Fish is brain food, a popular opinion says. Due to its high amount of polyunsaturated fatty acids (PUFA), such as omega-3 and omega-6, which are essential for all mammals, fish consumption is regarded to be advantageous for brain development and function [1, 2]. A possible reason is that phospholipids containing PUFA are integral parts of the neuronal cell membranes of the brain, and they might be important for facilitating the transmission of signals between neurons . Furthermore, micronutrient intake, e.g. iron, magnesium and zinc, has been linked to the development, structure and function of the brain . Consequently, an emerging literature deals with the relationship between nutrition, attention and executive functions in the development of children and adolescents [5, 6].
Evidence indicates that PUFA may play an important role in the prevention and treatment of certain mental health disorders [7, 8] like, for example, attention deficit hyperactivity disorder (ADHD). ADHD is one of the most common behavioural childhood disorders with prevalence rates of 5.29% worldwide  and 4.8% in Germany . Several studies have been conducted, suggesting a link between omega-3/omega-6 fatty acids on the one hand and ADHD symptoms and learning difficulties on the other . Trials with supplementation of a combination of two long-chained omega-3 acids, i.e. eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in children with reading writing disorder (RWD), dyspraxia (i.e., motor coordination difficulties or developmental coordination disorder), and ADHD-related symptoms have reported significant symptom reductions [12–14]. In contrast, trials with DHA only have been less promising [15, 16], suggesting that the presence of the EPA component might be important.
The role of micronutrients has been investigated as well. For example, a study of 48 children  suggests that low zinc levels are correlated with inattentiveness symptoms in children with ADHD. Another randomized, controlled trial of 608 children found that, over a 14-month period, micronutritient supplementation improved attention-concentration symptoms in school children . Nogovitsina and Levitina  identified decreased plasma and erythrocyte magnesium levels and decreases in Mg(2+)-ATPase activity in children with ADHD.
However, the role of specific diets or dietary nutrients in the prevention and management of ADHD is still questioned [20, 21]. A recent review indicates that the evidence is best for zinc . Moreover, a mono-causal role for nutrient deficiencies in children with ADHD or a role for a specific diet in the treatment of ADHD seems to be unlikely. So far, in ADHD guidelines  multimodal treatment is recommended including psycho education, psychosocial interventions, psychotherapy, and pharmacotherapy. Recommendations for dietary nutrients have not yet been implemented. However, many parents follow general nutritional recommendations for the intake of PUFAs and nutrients in order to improve their children's behavioural problems .
Our large observational study focuses on children whose parents judged them to be prone to inattentiveness and hyperactivity and therefore consulted their paediatricians. The paediatricians recommended treatment with ESPRICO®, a chewable capsule which was developed on the basis of current nutritional science containing a combination of omega-3 and omega-6 fatty acids as well as magnesium and zinc, to support attention. The percentage of the EPA in relation to DHA is intentionally high, because studies indicate that especially EPA can effectively improve perception, attention, memory and mood [13, 25–27]. To optimize the benefit for children with attention problems, the food supplement also contains the omega-6 fatty acid gamma-linolenic acid (GLA) and the minerals magnesium and zinc.
By monitoring the children over a period of at least 12 weeks, we evaluated the effects of this dietary measure. In addition, the influence of ESPRICO® on impulsivity, hyperactivity, emotional problems, and sleep related symptoms, as well as the dietary supplement's safety and acceptance were investigated.