CPE Monthly: The Role of Nutrition in ADHD
By Sara Chatfield, MPH, RDN, LDN
Today’s Dietitian
Vol. 25 No. 3 P. 44

CPE Level 3

Take this course and earn 2 CEUs on our Continuing Education Learning Library

Causing symptoms of inattention, hyperactivity, and impulsivity, attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder commonly diagnosed in childhood.1,2 Depending on the presentation of symptoms, patients may be diagnosed with three different types of ADHD: primarily inattentive, primarily hyperactive-impulsive, and combined.1,2

ADHD has a strong genetic component, although multiple environmental risk factors are thought to contribute to its expression.2,3 As of 2015, worldwide prevalence of this disorder is estimated at 7.2% for children under age 18.3 As of 2018, approximately 8.4% of US children were estimated to have a current diagnosis of ADHD, with males being diagnosed about twice as often as females.3 Although ADHD is diagnosed at an average age of about 6 years, ADHD symptoms—particularly those related to inattention—can continue into adolescence and adulthood.2,3

Common psychiatric comorbidities of ADHD include depression, anxiety disorders, bipolar disorder, oppositional defiant disorder, eating disorders, and substance abuse disorders.2 ADHD can cause problems in social and academic functioning and may increase the risk of multiple health conditions, including obesity, hypertension, and diabetes.2 Standard treatments for ADHD include behavior therapy and medication.1,3,4 Medications can include central nervous system stimulants—which are most widely used—and/or nonstimulants.1,3,4

Nutrition has long been of interest in the management of ADHD. Some studies have found that patients with ADHD have lower quality diets or lower blood levels of nutrients compared with those without the disorder.5-12 Research generally has focused on eliminating foods or additives thought to trigger symptoms or adding nutrients, such as essential fatty acids (EFAs), vitamins and minerals, or other supplements such as probiotics and herbs. Limitations in the number and quality of recent studies contribute to difficulties in reaching conclusions about the usefulness of many of these nutrition interventions.

This continuing education course details the relationship between ADHD and nutrition status and discusses the efficacy of various nutrition strategies for managing symptoms.

Dietary Intake, Lifestyle, and ADHD
Although research in the area is limited, some studies have found a link between health behaviors and ADHD. Various elements of diet and other lifestyle factors differ among participants with ADHD and controls.6,11,13,14

Overall Diet Quality
Some observational studies have found associations between diet and ADHD diagnosis. Various dietary patterns classified as healthful, such as those higher in fish, white meat, other nutrient-rich foods, carbohydrates, fatty acids, protein, and minerals, have been linked with lower odds of having ADHD.10,12 A population-based survey of 5,200 fifth-grade Canadian students found that children in the highest tertile for diet quality determined by the Diet Quality Index-International had a significantly lower number of health care visits for ADHD.11 Conversely, less healthful dietary patterns have been positively associated with an ADHD diagnosis. These include dietary intakes with lower adherence to a Mediterranean-type diet and those with lower intakes of fruits and vegetables, dairy, fatty fish, pasta and rice, and protein, and higher intakes of snack foods, processed meats, refined grains, sugar, and caffeine, as well as a higher frequency of unhealthful habits such as breakfast skipping and fast food consumption.5,8,10,12

Factors that can impact the diet quality of individuals with ADHD include medication, symptoms, and diet education. Stimulant medications, especially the long-acting variety, are associated with appetite suppression.15

A cross-sectional study of Spanish children found that children with ADHD being treated with long-acting methylphenidate, a common first-line stimulant medication, had lower calorie intakes overall and at midmorning snack, lunch, and afternoon snack, and lower intakes of macronutrients and a variety of micronutrients than children without ADHD. A longitudinal study of 3,680 children aged 6 to 10 found a correlation between more ADHD symptoms at age 6 and poorer diet quality (as reported via food frequency questionnaires) at age 8; however, no link was found between diet quality at age 8 and more ADHD symptoms at age 10. Researchers theorized that ADHD symptoms may lead to impulsive eating of more palatable foods rather than poor dietary choices contributing to ADHD symptoms.7 However, in a randomized controlled trial (RCT) of 106 youth aged 5 to 14 with ADHD treated at an Iranian psychiatric clinic, education provided to the parents of the treatment group on recommended foods (fruits and vegetables, whole grains, dairy) and food items to limit (sugar, soft drinks, sauces), along with the stimulant medication provided to both participants and controls, was found to significantly decrease scores for inattentiveness, but not those of hyperactivity or impulsivity.16

