Hamburgers and french fries typically take the rap as the worst villains in the U.S. diet. But people in this country may in fact be drinking, rather than eating, their main sources of calories, reports Odilia Bermudez of Tufts University in a new study.
"When you put together soda and fruit drinks, that seems to be in first place as energy provider in the American diet," says Bermudez, who presented the preliminary results of her ongoing study at the Experimental Biology conference in April. "This is something to worry about."
Using data from the National Health and Nutrition Examination Survey 1999–2000, Bermudez looked at the diets of 961 black, Hispanic, and white adults ages 20 to 49. She discovered that two-thirds of these adults drank an average of 2.6 cups of sweetened beverages a day.
She then calculated the total energy contribution of these soft drinks, which include sodas and drinks containing less than 10 percent fruit juice, to the diets of the people who drank them. The drinks represented 14 percent of these adults' total daily energy intake. "For the nutrition world, that's an extremely high value," Bermudez says.
She explains that, 10 years ago, white bread was the mainstay of the U.S. diet—at an energy contribution of only 5 to 7 percent. Before the 1990s, sodas and fruit drinks provided only about 5 percent of the average person's daily calorie load, she adds.
Fizz and fat
Bermudez' new study links the sweet beverages to obesity. People who consumed the drinks had a higher body mass index (BMI), the usual measure of obesity, than those who drank only low-fat milk and 100-percent orange juice. Bermudez asserts that soft drinks are one factor contributing to a widely documented "obesity epidemic" in the United States.
Data from the Centers for Disease Control and Prevention show that U.S. obesity rates have climbed from about 15 percent in 1975 to more than 30 percent in 2002, says David Levitsky of Cornell University. This epidemic has troubled nutritionists because of obesity's correlation to heart disease, diabetes, stroke, and other ailments, he adds.
Dieters may not realize how sugary beverages affect them, because they focus on avoiding calorie-rich solid foods, says Robert Murray of Ohio State University. "Liquid calories like this, I think we tend to just ignore them," he says.
Although Bermudez' findings might startle consumers, Murray says he's "not overly surprised" by the new data. In the May Journal of Pediatrics, he and his colleagues reviewed existing studies on the impact of soft drinks on children's diets and obesity levels. The researchers found that U.S. children and teenagers consume, on average, about two cans of soda or fruit drink a day. And a quarter of all teens drink as many as four cans a day, each one containing about 150 calories.
"That's a lot of calories. That's 600 calories," Murray says. "That's like an additional meal." For a teenage girl, who should be eating around 1,800 calories a day, he adds, "that's a third of her daily energy requirement taken in the form of just one food, soft drinks."
A host of problems accompanies such excessive sweet-beverage consumption, Murray's team found. The more sodas and fruit drinks children drank, the more obese they tended to be. Soft drinks also displaced milk in children's diets, diminishing their intake of nutrients such as calcium, iron, folic acid, and zinc.
The same holds true for adults, Bermudez points out. In 1945, U.S. adults drank four times as many gallons of milk as of carbonated beverages, according to data from the U.S. Department of Agriculture. By 1997, they drank two and half times as much soda and sweetened juice as they did milk. Since 1970, milk consumption per person has declined 23 percent in the United States.
The sweet life
In a tendency that contributes to obesity, people usually add liquid calories to their regular meals, rather than eating less to counterbalance the additional calories, Murray notes. This nutritional habit, usually learned in childhood, tends to dog consumers into their adult years, he says.
Even small increases in calorie intake over an extended period of time could be responsible for rising obesity rates, Levitsky says. He has calculated that a mere 7 to 10 additional calories per day over 30 years would suffice to produce the observed increase in average weight among U.S. citizens. Since soft drinks typically contain 100 to 150 calories per can, "that's taking a[n extra] soda once a week," he says.
Murray notes, however, that eliminating soft drinks wouldn't end the United States' obesity epidemic. Genetics, low activity levels, high intakes of snack foods, and other factors also play important roles.
"But most dieticians are pretty creeped out" by new data on the typical intake of sweetened drinks, Murray says. "I can't think of too many of them who think there's a good side to that level of consumption. It's just too much."
People in the United States should consider limiting children's access to sweetened drinks, particularly in schools, Murray suggests. His recent review of children's diets indicates that 50 percent of school districts had a contract with a soft drink company in 2000. Two-thirds of these districts received part of the proceeds from soft drink sales in schools, and a third allowed advertising of the beverages in school buildings.
Bermudez says that both children and adults need to become aware of their level of soft drink consumption and consider drinking other beverages instead. "We should be looking for ways to increase the quality of our diet. Plain water or 100-percent juices, they are healthier choices," she says.
Dietary Assessment and Epidemiology Research Program
Jean Mayer USDA HNRCA at Tufts University
711 Washington Street
Boston, MA 02111-1524
Division of Nutritional Sciences
Ithaca, NY 14853
Borden Center for Nutrition and Wellness
Ohio State University
Division of Gastroenterology and Nutrition
Columbus Children's Hospital
700 Children's Drive
Columbus, OH 43205
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