How diet affects ADHD symptoms: Updated patient guidance for clinicians

By Anastasia Climan, RDN, CD-N | Fact-checked by Barbara Bekiesz
Published January 9, 2024

Key Takeaways

  • Dietary patterns that emphasize nutrient-rich, unprocessed foods appear protective against ADHD symptoms.

  • Micronutrients and probiotics may help with ADHD, but there’s not enough evidence to support supplementation without a deficiency.

  • Doctors can cautiously suggest an elimination diet to determine if an individual has specific dietary triggers.

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurobiological conditions in the world. It typically emerges in childhood and may persist through adulthood, causing symptoms like hyperactivity, short attention span, and impulsive behavior. 

Despite assumptions about ADHD and nutrition, clinicians don’t have clear dietary guidelines to help improve patients’ lives. Although certain ways of eating are linked to ADHD symptoms, such as diets high in processed foods and sweets, a lack of strong evidence makes it difficult to recommend supplementation or generalized restrictive diets across the board. 

Here’s what we know about the way diet affects ADHD symptoms, along with a specific therapeutic protocol that can help offer tailored solutions.

Micronutrients and supplements

A systematic review of the role of iron and zinc in ADHD has identified the potential benefits of these micronutrients in reducing ADHD symptoms.[] Both minerals act as dopamine reuptake inhibitors, with similar targets as stimulant medications used to treat ADHD. 

Children with low iron stores at baseline benefit from iron supplementation, but the evidence isn’t as convincing to supplement kids without a deficiency.

The importance of correcting a zinc deficiency seems to be stronger, and thus adequate intake of dietary zinc should be encouraged. There’s also growing interest in polyunsaturated fats, vitamin D, and probiotics to address underlying inflammation and gut dysbiosis that may contribute to the progression of ADHD.

Currently, the evidence best supports supplementation with vitamin D, but only in the presence of a deficiency, according to a review in Nutrients of dietary patterns in ADHD.[]

Harmful foods and additives

The Nutrients review found that dietary patterns described as being high in empty calories and processed foods are associated with the risk of ADHD, whereas diets rich in fruits, vegetables, and micronutrients (such as the Mediterranean diet, DASH diet, and vegetarian diet) are inversely associated with the disorder.

Related: The secret ingredient to the Mediterranean diet

In fact, as the researchers noted, “The Western pattern, rich in red and processed meats, refined cereal grains, soft drinks, and hydrogenated fats, was shown to increase the risk of ADHD by 92%.”

Sugar, specifically, has become almost synonymous with hyperactivity. But interestingly, the research isn’t as clear-cut as one might expect. Studies suggest a connection between sugar intake and the prevalence of ADHD in 6-year-old boys.[] However, investigators suspect that higher sugar consumption in older children with ADHD may be a “consequence rather than a determinant of the disorder.”

Dietary interventions

Despite important contributions from studies on dietary patterns and ADHD, there are some key problems that limit the value of this data. Dietary patterns are complex and require arbitrary decisions and interpretation. Dietary pattern research tends to focus on specific populations, which isn’t always scalable to other groups. In addition, observations about dietary patterns fail to identify specific triggers, leading to potentially unnecessary restrictions and rules.

Elimination diets, such as the few-foods diet, or the oligoantigenic diet, can help identify specific food hypersensitivities or allergies that may exacerbate ADHD symptoms. These diets start by eliminating most foods, gradually reintroducing them one by one. Although tedious, undergoing an elimination diet can be highly effective in pinpointing problematic foods, according to researchers writing in Current Nutrition Reports.[] Up to 60% of participants have achieved significant improvements in ADHD after 4 weeks of adhering to the few-foods diet.

Current Nutrition Reports cites a study done at specialized healthcare facilities in the Netherlands, in which the few-foods diet was used for children with ADHD and oppositional disorders for 5 weeks. The results showed clinically relevant effects, including a reduced need for medication.

As current research cannot confirm a cause-and-effect relationship between diet and ADHD, elimination diets open the door for tailored recommendations. However, practitioners must use caution when prescribing an elimination diet due to the potential for nutrient deficiencies and growth impacts in children.

What this means for you

As a best practice, clinicians should inquire about their ADHD patients’ diets and encourage healthy eating; they can also test for micronutrient deficiencies. Although instituting an elimination diet can be quite rigorous—requiring medical supervision and training or support for the patient and family—elimination diets have the potential to help a large percentage of patients with ADHD reduce associated symptoms and reliance on medication.

Read Next: Are emulsifiers harming your patients' health?

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