Sugar and Caffeine Intake and Other Lifestyle Factors
There have been conflicting results in the research on sugar intake and ADHD.17,18 One study of a Brazilian cohort assessed at ages 6 and 11 for sugar intake and ADHD diagnosis found that, while mean levels of sugar consumption were overall far above recommended levels at both ages for children with and without ADHD, the only association found between sugar consumption and ADHD diagnosis was for 6-year-old boys. The researchers theorized that increased sugar consumption may be a consequence rather than a cause of ADHD.18 Increased sweetened beverage consumption was, however, associated with significantly increased odds of being at risk of inattention and hyperactivity in a study of the health behaviors of 1,649 US middle schoolers, although the researchers noted that ADHD diagnoses weren’t determined, and the 24-hour recalls may not have reflected usual intake.19

Caffeine use has been associated with ADHD in some studies but not others, and there’s conflicting data on caffeine’s positive or negative effects on ADHD symptoms.20,21 In one study of 302 adolescents aged 12 to 14, afternoon and evening consumption of at least one caffeinated beverage was linked with reported sleep problems.20,21 Sleep problems have been correlated with ADHD.20,22

In addition to dietary risk factors, children with ADHD have been found in some research to have other lifestyle risk factors, many of which are interrelated, including more screen time and less physical activity than children without the disorder.11,20,22 Physical activity levels in children and adolescents with ADHD have been associated with fewer ADHD symptoms in adulthood.23

Although several of these studies point to a trend of lower diet quality and other lifestyle risks in ADHD, none of them establish causality due to their observational design.

ADHD and Body Composition
Some research has found associations between ADHD and overweight or obesity in youth and adults; this link may be stronger for adult obesity, although the number of studies in adults is more limited.6,13,14,24,25 A meta-analysis of 41 studies on the prevalence of obesity in individuals with ADHD found that ADHD was significantly associated overall with obesity in both children and adults, particularly in adults.14 However, not all studies found a link, and another meta-analysis determined that less than one-third of the studies it analyzed had found a statistically significant association between ADHD and overweight or obesity.14,25

Much of the research on youth reflects an unclear relationship between ADHD diagnosis and weight status. Some observational studies have found that ADHD diagnosis and BMI were unrelated in children.25 Others have found associations between ADHD diagnosis and higher BMI, although not all have reached significance.24,25

Use of stimulant medications for ADHD may impact the link between ADHD and weight status; they’ve been associated with growth delays and lower BMI in children and, in some research, with a lower prevalence of obesity.13,15,24,26,27 However, some studies have found that childhood stimulant use was linked with BMI increases in adolescence. One longitudinal study in children with ADHD found a negative association between early (before first grade) stimulant use and increases in BMI up until fifth grade, but a positive association between stimulant use between first and third grade and BMI increases between fifth and eighth grade. In this study, the growth rates of children with unmedicated ADHD didn’t differ significantly from those of children without ADHD.13 A longitudinal study of 163,820 US youth aged 3 to 18 found that unmedicated ADHD was associated with a higher BMI than not having ADHD or having ADHD treated with stimulants, but researchers also found evidence of a BMI rebound after initial growth delays in adolescent participants taking stimulants.26

Moreover, there’s observational data in youth linking the use of stimulant medication to lower bone density.27 A cross-sectional analysis of 2005–2010 NHANES data of 159 8- to 20-year-old participants using stimulants and 6,330 nonusers of the same age range found that participants taking stimulants for at least three months had significantly lower lumbar spine bone mineral density and bone mineral content and significantly lower femoral neck bone mineral density than nonusers.27 Although causality can’t be proven, and there are other factors affecting bone mass, it’s theorized that the increased availability of the neurotransmitter norepinephrine from stimulant use may decrease bone accrual, which could lead to an increased risk of fractures and osteoporosis.27

Although there’s some evidence of a correlation between ADHD and overweight or obesity, the relationship is unclear, especially in youth. Theories proposed for a relationship, which has been suggested to be bidirectional, between ADHD and overweight or obesity include difficulty with impulsivity or self-regulation, such as difficulty maintaining regular eating patterns, inattention (such as not paying attention to cues of satiety), lower physical activity levels, and sleep disruption.14,24-26 Stimulant medications initially may reduce growth rates and BMI in treated children, with possible increases later in adolescence.

