School vending machine use and fast-food restaurant use are associated with sugar-sweetened beverage intake in youth

Nutrition Research Newsletter, Nov, 2006

Sugar-sweetened beverages include nondiet sodas, iced teas, fruit drinks, and sport drinks that provide most or all of their calories from refined carbohydrate and have little or no inherent nutritional value. A 12-oz can of soda can contain nine or 10 teaspoons of sugar, while the same amount of fruit drink can contain 12 teaspoons. Sugar-sweetened beverages can have unintended health consequences antagonistic to halting the epidemic of overweight among American children and youth. Among youth, soft drink consumption has been associated with higher energy intakes and with lower intake of milk or calcium, 100% fruit juice, and micronutrients. Soft drinks contribute more energy to the diets of overweight youth than to those of nonoverweight youth. Prospective studies among youth have indicated that increased sugar-sweetened beverage intake is positively associated with both increased BMI, and obesity incidence. Efforts to reduce total energy intake by focusing on nonnutritive calories need to reflect the fact that no foods contribute as much added sugar to our diets as nondiet sodas and sweetened fruit drinks. The refined carbohydrate they contain is "added sugar," that is, sugar added during manufacturing. Consumption of added sugars peaks in the adolescent and teen years at about 20% of daily calories, whereas experts recommend no more than 6% to 10%. Among 12- to 17-year-olds, nondiet soda provides 40% of all calories from added sugar, while sweetened fruit drinks contribute an additional 11% to 13%.

From an intervention standpoint, where youth obtain sugar-sweetened beverages is a critical data point. School vending machines typically offer a wide array of sweetened beverages in addition to soft drinks (as well as other food items), and are not the only source of such drinks in schools. In a recent study, CDC officials noted that in 27 states 79% to 100% of secondary schools surveyed sold sugar-sweetened beverages in vending machines or other school venues. Studies show that roughly half of middle schools have contracts with vendors to sell soft drinks, and that 87% of junior high and middle schools have vending machines where children can buy foods or drinks. Given the broad reach of schools, the possible deleterious effects of sugar-sweetened beverages on health, and the ubiquity of sugar-sweetened beverages in schools, it is prudent to look to schools as a practical locale for reducing added sugar intake.

Fast-food restaurant use is also on the rise and contributes to increasing sugar-sweetened beverage consumption among youth. Fast-food restaurants now supply about 22% of soft drinks consumed by youth. Such restaurants are positively associated with energy intake in youth and, in a recent study, children who ate fast food on a given day, compared to those who did not, consumed more calories, fat, added sugars, and sugar-sweetened beverages, and fewer servings of milk, fruits, and nonstarchy vegetables. While fast-food meals accounted for 3% of eating occasions and 3% of daily calorie intake in 1977, in 1995 they accounted for 9% of eating occasions and 12% of calories. In this study, the researchers examine whether students' use of school vending machines and fast-food restaurants are independently associated with children's consumption of sugar-sweetened beverages.

In the 2002/2003 and 2003/2004 school years, 13 Massachusetts middle schools participated in 5-2-1-Go!, a group randomized trial of an intervention to reduce obesity conducted by the Massachusetts Department of Public Health. Schools invited to participate in the study were the 289, serving grades 6 to 8, that were participants in the Massachusetts Department of Public Health Enhanced School Health Services program. Of these, 16 agreed to participate and to be randomized into an intervention or control group; three subsequently dropped out after randomization and before implementation, and another three were later eliminated from this analysis. The 10 remaining study schools were located in 10 communities with a broad range of demographic characteristics.

The number of vending machines at each school ranged from one to five, for a total of 20. All of the 10 schools sold soda and/or other sweetened drinks in their vending machines. Two sold regular (sweetened) soda, seven sold other sweetened drinks, and one sold both categories of beverages. Other items observed in vending machines and the number of schools where they were sold were: water (four schools), 100% fruit juice (two schools), salty snacks (one school), cookies (one school), and ice cream (two schools). The researchers were able to ascertain student access to vending machines from staff at eight of the schools; of these, three schools reported no access restrictions on any of their machines; one school had one machine restricted to access only at lunch, and two with no restrictions; three schools reported access only at lunch; and one school did not provide specifics.

There were 646 students (43%) who reported purchasing at least one item from school vending machines in the seven days preceding the survey, among whom the category most frequently reported for purchase was "sweetened drinks other than soda (like Fruitopia, iced tea, or sport drinks)" (n=413 students; 64%). Nondiet soda was purchased by 69 students (11%). In total, 456 students (71%) reported purchasing sugar-sweetened beverage (either a sweetened drink or a nondiet soda), including 68% of 505 students that bought one to three school vending machine items, but 79% of 141 who bought four or more. After sweetened beverages other than soda, the next most frequently reported item was water (140 students, 22%), followed by ice cream (125; 19%). With respect to fast-food restaurant use, 977 students (66%) reported eating at one at least once in the past seven days (not shown).