To prevent further decline of overall dietary quality and help reverse the obesity trend, healthcare professionals need to be aware of the six major threats to healthy diets, and strive to raise parental awareness and education.
A Little Sugar Here, Fewer Nutrients There
Table 1 indicates the association between overall diet quality and the intake levels of selected food groups and nutrients. The proportion of energy from added sugar, for instance, decreases with higher overall diet quality while the proportion of energy from important fatty acids increases. Intakes of all grains, whole grains, vegetables, fruits, and dairy are increasing in preschoolers with better diet quality. However, in the sample used for this study (NHANES 1999-2002), the average intake of whole grains was much below the recommendation of half of the total grains, even in the children with the highest diet quality level (0.6 ounces compared to the recommended 2.8 ounces per day).
Average intake of vegetables and dairy just met the intake recommendation of 2 cups per day while fruit intake was above the recommended 1.5 cups (mean consumption reported = 2.7 cups). The American Academy of Pediatrics recommends that children 1¨C6 years don't consume more than 4¨C6 ounces of 100% fruit juice per day to ensure that children don't ¡°fill up¡± on juice, but rather consume whole fruit and other nutrient-dense foods. In this sample, children in the lowest diet quality quartile consumed more than 4 times that recommended amount (over 24 ounces) and children in the highest quartile consumed approximately one ounce more than recommended (7 ounces). Micronutrient intakes also increased significantly with increasing overall diet quality, and most in the highest diet quality quartile met the age- and gender-specific Estimated Average Recommended (EAR) amounts.
Table 1 not only demonstrates the improvement of dietary intake levels of food groups and nutrients with increasing overall diet quality scores, but also indicates that most children in the U.S. have suboptimal intake levels for almost all of the selected items. By definition, since only one quarter of the population was included in the highest RC-DQI score quartile, we may assume that many American preschoolers have suboptimal intakes of some of the food groups and nutrients needed for adequate growth and good health. For instance, children in the lowest diet quality quartile consumed only about half of the recommended amount of grains, while children in the two lower quartiles did not meet the recommendations for fruits and dairy, and only the preschoolers in the highest quartile met the recommendation for vegetables. Fat intake, on the other hand, was above the recommended intake ranges for preschoolers age 4¨C5 years. Since the total fat recommendation is higher for children under four (30¨C40% of total energy compared to 25¨C35% of energy in older children), most two- and three-year-olds were within the recommended intake range.
Diet Quality Compromised in Six Ways
A diet that promotes optimal growth, development, and prevention of disease in children is considered to be a high-quality diet. It supplies optimal levels of food and nutrients to maintain the body in a healthy state without excess, which may lead to increase in body weight or toxicity symptoms for some nutrients.
Current knowledge and intake recommendations for total energy, food groups, and nutrients are used to estimate diet quality. However, the standards for intake levels considered ideal may vary by recommending agency.6 In the U.S., public health recommendations are typically based on the research conclusions put forth by the Dietary Guidance Advisory Committee. In addition to the type of food in the diet, the amount of foods consumed certainly affects children's health.
Six factors that are reducing diet quality for children include excess consumption of total energy, increased consumption of sweetened beverages, increased fat consumption, low consumption of fiber, decreased diet quality with children's increasing age, and socio-economic factors. Some of these factors are associated or build on one another, such as the increased consumption of added sugar and ethnic background. Others are independent.
Overall diet quality is a complex issue to measure and several different approaches have been published. As a nation, despite the availability of ample and various food choices, we tend to choose a diet that is of low nutritional value. Children are raised on sweet breads, dessert foods, or highly sweetened cereals for breakfast, candy and soda for snacks, and deep-fried dishes for lunch or dinner. As the frequency of eating at home decreases, many children don't experience the former standard of home-cooked meals made from fresh ingredients. These dietary changes not only decrease overall diet quality today, but are likely to track into adulthood and result in low diet quality later in life.
1) Excess Consumption of Total Energy
Analysis of USDA data sets revealed that since 1977, consumption of total energy in U.S. preschool-age children has risen by approximately 150 kcal per day (from 1,389 to 1,557 kcal per day).7 This increase was based mainly on higher consumption of carbohydrates and fat. Simultaneously, the recommended intake levels for several important nutrients and dietary fiber are not met, whereas total and saturated fat as well as added sugar intakes are high.(8) In preschool-age children, the average intake of added sugar increased from 12 to 16 teaspoons per day (1977¨C1998).
