A diet quality index for American preschoolers based on current dietary intake recommendations and an indicator of energy balance

Nutrition Research Newsletter, Nov, 2006

In preschool children, dietary intake is not only linked to growth, development, and nutrition-related disease (such as deficiencies and toxicities), but also to risk factors for chronic diseases, such as obesity, increased cholesterol levels, and hypertension. Because unhealthful lifestyle patterns might continue into adulthood, it is important to strive as early in life as possible for a high-quality diet with optimal levels of food and nutrients to help maintain optimal health. This study was designed to assess the diet quality of a nationally representative sample of American preschoolers based on the dietary intake recommendations released by the National Academy of Sciences (the Dietary Reference Intakes [DRIs] for macronutrients and iron), the new food pyramid "MyPyramid" released by the US Department of Agriculture, and position papers from the American Dietetic Association on diet intake recommendations and American Academy of Pediatrics on the consumption of fruit juice and time spent watching television.

Young children, on average, consume small amounts of food at meals and, therefore, must consume a nutrient-dense diet to provide their bodies with adequate amounts of nutrients for growth and development. They can become nutrient-deficient fairly quickly, especially between the ages of 2 and 5 when they may have low diet variety due to neophobia and periods of poor appetite or food fads. They are at risk for nutrient dilution due to high intake of foods with low nutrient density. Consequently, they can suffer suboptimal health status or even delayed growth and development. Preschoolers' diets are low in fruit and vegetables, even with the inclusion of fried potatoes in the vegetables group. Fruit juices are the main contributors to vitamin intakes.

Currently, there is no adequate measurement tool to assess total diet quality in young children. The purpose of this study was to revise the Children's Diet Quality Index (C-DQI) and develop a new index, RC-DQI (Revised C-DQI) specifically to assess overall diet quality in a nationally representative sample of 2- to 5-year-old American preschoolers. This index is based on current intake recommendations regarding not only nutrients/foods at risk for deficiencies but also items of excessive intake to prevent childhood obesity. A diet quality index for American children between 2 yrs old and 5 yrs old (RC-DQI) was developed based on current intake recommendations. This index is designed to assess diet quality in preschool populations or groups of individuals. Children's total score can be used to rank individuals by their diet quality, or individual components of the RC-DQI can be used to determine adequacy of dietary intake for the specific nutrients and food groups. The index was applied to the dietary intake data of American preschoolers in the CSFII 1994-96 and 1998 data set to determine the diet quality of American preschoolers in a nationally representative data set.

Results indicate that there is room for improvement in children's diets. Even children in the highest RC-DQI quartile still consumed large amounts of added sugar, and consumed too little linoleic and linolenic acid or docosahexaenoic and eicosapentaenoic acid as well as servings of whole grains. Overall, these results are consistent with others in that intake of added sugars, dairy, and fruit juices are excessive, whereas consumption of fruits, vegetables, and whole grains could be increased. Many children did not achieve full points in the dairy component due to overconsumption of milk, a risk factor for low intakes of other foods that might be rich in nutrients. Overconsumption of milk is not assessed in many studies investigating dairy intake in children. Although milk is a favorite food among American preschoolers, milk consumption decreases by the time children reach age 10 and diminishes even more by young adulthood. Thus, studies conducted in older children indicate that dairy consumption is less than the recommended two servings per day. However, due to milk's wide availability and relatively low purchasing price, low-income children are especially at risk for overconsuming milk and dairy products.

The interaction term between the time spent watching television and total energy intake contributes significantly to this index by providing a measure of energy balance. Only children who watched less than one hour of television per day and consumed within 10% of the recommended total energy intake received full credit (10 points) in this component. Children with either higher energy intakes or more time spent watching television received proportionally fewer points, thus indicating that they are not in energy balance. With the exception of the 66 five-year-olds who consumed less than the recommended range of energy intake, children not receiving 10 points in this component were at risk for positive energy balance, and thus at risk for overweight or obesity.

Overall, this index indicates that the current dietary intake recommendations, especially the recommendations for polyunsaturated fatty acid intake as stated in the Dietary Guidelines for Americans 2005, are likely to be met only by children consuming large amounts of foods. This is due to the lack of diet variety among preschoolers and the low consumption of fatty fish in this age group. However, although the recommendations used in the RC-DQI were met only by a small proportion of children, those individuals are likely to meet or exceed the recommendations for micronutrients and the adequate intakes for calcium. Increased nutrient density, especially for polyunsaturated fatty acids and fiber, could greatly improve children's dietary quality without increasing the risk for childhood obesity. Compared with the original C-DQI, this revised diet quality index allows higher total fat intakes and includes more components related to the quality of fat consumed rather than the limitation of saturated fat amounts in the diet. The intakes of the food group recommendations have increased to reflect MyPyramid, and whole grain was added as an individual component. To address the issue of positive energy balance, the interaction between time spent watching television and total energy consumed was incorporated. The results of this study show that the average American preschooler is at higher risk for overconsumption of high-energy, low-nutrient foods rather than for deficient intakes in some of the main food groups. Although fat consumption should not be emphasized in young children, it contributes to energy density of foods, a risk factor for excessive energy intakes in a population for which nutrient density is crucial for healthy growth and development.