Child Cognition: Does Overall Diet Quality Matter?

As physical education in schools has continually declined, children have fewer opportunities for physical activity. That combined with greater access to nutritionally poor yet calorically dense foods has contributed to a problem many of us are familiar with -- healthy behaviors may not be supported by environmental factors. As health and wellness professionals, we know the impact poor nutrition can have on childhood obesity and chronic disease risk. But what about the role of diet quality on child cognition? 

While the specific effects of particular nutrients or foods on cognitive function are still not clear, the emerging literature suggests that an overall greater diet quality may have the potential to contribute to both physical and mental health among today’s youth.

First, it’s important to recognize that nutrients play vital roles in the brain as energy sources, structural components, precursors to neurotransmitters and the brain’s immune system. In addition, throughout childhood and adolescence the brain undergoes extensive developmental changes. Therefore, childhood provides an important window of opportunity to examine the role diet may play in supporting both physical and cognitive development.

Research studies in animal models and some human trials show deficiencies in key nutrients (e.g., omega-3 fatty acids, iodine, zinc, choline, B vitamins and iron) can directly lead to diminished brain structure and function (Rytych 2012, Georgieff 2007, Prado 2014). Severe malnutrition in the first few years of life may be associated with decreased cognitive function, intelligence and behavior problems in later childhood, especially if the environment is not improved later on.

However, if a child is not deficient of nutrients, does a greater diet quality benefit his or her cognitive function? In an earlier observational study, we reported that healthy elementary school-aged children who ate more saturated fatty acids (SFA) showed impairments in memory compared to children who consumed less SFAs, while children who ate foods rich in omega-3 fatty acids showed greater memory or recollection for the associations between multiple items. However, a limitation of focusing on single nutrients (such as dietary fatty acids in this case) is that this approach fails to account for overall diet quality.

Our study associated preadolescent children who consumed a higher quality diet (as measured by the Healthy Eating Index) with the ability to avoid distractions and focus on relevant information – this was particularly true for higher fiber consumption. Other researchers have found a positive association of overall diet quality with academic performance among fifth grade children. These diet quality indices emphasize the importance of eating foods most American children fail to meet the recommendations for, including dark green leafy vegetables, whole grains and dairy foods.

Although the relationship between diet quality and child cognition is an emerging area of research, the current knowledge is largely derived from correlational studies, thereby limiting our understanding of the causal links between diet and cognition. Further, it is difficult to apply the current cognition literature to the greater public due to the emphasis on specific populations (i.e. extremely malnourished) and use of varying diet and cognition assessment techniques.

Although habitual diet quality appears to be associated with greater cognitive function in children, additional randomized-controlled trials are needed to determine the impact of eating patterns on children’s cognitive function.