Disordered Eating
Although there’s limited research in this area, some studies have found a link between a childhood ADHD diagnosis and later disordered eating or an eating disorder diagnosis, while others have found none.28,29 Due to the variations in participants, types of eating disorders studied, and study designs, it’s difficult to determine association.28

A review of studies on ADHD and eating disorders found that the prevalence of ADHD in eating disorder patients varied widely, from 1.6% to 18%.28 ADHD diagnosis was reported more often with the binge eating/purging subtype of anorexia nervosa than the restrictive subtype.28 One study on binge eating disorder found that 1.7% of patients had ADHD.28 Two studies on bulimia nervosa found that, on average, 22.5% of patients had childhood ADHD.28 In a prospective study of 1,165 adults aged 18 to 70 being treated at an eating disorder clinic, almost one-third of patients screened positive for recent (past six months) symptoms of ADHD, although a childhood ADHD diagnosis wasn’t determined.29 Researchers noted that the shared comorbidities and overlap in symptoms of ADHD and eating disorders may factor into the links between these disorders.28,29

Elimination Diets
Some research indicates that limiting certain foods and dietary additives may improve symptoms of ADHD. Studies generally have focused on limiting food colorings and sometimes other preservatives, or on more restricted diets that eliminate multiple foods in an attempt to identify food sensitivities.

Pediatrician Benjamin Feingold initially developed the Feingold diet in the 1970s to treat patients with allergies and later expanded its use to those with ADHD. Interestingly, ADHD has been associated with allergic diseases, including allergic rhinitis, asthma, and atopic dermatitis, although the relationship is unclear.30-34 The Feingold diet eliminates food colorings and certain preservatives in an attempt to reduce ADHD symptoms that may be worsened by these ingredients.35,36 The diet, generally tried for a two- to four-week period, is less restricted and less likely to be nutritionally inadequate than stricter elimination diets.35 Some meta-analyses have found that these additive-free diets had significant but small effects on ADHD symptoms, although some participants were preselected for suspected food sensitivities.32 Other studies have found that food colorings were linked with hyperactive behavior in children regardless of ADHD diagnosis.32,37

Most food elimination diets used in ADHD studies, also called “few foods” diets, have strictly limited participants to foods considered low risk for allergies or sensitivities; for example, one study’s diet included lamb, chicken, potatoes, rice, bananas, apples, and brassica vegetables.36 The next step in the elimination protocol, after about five weeks, is to reintroduce foods to those who responded positively, a process which is noted to take up to 11/2 years.38 These diets are intended to identify food sensitivities to make personalized diet recommendations.36,38

While elimination diets have been associated in some studies with improvement in participants’ ADHD symptoms, their restrictiveness makes them difficult to manage and hard for children to tolerate, and they can lead to nutrient deficiencies if used long term.35-37 There’s a lack of recent double-blinded studies with fully controlled elimination diet protocols, and the effects found in unblinded elimination diet studies may be unreliable due to bias from raters.32,35,37,39 One meta-analysis of elimination diet studies found that when analysis was restricted to “probably blinded” studies, effects on symptoms were small or greatly decreased.32,37,39 The meta-analysis also noted that the larger effects of elimination diets, excluding food coloring and other additives, often were found in participants selected for suspected food sensitivities.39 Researchers theorize that a small subset of children with ADHD may benefit from the use of elimination diets to identify food sensitivities.35 These diets must be overseen by a dietitian for nutritional adequacy.35

Nutrient Levels in ADHD
Some studies have noted lower levels of nutrients in participants with ADHD compared with controls, including reduced blood levels of iron and ferritin and hemoglobin, lower levels of zinc, magnesium, and vitamin D, and decreased levels of omega-3 fatty acids, particularly DHA, or a lower ratio of omega-3 to omega-6 fatty acids.8,12,17,33,34,40-46 Levels of copper have been noted to be lower in those with ADHD compared with controls in some studies but higher or similar in other studies.33,42 Research on selenium levels in participants with ADHD seems to be scarce; in one study, no significant differences were found between children with ADHD and controls.42 Limitations of these studies include varying study participant characteristics and nutrient intakes, potential impacts of treatments, and different methods of measurement. Researchers have theorized that lower nutrient levels in individuals with ADHD may result from reduced appetite due to ADHD medication or other factors.42 Diet quality also may play a role.

