Lower Adherence to Mediterranean Diet Linked to ADHD

Pam Harrison

February 09, 2017

A new cross-sectional study shows a higher risk for attention-deficit/hyperactivity disorder (ADHD) among children and adolescents who are less adherent to a Mediterranean diet than those who are more adherent to the diet.

"Previous studies done in other countries showed that low-quality diets are persistently associated with a higher risk of ADHD [but] no studies had been done regarding the Mediterranean diet and ADHD," senior author Maria Izquierdo-Pulido, PharmD, PhD, University of Barcelona, Spain, told Medscape Medical News.

They found the association between low adherence to the Mediterranean diet and the odds of an ADHD diagnosis remained significant after adjusting for confounding variables such as body mass index, level of physical activity, maternal smoking during pregnancy, maternal and paternal education level, biological father living with family, and parental divorce, she added.

"If we get financial funding, we will eventually carry our study [further] to explore the value of a healthy balanced diet like our Mediterranean diet in ADHD children and adolescents," Dr Izquierdo-Pulido said.

The study was published online January 30 in Pediatrics.

The study included 60 children and adolescents who had been newly diagnosed with ADHD and 60 sex- and age-matched control participants (age for all participants, 6 to 16 years). The two groups were compared with respect to dietary intake and adherence to a Mediterranean diet.

"Food consumption and nutrient intake were measured by a validated food-frequency questionnaire (FFQ) administered by a trained interviewer," the investigators write. For each of the 45 items listed on the FFQ, participants recorded their usual pattern of consumption. Responses could range from consuming a listed item never or less than once a month to consuming the item six or more times a day. Investigators also conducted a 24-hour "recall" interview by telephone.

Adherence to the KIDMED test helped determine adherence to the Mediterranean diet. Dr Izquierdo-Pulido explained that the KIDMED test is a simple way to evaluate adherence to any healthy diet, with higher scores signifying higher levels of adherence.

Significantly Lower Scores

"Children and adolescents with ADHD showed statistically significant lower scores of adherence to a Mediterranean diet than controls," the investigators report. For example, compared to control participants, those who had been newly diagnosed with ADHD were significantly less likely to consume a second serving of fruit every day. They were also less likely to consume fresh or cooked vegetables once or more each day or pasta or rice almost every day.

"In addition, the percentage of subjects with ADHD who ate more frequently at a fast-food restaurant was higher than that of controls," the study authors note. A significantly higher percentage of patients with ADHD skipped breakfast in comparison with control participants, they add.

Both groups consumed fish, dairy products, or baked goods with relatively equal frequency.

Table. KIDMED Score and Frequency of Adherence to Components of the Mediterranean Diet

Endpoint ADHD Patients Non-ADHD Control Persons P Value
Mean KIDMED score total (%) 6.2 8.1 .001
KIDMED test (% yes)  
2nd serving of fruit daily (%) 20 38.3 .027
Fresh or cooked vegetables daily (%) 35 58.3 .010
Fresh or cooked vegetables more than once a day (%) 31.7 61.7 <.001
Fast-food more than once a week (%) 20.0 1.7 <.001
Pasta or rice almost every day (%) 55 85 <.001
No breakfast (%) 6.7 0 .042


No statistical difference was observed in the consumption of white fish between participants with ADHD and control persons. On the other hand, there was a significant difference in fatty fish consumption between the two groups; those with ADHD consumed, on average, 7.5 g/day of blue fish compared with 8.8 g/day for non-ADHD control persons.

Similarly, patients with ADHD consumed approximately twice as much sugar and candy, at 4.7 g/day, compared to non-ADHD participants, at 2.4 g/day. ADHD patients also consumed more noncola soft drinks (41.1 vs 22 g/day) as well as cola beverages (17.2 g/day vs 9.2 g/day).

Reverse Causation

Dr Izquierdo-Pulido and colleagues point out that reverse causation cannot be ruled out as a possible explanation for the observed relationship between diet and the diagnosis of ADHD in the current study.

"In other words, individuals with ADHD may make poor dietary choices (ie, fat-rich or sugar-rich snack foods) to balance their impulsivity traits or emotional distress," she explained to Medscape Medical News. This observation seems to have been borne out, inasmuch as participants with ADHD consumed significantly more sugary foods and beverages than control persons.

A poor-quality diet may lead to deficiencies in essential nutrients, such as iron, zinc, magnesium, and omega-3 fatty acids, all of which contribute to healthy cognitive and physical growth, she said.

"These nutrients also seem to play an essential role in the etiology of ADHD," Dr Izquierdo-Pulido added. "And we believe this may be a vicious cycle: that the impulsiveness of ADHD subjects could lead to worse food choices, a lower-quality diet, and a low intake of certain nutrients, and eventually lead to certain subclinical deficiencies and, hence, worsen ADHD symptoms," she explained.

Dr Izquierdo-Pulido concluded that they would like to see pediatricians delve more deeply into the dietary and sleep patterns of their patients and that they "strongly recommend" a healthy, well-balanced diet, daily exercise, and enough sleep to optimize health for children and adolescents.

Family Dinner

Asked by Medscape Medical News to comment on the study, Scott Benson, MD, a child psychiatrist in private practice in Pensacola, Florida, said that it may be too easy to blame processed food and especially sugar as the cause of ADHD — as many parents do — because there is little evidence to support a causative role of fast food in the etiology of ADHD, although a lot of research implicates fast food in the etiology of childhood obesity.

Given that ADHD is almost certainly present in children in all cultures, Dr Benson felt that the process of preparing and serving nutritious, healthy meals – as good adherence to the Mediterranean diet would require – is more a sign that parents are thoughtful and organized enough to ensure that their child consumes a good diet.

"What this study shows me is that there are some families who are well organized, who can fix dinner at home and have family dinner time, where they all sit around the table and talk about their day, and in cultures where families are well organized and eat well, children seem to have more organized, better behaviors overall," Dr Benson said.

"So my main message would be that children who are exposed to structure and organization and good food seem to have better adjustment overall, and I would recommend all three of those things, although I suspect that there are some children who consume a Mediterranean diet who still have ADHD," he said.

The study was supported by a grant from the Instituto de Salud Carlos III, Ministerio de Ciencia e Innovacion, Spain. Aleandra Rios-Hernandez was supported by a scholarship from the Consejo Nacional de Ciencia y Tecnologia (CONACYT) of Mexico. The other authors and Dr Benson have disclosed no relevant financial relationships.

Pediatrics. Published online January 30, 2017. Full text


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.