheese, cow’s milk, egg, chocolate, and citrus fruits.  This elimination diet showed reduction in hyperactivity in 82% of children, with return to normal behavior for 29%.  Subsequent studies have shown mixed results, and the role of the elimination diet in ADHD remains unclear.


Role of the ketogenic diet

As of now, there has not been a study that directly studies the effect of a ketogenic diet on humans with ADHD.  However, there are promising findings from other studies.

A study focused on using the ketogenic diet for reducing seizure frequency in children also demonstrated improvement in ADHD-like symptoms in children without a clinical diagnosis of ADHD.  Specifically, they observed significant improvement in motor functioning, self-help skills, attention, and social skills, suggesting a potential role in alleviating these typical ADHD symptoms.

In animal models of ADHD, a ketogenic diet appears to reduce hyperactive behaviors.  These studies must be interpreted with caution and cannot readily be applied to humans.

While these are promising results, further research is needed to evaluate the effects of a ketogenic diet approach in human subjects.

ADHD brain

Strategies for ADHD

  • Avoid sugar
  • Avoid simple carbs
  • Avoid artificial food coloring
  • Avoid processed foods
  • Do not use food as a distraction
  • Do not use food as a reward or punishment
  • “No” means no. Do not cave
  • Make the healthy choice the easy choice. Reduce barriers – make healthy snacks more available
  • Enforce family mealtime – establish routine, minimize distractions
  • Consider elimination diet to identify food sensitivities
  • Track response to questionable foods
  • Aim for “slow-release” meal in AM for steady glucose throughout the day – e.g. low in carbohydrates, higher protein and fat
  • Consume omega-3 fatty acids – oily fish, supplements, etc. (recommended 300-600 mg/day)


There are many research findings that suggest that metabolic health plays an important role in ADHD, both in causation as well as management.  Unfortunately, we are lacking high-quality, repeatable studies to clearly delineate that relationship.  Given what we know about the rest of brain health, however, it stands to reason that metabolic health should be addressed in the comprehensive management of individuals with ADHD, particularly in regards to nutrition.

Part 5

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