Fruit and vegetable consumption and dietary fat intake were found to play an important role in children's academic performance, highlighting yet again the need for balanced diets at an early age.
Children's nutrition has been permanently in the headlines in recent years, as the effects of an unhealthy diet - primarily obesity and early signs of diabetes - are invreasingly manifested in children around the world.
The contribution of diet to academic performance is nothing new. However, most research so far has focused on the effects of malnutrition and micronutrient deficiency, as well as the effects of breakfast on cognition.
The new study published in the Journal of School Health builds on existing knowledge in the area by identifying specific dietary factors that contribute to the association between children's nutrition and academic performance.
Researchers led by Dr Paul Veugelers of the School of Public Health, University of Alberta, surveyed 5,000 grade 5 students in Nova Scotia, Canada in 2003.
They gathered information on the dietary intake, height, and weight of each student, as well as examining sociodemographic variables.
Using a food frequency questionnaire, the researchers calculated each student's intake of foods from recommended food groups as well as energy and nutrient intakes. On the basis of the latter, they calculated the Diet Quality Index-International (DQI-I), a composite measure of diet quality.
The researches said they opted for the DQI-I because it encompasses adequacy, variety, balance, and moderation as components of diet quality and provides a score for each.
The dietary adequacy component of the DQI-I represents the intake of foods and nutrients essential to a healthy diet such as fruits, vegetables, grains, dietary fiber, protein, iron, calcium, and vitamin C.
Intake of less healthful dietary components such as saturated fat, salt, and 'empty calorie foods' is reflected in the DQI-I moderation score.
The Elementary Literacy Assessment was then used to assess academic performance. This included students to read a variety of materials and answer written questions based on the texts.
The researchers used multilevel regression methods to examine the association between indicators of diet quality and academic performance.
They found that students reporting increased diet quality were significantly less likely to fail the literacy assessment. Relative to students in the lowest DQI-I tertile, students in the second and third tertiles were 26 per cent and 41 per cent less likely to fail.
In particular, Students with an increased fruit and vegetable intake and lower caloric intake of fat were significantly less likely to fail the assessment. Dietary fat intake was also demonstrated as important to academic performance.
"In light of the current childhood overweight epidemic and underlying poor dietary habits, prevention is a public health priority. Our findings suggest enhanced learning as an additional benefit of a healthy diet in childhood," stated the researchers.
"These findings support the broader implementation and investment in effective school nutrition programs that have the potential to improve student's diet quality, academic performance, and, over the long term, their health," they concluded.
Source: 'Diet Quality and Academic Performance'
Journal of School Health, April 2008, Vol. 78, No. 4
Authors: Michelle D. Florence, Mark Asbridge, Paul Veugelers