At the same time, intakes of fruits and vegetables increased by approximately one-half serving, but consumption levels still fall below the recommended intake level of at least 2.5 cups of fruit or vegetables per day. Total and saturated fat intake in 1998 was too high (33% and 12% respectively, in percent of energy).
In the past three decades, children's consumption patterns shifted from consuming three scheduled meals to having snacks throughout the day.9 Researchers have hypothesized that this eating pattern might be associated with the increase in childhood obesity. Although increased snacking behavior affects total energy intake and body weight in children six years and older, there appears to be no increased energy intake or higher body weight associated with snacking in children ages 3¨C5 years old.10
Children are also consuming more foods away from home than ever before.11 Compared to the 1970s, in 1990 young children ate away from home 50% more often. In 2¨C18 year olds, the energy intake from foods prepared at home decreased from 76% in 1977 to 65% in 1996, while the calories from restaurant or fast-food items tripled, increasing to 15% of total calories. Simultaneously, the proportion of energy from french fries, hamburgers, cheeseburgers, and pizza rose significantly from 4% to 9% of the total energy intake.12 Despite the phenomenon of children consuming more foods, they still lack adequate amounts of fruits, vegetables, and whole grains.13
2) Increased Consumption of Sweetened Beverages
The amount of beverages with added sweeteners¡ªsuch as fruit ades, flavored waters, and regular soda¡ªhas increased in the U.S. food supply. Data indicate consumption of sweetened beverages is on the rise, which has been found to be associated with lower intakes of micronutrients,14 increased consumption of other foods with low nutrient density (such as desserts and salty snacks), and overweight.15
Furthermore, in children 2¨C18 years old, sweetened beverages replace the consumption of milk, a development that decreases children's calcium intake levels.16 For example, in 2¨C5 year olds, consumption of milk decreased from 15% of total energy in 1977 to 10% in 1996, while calories from soft drinks and fruit drinks increased from 5% to 9%. Beverages are a large contributor of added sugar in the diets of preschoolers, and research in nationally representative data sets has indicated that increased added-sugar consumption was associated with lower consumption of a variety of micronutrients and lower overall diet quality.17
3) Increased Consumption of Fat
Overall fat consumption has increased in the U.S.18 ¡ªpossibly a secular trend based on the changes in the food supply. In the recent past, sugars and saturated fat have become the inexpensive food ingredients on the world market; thus, food products tend to have high proportions of these two non-nutritious items.19 In addition, saturated fat is stable and solid at room temperature (won't oxidize or melt easily), thus, it is a very valuable ingredient in food products. Sugar and fat alike add pleasing flavor and texture, a characteristic that increases consumer demand. However, the issue of decreasing the current obesity epidemic by improving the overall diet quality via high-quality commercially products is a point of discussion, and the food industry is developing new products that satisfy economic and health-promoting interests.(20)
The dietary-fat-intake recommendation for young children is higher than for older children and adults (30¨C40% of total energy and 25¨C35%, respectively).21 High-fat intake has been hypothesized to increase the risk for overweight, since fat contributes twice as much energy as carbohydrates or protein (9 kcal/g compared to 4 kcal/g in carbohydrates and protein).22owever, in young children, no association between fat intake and body composition has been found.23 In a study of 77 preschoolers, the amount of body fat was not associated with the amount of carbohydrates, fat, or proteins consumed.24 Of course, body fat is associated with dietary fat intake in adults. To date, there is lack of data on the absolute amounts and food sources of fat consumed by preschool-age children. Since dietary-intake behavior changes with increasing age, understanding the intake regulation of high-fat foods in young children may help prevent excessive energy intake in later childhood and adulthood.
