Elsevier

Journal of Affective Disorders

Volume 252, 1 June 2019, Pages 160-173
Journal of Affective Disorders

Review article
Dietary patterns and attention deficit/hyperactivity disorder (ADHD): A systematic review and meta-analysis

https://doi.org/10.1016/j.jad.2019.04.061Get rights and content

Highlights

  • The meta-analysis suggests that a unhealthy diet can increase the risk of ADHD, whereas a healthy diet, would protect against these outcomes.

  • The unhealthy dietary pattern, characterized by the consumption of saturated fat and refined sugar was associated to the risk of hyperactivity or ADHD occurrence.

  • The healthy patterns, characterized by the consumption of fruits, vegetables and whole grains showed a protective effect against hyperactivity or ADHD.

Abstract

Background

The Attention Deficit Hyperactivity Disorder (ADHD) is a neurobiological disorder characterized by persistent symptoms of inattention, impulsivity and hyperactivity. The diet during childhood has been investigated as a factor potentially involved in the ADHD etiology.

Objective

To review systematically the evidence of the association between dietary patterns and ADHD.

Methods

Two independent literature searches were carried out in PubMed, LILACS and PsycINFO databases. The studies included were only those that assessed dietary patterns and ADHD in children and adolescents. Due to heterogeneity between the studies random-effects models were used to pool the estimates.

Results

We included fourteen observational studies (four cohorts, five case-control and five cross-sectional studies). In the pooled analysis, healthy dietary patterns were protective against ADHD (OR: 0.65; 95% CI: 044 – 0.97), while unhealthy dietary patterns were found as risk to ADHD (OR: 1.41; 95% CI: 1.15–1.74). After stratifying the studies by design (cohort/case control or cross-sectional), continent (Europe or Asia/Oceania) and sample size (≥1000 or <1000) the effects remained.

Limitations

Absence of randomized controlled trials at the literature on this subject and scarce evidence from more robust designs, such as cohort and case-control studies.

Conclusion

This study suggests that a diet high in refined sugar and saturated fat can increase the risk, whereas a healthy diet, characterized by high consumption of fruits and vegetables, would protect against ADHD or hyperactivity. Nevertheless, giving the number and the design of most of the studies available in the literature, the current evidence is weak. More studies using longitudinal design need to be performed to reinforce this evidence.

Introduction

The Attention Deficit Hyperactivity Disorder (ADHD) is a neurobiological disorder characterized by persistent symptoms of inattention, impulsivity and hyperactivity (Association AP. 2013). The ADHD begins at childhood and frequently persists until adulthood, causing low educational achievement, as well as cumulative losses throughout life (Barkley and Roizman, 2002), such as family and interpersonal difficulties. The etiology of the disorder is multifactorial, resulting from the interaction between the sex of the child (Arnold, 1996) and genetic and environmental factors, such as intrauterine exposures (Bekkhus et al., 2010) and parent's mental health (Anselmi et al., 2010).

The role of diet in the prevention and/or treatment of ADHD was firstly investigated in the 1980s and 1990s, resulting in a series of studies, mostly experimental, focusing on the effect of additives and sugars on the attention deficit and/or hyperactivity (Wolraich et al., 1995). As a result, dietary therapies were proposed at that time, which mainly included restriction of sugar, additives, food coloring agents and antigens. Later studies showed the protective effect of increased iron intake (Konofal et al., 2008, Konofal et al., 2004), zinc (Akhondzadeh et al., 2004a, Arnold et al., 2005), iodine (Yüksek et al., 2016) and polyunsaturated fatty acids (Johnson et al., 2009, Sinn and Bryan, 2007, Richardson and Montgomery, 2005), and in contrast, adverse effect of excessive ingestion of food coloring agents (Bateman et al., 2004, Rowe and Rowe, 1994), preservatives (McCann et al., 2007) and sugar (Park et al., 2015, Wiles et al., 2009).

Recent studies assessing diet effect on the development of diseases have focused their analysis on dietary patterns, instead of specific nutrients consumption. The analysis of dietary patterns emerged as a complementary approach in the study of the relationship between diet and chronic diseases (Hu, 2002). Thus, the effects of overall diet combinations are evaluated, incorporating complex interactions that occur between nutrients (Hu, 2002). Dietary patterns represent a wider vision of nutrient and food intake and may be more appropriate for the study of the relationship between dietary factors and diseases, (Hu, 2002) as ADHD. Therefore, the purpose of this study was to review systematically the evidence about the relationship between dietary patterns and ADHD. Our hypothesis was that healthy dietary patterns would be protective whereas unhealthy dietary patterns would increase the risk of ADHD.

Section snippets

Methods

In March 2019, we searched indexed articles in PubMed, LILACS and PsycINFO databases using the following combination of descriptors: (“diet” OR “eating pattern” OR “eating patterns” OR “food pattern” OR “food patterns” OR “dietary pattern” OR “dietary patterns” OR “dietary behaviors” OR “dietary behaviours” OR “dietary habits”) AND (“attention deficit hyperactivity disorder” OR “adhd” OR “adh” OR “hyperactive” OR “hyperactivity” OR “inattentive” OR “inattention” OR “hyperactive behaviors” OR

Results

Initially, the 1260 references found in the Pubmed and the 562 found in the other databases (LILACS and PsycINFO) were exported to an EndNote library. A total of 271 duplicates were identified. Next, we selected the titles, resulting in 31 abstracts to be assessed by the reviewer 1 and 44 by the reviewer 2.

After this, reviewer 1 excluded 16 manuscripts based in the following reasons: no assessment of the exposure of interest (like food coloring agents, additives and vitamin supplements) (n

Discussion

In the reviewed papers we found two most frequently consumed dietary patterns, and both indicated dietary effects on ADHD. The healthy patterns characterized predominantly by the consumption of fruits, vegetables and whole grains showed a protective effect against hyperactivity or ADHD, while unhealthy dietary patterns, characterized predominantly by the consumption of saturated fat and refined sugar was associated with increased risk of hyperactivity or ADHD occurrence. However, the

Funding

There was no financing.

Conflict of interest

The authors have no potential conflicts of interest to disclose.

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