Several nutrients, some of which have been found to be altered in ADHD, are involved in brain function. B vitamins, especially vitamins B6, B9, and B12, are involved in neurotransmitter production, as are iron and zinc.6,34,37,40 Iron and zinc also are essential to fatty acid transport, as is carnitine, a compound made from amino acids.37

Dietary Supplements
Due to the associations between lower nutrient levels and ADHD or concerns about using medications, many families are interested in alternative or complementary treatments, including nutrient or herbal supplements.4,40 A national survey found that approximately 10% of children aged 4 to 17 with ADHD had taken dietary supplements for the condition within the year.4 Supplements researched for their effects on ADHD include nutrients found to be lower in those with the disorder or those thought to impact brain function, including vitamins and minerals (individually or within broad-spectrum formulas), EFAs, and particularly omega-3 fatty acids, herbal supplements, and probiotics.

Micronutrient Supplements
Research on the effects of micronutrient supplementation, including supplements of single and multiple nutrients, on participants’ ADHD symptoms has found mixed results. The limited pool of research, small sample sizes, and wide variation in subject characteristics and types and doses of supplements make conclusions about efficacy difficult.

Several RCTs in children with ADHD have found that multiple-nutrient supplements, including varying combinations of vitamins and minerals (one which also included amino acids), some with a large number of capsules, have significantly improved symptoms over placebo.9,47 One of the studies also found small increases in diversity of the treatment group’s microbiome over controls, although these didn’t reach significance.47 One study with an on-again-off-again supplement treatment found small to large effect sizes on children’s symptoms according to parent, teacher, clinician, and self-ratings; however, this small study was unblinded and uncontrolled.48 Not all studies of micronutrient supplements have found positive results in children with ADHD; a review of several studies of megadoses (many times above Danish Recommended Daily Allowances) of vitamin supplements, including B vitamins and vitamin C, given to children with ADHD found no significant effects on their symptoms, and two of these studies found elevated liver enzymes in children given a combination of vitamins B3, B5, B6, and C.37

Studies of micronutrient supplements in adults with ADHD are scarcer. One trial in New Zealand, in which 80 adults with ADHD were given either a broad-spectrum multivitamin and mineral formula or a placebo, found that the treatment significantly improved self and observer (but not clinician) ratings of symptoms and significantly increased blood levels of vitamin D, vitamin B12, and folic acid.49

There’s also a scarcity of research on single-nutrient supplementation for ADHD, particularly for vitamins. In a review of three small RCTs providing vitamin D to children with ADHD in addition to the stimulant methylphenidate, all found significantly improved symptoms, by parent ratings, with vitamin D over placebo. One of the studies noted that some participants began the study with insufficient levels of vitamin D.9

The limited studies on mineral supplementation in children with ADHD have found mixed results. In a review of three small RCTs, two of the studies found that providing zinc supplements to boys with ADHD, in addition to the stimulant medications given to both groups, improved their inattention scores more than placebo, while one study found no significant effects.9 In another review of studies on zinc supplementation, two of three double-blinded RCTs found that high doses of zinc given to children with ADHD had significant effects on their symptoms; the studies with positive results, however, were done in Iran and Turkey, where zinc deficiency rates are suspected to be higher than in the United States.37,40 In a review of two studies on iron supplementation, an uncontrolled study with 14 boys aged 7 to 11 with ADHD found that the supplements had a significant effect on ADHD symptoms, while the RCT found a trend toward improvement that didn’t reach significance.37 A review of two studies on magnesium supplementation found that, while both studies reported improvement in ADHD symptoms, they used unknown rating scales to measure symptoms and had issues with randomization.37

A limited number of studies on other nutrients given to participants with ADHD include a review of three trials of carnitine supplements, one of which found a positive impact on symptoms with small to medium effect sizes, while the other two didn’t find significant effects.37

While some of the studies on micronutrient supplementation have found positive effects on ADHD symptoms, particularly those that used multiple micronutrient formulas or treated participants who may have had deficiencies, the limited research available doesn’t support clear-cut recommendations for micronutrient supplement use in individuals with ADHD without confirmed deficiencies.