When using dietary-fat intake as an indicator for diet quality, it is pivotal to consider the quality of the fat consumed. Some types of fats, such as omega-3 fatty acids (e.g. linolenic acid), have been found to be beneficial for cardiovascular health.25 Adults consuming at least moderate amounts of this type of fat (e.g., in the form of peanuts), have been found to have better micronutrient intake levels than non-consumers.26 While former dietary intake recommendations focused on the limitation of saturated fat in the diet,27 the recent Dietary Guidelines emphasize the need for the increased consumption of omega-3 and omega-6 fatty acids in the U.S. population.28 High levels of saturated fat consumption concurrent with low intake of poly- and mono-unsaturated fatty acids has been linked to dyslipidemia29
Thus, to improve overall diet quality, the intake of unsaturated fats, such as fats with mono- or polyunsaturated fatty acids, needs to be increased. However, since these fats are not shelf-stable and therefore not easily incorporated into most of the commercially available foods, consumers might need to increase intakes of fatty fish and seed oils in order to meet
4) Decreased Consumption of Fiber
Dietary fibers are naturally occurring non-digestible carbohydrates and lignin in a variety of grains, legumes, fruits, and vegetables. Intake recommendations used to be exclusively based on the naturally occurring fibers in foods, which were measured by standard extraction procedures. The most recent Dietary Guidelines, however, include an additional form of fiber in the American diet: functional fiber. Functional fibers are components of foods that can be isolated or extracted using chemical, enzymatic or aqueous processes¡ªand that are then commonly added to foods.30 The use of total fiber (the sum of dietary fiber and functional fiber) in the dietary intake recommendation was based on scientific evidence indicating that total fiber consumption of 14g/1,000 kcal of energy provides beneficial health effects in adults.31 In many cases, fibers can be both dietary and functional fibers.32
To date, there is no data indicating the quantity of functional fibers actually consumed by children. In adults, the estimated mean consumption is 5 grams per day.33 Assuming that children consume as much functional fiber as adults, the dietary intake recommendation for total fiber should be reduced by 5 grams to 9 g/d in 3-year-olds, 15 g/d in 4¨C8-year-olds, 16 g/d in 9¨C18-year-old girls, 21 g/d in 9¨C13-year-old boys, and 28 g/d in 14¨C18-year-old boys. In the U.S., most children do not meet the intake recommendation for fiber.34 Some may argue that children consume less than 5 g/d because of their lower overall intake of food compared to adults. In either case, preschool-age children are very likely to consume inadequate amounts of dietary fiber, especially in the low-income groups.35
Good sources of dietary fiber in children's diets include whole-grain products and fruits as well as vegetables. Nutrient density might be increased and energy density decreased with higher consumption of fruits and vegetables. These naturally sweet foods contribute large amounts of vitamins and minerals as well as dietary fiber and water, which decreases energy density while increasing satiety.36 Thus, fruit and vegetable intakes help prevent the development of obesity.
Whole-grain products are more energy dense, since whole grains have lower water content than fruits and vegetables. The availability of whole-grain products is continuously increasing in the U.S. food supply. However, recent research has shown that only 8% of the U.S. preschool population met the dietary intake recommendation to consume one half of all grain servings from whole grain.37 Thus, parents and caretakers of young children should be encouraged to replace refined grain products with their whole-grain counterparts, such as whole-grain pasta, breads, and cereals.
5) Older Children Make Unhealthy Choices
Age is an important predictor in the dietary intake patterns of children. Younger kids are more likely to have better diet quality than older ones, even in low-income families, possibly because caretakers not only provide the foods but might also encourage the intake of ¡°healthy¡± foods while allowing ¡°unhealthy¡± foods only as occasional treats.38 One study conducted in Canada showed that young children in very low-income households with single mothers had better diet quality compared to their older siblings.39 Almost 23% of children age 1¨C3 years in single-mother households had good diet quality (measured using the Healthy Eating Index), while only 2% of their 4¨C9-year-old siblings and none of the 9¨C14-year-old siblings were rated as high. This study indicates that mothers might be much more protective of the dietary intakes in young children than in their older offspring.
As children become more independent, their food intake often changes and becomes less healthy due to decreased intake of milk and dairy products but higher intake of salty snacks and sweetened beverages.40 Longitudinal data analysis of 246 children showed that in comparison to dietary intake patterns at age 10 years, young adult's intake (at 19 years) changed significantly for some food groups.41 For instance, while fruit or fruit juice is consumed by 60% of children at age 10, only 31% of the children still consume fruit or fruit juice nine years later. Milk intake decreases from approximately 400 grams per day in younger children to 186 grams per day in the 19-year-olds while sweetened beverages increased from 176 grams per day to a whopping 917 grams per day. Candy intake, on the other hand, decreased from 50 grams per day to 21 grams per day.
