Prevalence of obesity and cardio-metabolic disease are increasing rapidly worldwide. Although energy imbalance is generally considered the driver of this increase, changes towards more unhealthy dietary behaviours are likely to contribute additionally. These dietary behaviours are therefore worth evaluating and tracking in populations. However, the complexity of diet means that evaluating individual dietary behaviours provides limited information, yet measures that provide a more comprehensive picture are sparse.

Dietary Energy Density (DED), the amount of calories per weight of the diet, is positively associated with obesity and the metabolic syndrome¹. Higher DED is also associated with lower dietary quality^2,3, including lower fruit and vegetable intake, and an overall less-healthy lifestyle pattern⁴. Furthermore, DED has been suggested for use as a proxy of the nutritional quality of the diet^5,6. DED estimates may therefore be used as an indicator of overall dietary behaviours. These estimates provide a tool to track secular trends in diets and to examine dietary trends by population traits, for example age groups. Distinguishing dietary components that determine DED in free-living populations may be useful in explaining differences in DED estimates over time and tailoring public health guidelines aimed at improving diets.

A study of DED estimates, trends and dietary determinants:

Using data from a suite of national food consumption surveys in Ireland (www.iuna.net), DED estimates were calculated for 2,395 boys, girls, men and women, aged 5-90 years. For each survey, food intake data were assessed by way of detailed food records with careful attention to the estimation of portion weights.

Higher mean DED estimates were associated with a higher intake of energy. Higher DED was also associated with a greater proportion of energy from fat, carbohydrate and sugars and, a lower proportion of energy from protein and dietary fibre. With regard to food intakes, higher DED was associated with higher intakes of white bread, ready-to-eat breakfast cereals, processed meat, chips, savoury snacks, chocolate, sweets, sugar-sweetened beverages and alcoholic beverages and lower intakes of vegetables, fruit, soup, potatoes, fresh meat, brown bread, fish, egg, pulses, cooked breakfast cereals (e.g. porridge) and nuts. DED estimates were inversely associated with age group and were consistently higher for men than women. Variation in the intakes of fruit, vegetables and sugar-sweetened beverages contributed to the largest variance in DED estimates and explained much of the difference in DED estimates by age group and between men and women. Further findings from the study revealed that DED estimates were remarkably similar in two comparable surveys of Irish adults (18-64y) carried out 10 years apart.

Public health and policy implications:

The intakes of fruit, vegetables and sugar-sweetened beverages appear to have the greatest influence on DED in the Irish population and are potential targets for public health interventions.

In the Irish population, DED estimates trended inversely with age and were lower in women than in men. Estimates did not change appreciably in 10 years, suggesting an absence of a generational effect and supporting the observation of a trend with age. The age and sex stratified estimates from this study can serve as a baseline for comparison for other works and for public health campaigns.

This study was supported by the Irish Government under the National Development Plan (2000–6) and the Department of Agriculture, Fisheries & Food under the Food for Health Research Initiative (2007–12).

Based on: L. O’Connor, J. Walton and A. Flynn (2015) Dietary energy density: estimates, trends and dietary determinants for a nationally representative sample of
the Irish population (aged 5–90 years) British Journal of Nutrition. 113: 172–18.