Essential Fatty Acid and Phospholipid Supplements
Findings that some individuals with ADHD have lower levels of omega-3 fatty acids or higher omega-6 to omega-3 fatty acid ratios have led to interest in supplementation for those with the condition. Omega-3 fatty acids are critical in brain development and function; DHA, in particular, has been found to have a role in neural transmission and in the function of dopamine, a neurotransmitter involved in ADHD symptoms.33,46,50 Omega-3 fatty acids also have anti-inflammatory and antioxidant effects; increased omega-3 levels have been found to reduce oxidative stress, which may be higher in ADHD, whereas a higher omega-6 to omega-3 fatty acid ratio may promote neuroinflammation.40,43 Studies of EFAs in ADHD generally have involved supplements of omega-3 fatty acids and sometimes omega-6 fatty acids, or a combination. Some also have included phosphatidylserine, a phospholipid involved in cellular structure and fatty acid absorption.

Multiple studies have found significant improvement in the ADHD symptoms of youth given omega-3 fatty acid supplements.36,37 A review of 11 RCTs using omega-3 fatty acids, omega-6 fatty acids, or a combination, found that the supplements significantly improved the ADHD symptoms of participants with a small effect size.39 However, not all studies have found positive results. Another review of RCTs, some overlapping with other reviews, found that of 20 studies using EFA supplements with omega-3 fatty acids, omega-6 fatty acids, or a combination, including a few with added vitamins or phosphatidylserine, 13 noted various significant improvements in ADHD symptoms while seven did not.9 In a review of 25 RCTs of those aged 4 to 18 with ADHD given omega-3 fatty acid supplements either as the sole therapy or in addition to medication, 13 found that the supplements had positive effects on ADHD symptoms, while the other 12 found no significant changes. Certain attributes of the studies with positive effects were identified, including having at least 50 participants and providing both EPA and DHA (when this was specified) for a period of at least 15 weeks.51 A meta-analysis of eight RCTs using doses varying from 2.7 to 640 mg of DHA and 80 to 650 mg of EPA found that the supplements improved parental but not teacher ratings of both inattentive and overall ADHD symptoms and some cognitive measures; however, only studies with EPA doses of at least 500 mg found significant improvements in hyperactive symptoms.43 Other meta-analyses also have found a significant association between EPA dose and efficacy.40 One review of 16 studies determined that those providing EFAs in the form of plant oils found no significant effects on ADHD symptoms.37 Overall, limitations in the research include variations in the number of participants, types and doses of EFAs, treatment lengths, and the use of plant oils in some control groups.36,37,51

In one small RCT (n=36), 100 mg of phosphatidylserine alone was given to children with ADHD for eight weeks, and the children’s symptoms improved (according to clinician ratings) over placebo.9

Overall, there’s evidence for EFA supplements having small but significant effects on ADHD symptoms, although it’s difficult to determine specific recommendations due to the varying types and doses of supplements used in studies.

Herbal Supplements
There’s some evidence of decreased antioxidant enzyme activity and increased stress markers in individuals with ADHD.33,40 Some herbs with antioxidant activity have been studied for effects on ADHD symptoms with mixed findings. While some studies have noted benefits, there’s a lack of published research on using herbs for ADHD.

Among this limited research, the most frequently studied herbs seem to be those containing flavonoids or other polyphenols, plant compounds with significant antioxidant and anti-inflammatory properties. In an RCT of 61 children with ADHD taking either a 1 mg/kg/day extract of pycnogenol, a polyphenol, or a placebo for one month, there was evidence of lower oxidative stress in the treatment group, as well as significantly improved ADHD symptoms on one teacher rating scale.33,40 A double-blinded RCT using 80 to 120 mg/day of another polyphenol, Ginkgo biloba extract, given to 50 patients with ADHD for six weeks found that the supplement was less effective than the stimulant medication methylphenidate.9,33,40,52 However, in another relatively small RCT, the same dose range of ginkgo given to children with ADHD in addition to methylphenidate was found to improve inattention and overall parent ratings of symptoms more than placebo given with the medication.9 In addition, a higher dose of up to 240 mg of Ginkgo biloba extract, given to 20 children for three to five weeks, was found to improve ADHD symptoms in an open study.33,52 In an RCT with 54 participants, 900 mg of St. John’s wort, another polyphenolic compound, given for eight weeks didn’t significantly improve ADHD symptoms over placebo.33,40 However, an RCT with 34 participants with ADHD found that the flavonoid herb passionflower, given at 0.4 mg/kg twice daily over eight weeks, improved ADHD symptoms as well as methylphenidate.33