One could hypothesize that the increasing independence, peer pressure, food advertisements, socialization, decreasing parental supervision, and other factors influence this change in consumption patterns. However, to date, this area of human nutrition is not fully understood and interactions with physiological and psychological changes during adolescents are very likely. For the practitioner, it is advisable to recognize the importance of children's age on food intake and to help children improve their diet quality by promoting their ability to choose a healthy diet without the assistance of an adult.
6) Socio-Economic Factors
The association between social-economic factors and nutritional status is well established.42 Children from minority backgrounds, for example, are more likely to consume more saturated fat or added sugar than non-Hispanic, White preschoolers. In addition to the cultural influences on dietary intake, low-income families are less likely to have access to health care, but are at higher risk for suboptimal diet quality due to the cost of healthy foods.
A high-quality diet can be expensive. Sweets and salted snacks, for instance, have low nutrition quality but are among the least expensive sources of dietary energy.43 A study on the cost of food and the relationship between family income and obesity indicated that energy-dense, low-quality foods are much more affordable for low-income families than nutrient-dense, high-quality foods.44 On the other hand, food items pivotal for good diet quality¡ªsuch as fruits, vegetables, lean meats and fish, and whole grain cereals or baked goods¡ªare nutrient dense, but more expensive. Thus, family income has a large impact on the likelihood of achieving a high quality diet.45
Federal food programs such as the Food Stamp Program or the Supplemental Program for Women, Infants, and Children (WIC) help low-income families to gain access to high-quality foods. Programs like the Expanded Food & Nutrition Education Program (FNEP) also provide needed nutritional education for low income families. In reality, practitioners need to be aware of parent's financial situation and the number of individuals fed at each meal in order to recommend appropriate dietary changes. One may suggest whole grain cereals with flax seeds and fresh fruit for breakfast rather than a dinner of grilled fish on a bed of fresh vegetables. Using realistic examples of healthy food choices that can fit into the household budget will increase the likelihood of motivating parents to change the foods offered for meals and snacks.
Young children are likely consuming a healthy diet if their parents or caretakers make healthy food choices available to them. Preschoolers appear to have a natural ability to self regulate energy intake; however, this ability decreases quickly with increasing age. Although one study observed this change to take place at four years of age, the exact mechanism and age of change in a larger sample of children remains to be studied.
As children become more independent, they need help to achieve a high-quality diet. Health professionals can emphasize the importance of eating more fresh fruits and vegetables, whole grains, low-fat dairy, and healthy fats while reducing the consumption of added sugar and saturated fat. Overall, parents or caretakers need to be encouraged to improve children's diets one step at a time. Replacing a morning snack consisting of a cookie or candy with fresh fruit or a bowl of high-fiber cereal with milk is adding valuable nutrients to the children's diet. More importantly, it teaches children and parents alike that a healthy diet can be achieved. Another step may be the inclusion of a green or yellow vegetable at every dinner. Granted, children may not be thrilled about this change in the beginning (like most of us, children don't like change), but once it has become part of their routine, eating vegetables with every meal will be a natural behavior that will most likely be maintained for life.
Sibylle Kranz, PhD, is a Registered Dietitian and Assistant Professor in the Department of Nutritional Sciences at Pennsylvania State University. Her doctoral training was completed at the University of North Carolina in Chapel Hill in Nutrition with a minor in Epidemiology. Her research focus is diet quality during childhood and the prevention of childhood obesity.
* Overweight described as Body Mass Index (BMI) z-score 85-94th percentile of CDC growth charts, or BMI z-score 95th percentile. The rate of increase was differentially distributed across ethnic population subgroups¡ªoverweight prevalence increased 73% faster among non-Hispanic Black and 47% faster in Mexican American children than in their non-Hispanic, White counterparts [Ogden CL et al.]. Thus, genetic or cultural influences are putting some children at higher risk.