Korean red ginseng, containing ginsenoside saponins, another type of plant compound with antioxidant and anti-inflammatory properties, was given to children with ADHD at a dose of 1 g twice daily for eight weeks in another small RCT; the children’s symptoms of inattention and hyperactivity significantly improved over placebo.9

Despite some positive results in these relatively small studies, researchers have noted that findings on herbal supplements for ADHD are considered preliminary due to a lack of consistent research and unclear mechanisms of action.9

The Microbiome and ADHD
Some researchers have suggested that the apparent link between ADHD and diet is mediated through the gut microbiome, including food sensitivities.32,53 Disturbance of the microbiome in early life can impact neurodevelopment, and there’s evidence that the microbiome influences neurotransmitter function, supporting a connection between the gut microbiome and neuropsychological disorders such as ADHD.30,44 Some studies have found differences in the composition of the microbiome of patients with ADHD and controls, but the participants, study designs, and results have varied too widely to draw specific conclusions.44 This is an emerging area of research on ADHD.48,54

There are a limited number of studies on probiotics, which may affect the microbiome and ADHD. One small RCT found that infants who received Lactobacillus rhamnosus GG rather than placebo from 0 to 6 months of age were less likely to be diagnosed with ADHD at age 13 and that children who were later diagnosed with ADHD had, on average, lower numbers of fecal Bifidobacterium species during their first six months of life.55 An RCT of 32 youth aged 4 to 17 with ADHD in Slovenia, 18 of whom received one capsule once daily of the probiotic Lactobacillus rhamnosus GG, while the others received a placebo for three months, found that the treated group had significant improvements in self-reported ADHD symptoms and health-related quality of life over the placebo group. However, parental and teacher reports and psychometric tests didn’t find significant differences.56

Recommendations for RDs in Practice
Observational data suggest that individuals with ADHD tend to have diets lower in beneficial nutrients and higher in sugar than those without the disorder. RDs working with clients or patients with ADHD should tailor diet recommendations to individual needs, taking into account challenges related to symptoms and treatment that may impact nutrition goals. For example, stimulant medications may affect appetite, particularly during the day, and RDs can help clients and families find ways to ensure adequate nutrition.

When working with clients on nutrition goals and planning, RDs should be aware of how ADHD symptoms such as impulsivity and inattention may impact food choices and the ability to plan meals and snacks. RDs also should assess other lifestyle risk factors related to ADHD that can impact nutrition and weight status, such as physical activity level and sleep habits.

Since ADHD is associated with a variety of other health conditions, including other psychological disorders, chronic diseases, and allergic conditions, these health issues also may impact nutrition recommendations. RDs should closely monitor clients undertaking elimination of foods or additives due to suspected food sensitivities, particularly children, for adequate nutrition intake.

Screening for micronutrient status may benefit individuals with ADHD, particularly if diet history reveals potential deficiencies, taking note of those that have been identified in research as being of concern, such as iron, zinc, and vitamin D. Any recommendations for supplementation of micronutrients, EFAs, and probiotics should be based on individual needs. Use of herbal supplements should be approached with caution due to the limited research available.

RDs working with individuals with ADHD should communicate any diet recommendations and nutrition goals to other health care providers involved in their care. They also should notify providers of any discussion of supplement use, and interactions with medications should be considered.

— Sara Chatfield, MPH, RDN, LDN, is a Chicago-based freelance nutrition writer who has practiced dietetics in clinical and community settings.

Learning Objectives
After completing this continuing education course, nutrition professionals should be better able to:
1. Distinguish nutrition parameters related to ADHD.
2. Assess the potential impact of ADHD symptoms or treatments on nutrition status.
3. Counsel patients on possible nutrition interventions for ADHD symptoms.
4. Evaluate potential benefits and risks of common nutrition interventions for ADHD.

Exam
1. Which (approximate) percentage of US children had a current diagnosis of ADHD as of 2018?
a. 4%
b. 8%
c. 10%
d. 12%

2. One theory for the finding, in observational studies, that children with ADHD have lower quality diets is that they may make poorer dietary choices due to which of the following?
a. Increased appetite
b. Higher physical activity levels
c. Impulsivity
d. Greater access to snacks

3. The link between overweight, obesity, and ADHD appears to be stronger for which group?
a. Individuals taking medication
b. Children
c. Adolescents
d. Adults

4. In a large prospective study of adults being treated at an eating disorder clinic, which fraction screened positive for recent ADHD symptoms?
a. One-fifth
b. One-fourth
c. One-third
d. One-half

5. In some studies, food colorings have been associated with which symptom in children regardless of ADHD status?
a. Hyperactivity
b. Inattention
c. Impulsivity
d. Sleep problems

6. In the elimination diet protocols that generally have been used in studies of children with ADHD, the food reintroduction period has been noted to take up to what amount of time?
a. 6 months
b. 1 year
c. 11/2 years
d. 2 years

7. Which two minerals are important in neurotransmitter production and fatty acid transport and have been found to be low in some studies of individuals with ADHD?
a. Iron and zinc
b. Calcium and magnesium
c. Copper and selenium
d. Potassium and phosphorus

8. According to a national survey, what percentage of children with ADHD had taken dietary supplements within the year?
a. 5%
b. 10%
c. 15%
d. 20%

9. In studies on the impact of omega-3 fatty acid supplements on ADHD symptoms, which factor has been associated with positive effects?
a. Shorter treatment period
b. Use of plant oils
c. Smaller number of participants
d. Higher EPA dosage

10. What is one of the limitations of research on supplements for ADHD?
a. Use of the same supplements
b. Small sample sizes
c. Standardized dosages
d. Use of placebos

References
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3. About ADHD — overview. Children and Adults with Attention-Deficit/Hyperactivity Disorder (CHADD) website. https://chadd.org/about-adhd/overview/. Updated 2022. Accessed April 1, 2022.

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8. Ríos-Hernández A, Alda JA, Farran-Codina A, Ferreira-García E, Izquierdo-Pulido M. The Mediterranean diet and ADHD in children and adolescents. Pediatrics. 2017;139(2):e20162027.

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12. Zhou F, Wu F, Zou S, Chen Y, Feng C, Fan G. Dietary, nutrient patterns and blood essential elements in Chinese children with ADHD. Nutrients. 2016;8(6):352.

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15. Durá-Travé T, Gallinas-Victoriano F. Caloric and nutrient intake in children with attention deficit hyperactivity disorder treated with extended-release methylphenidate: analysis of a cross-sectional nutrition survey. JRSM Open. 2014;5(2):2042533313517690.

16. Ghanizadeh A, Haddad B. The effect of dietary education on ADHD, a randomized controlled clinical trial. Ann Gen Psychiatry. 2015;14:12.

17. Cruchet S, Lucero Y, Cornejo V. Truths, myths and needs of special diets: attention-deficit/hyperactivity disorder, autism, non-celiac gluten sensitivity, and vegetarianism. Ann Nutr Metab. 2016;68(Suppl 1):43-50.

18. Del-Ponte B, Anselmi L, Assunção MCF, et al. Sugar consumption and attention-deficit/hyperactivity disorder (ADHD): a birth cohort study. J Affect Disord. 2019;243:290-296.

19. Schwartz DL, Gilstad-Hayden K, Carroll-Scott A, et al. Energy drinks and youth self-reported hyperactivity/inattention symptoms. Acad Pediatr. 2015;15(3):297-304.

20. Cusick CN, Langberg JM, Breaux R, Green CD, Becker SP. Caffeine use and associations with sleep in adolescents with and without ADHD. J Pediatr Psychol. 2020;45(6):643-653.

21. Ágoston C, Urbán R, Horváth Z, van den Brink W, Demetrovics Z. Self-medication of ADHD symptoms: does caffeine have a role? Front Psychiatry. 2022;13:813545.

22. Holton KF, Nigg JT. The association of lifestyle factors and ADHD in children. J Atten Disord. 2020;24(11):1511-1520.

23. Christiansen L, Beck MM, Bilenberg N, Wienecke J, Astrup A, Lundbye-Jensen J. Effects of exercise on cognitive performance in children and adolescents with ADHD: potential mechanisms and evidence-based recommendations. J Clin Med. 2019;8(6):841.

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