Americans drink more than 13 billion gallons of soda each year, and many of them stick loyally to diet formulas. But studies have shown that reaching for the silver Coke can instead of the red one may not be as effective in the battle of the bulge as many diet soda drinkers think, as artificial sweeteners may carry other health risks or induce people to overeat.
The average American consumes 150 pounds of sugar each year, and much of it comes from drinking 900 cans of soda a year, according to a study by the Center for Science in the Public Interest. The study also found that soda is the largest source of refined sugar in the average American diet and accounts for 7 percent of a person’s caloric intake.
Diana Garza Ciarlante, a spokeswoman for Coca-Cola North America, said in an email that Coca-Cola’s diet carbonated sodas and non-carbonated beverages, which are sweetened with aspartame, account for roughly 45 percent of unit sales in the United States.
“Aspartame is a safe, officially approved and widely used intense sweetener, in a wide variety of food and drink products,” she said. “It is one of the most scientifically tested sweeteners in the world. Its use is driven by consumer taste preferences.”
But according to “A Pavlovian Approach to the Problem of Obesity,” a study conducted by Purdue University’s Professor Terry Davidson and Associate Professor Susan Swithers, diet sodas can interfere with the body’s natural ability to count calories.
Davidson told the Purdue News that artificial sweeteners can weaken the body’s natural ability to regulate food intake and body weight.
“Our hypothesis is that experience with these foods interferes with the natural ability of the body to use sweet taste and viscosity to gauge caloric content of foods and beverages,” Swithers said, according to the same Purdue News article. “When you substitute artificial sweetener for real sugar, however, the body learns it can no longer use its sense of taste to gauge calories. So, the body may be fooled into thinking a product sweetened with sugar has no calories and, therefore, people overeat.”
Aspartame, or NutraSweet, is the sugar substitute most commonly used in diet sodas. Although it is also the most tested sweetener, according to the U.S. Food and Drug Administration, it carries serious risks for people who have Phenylketonuria, a genetic disorder that prohibits proper deconstruction of phenylalanine, one of the two amino acids that comprise the sweetener.
Because PKU is impossible to detect before birth, pregnant women should not consume any products containing aspartame, according to Dr. Joseph Mercola, who operates a health and fitness website, www.mercola.com, and is author of the book Total Health Program. The common misconception that people without the disorder are still susceptible to its risks, which include mental retardation from buildup of phenylalanine in the brain, has turned many people away from beverages that use aspartame, Mercola says.
But Ciarlante said concerns over aspartame are misplaced.
“Aspartame is used in more than 6,000 products around the world and has been in use for more than 20 years,” Ciarlante said. “Claims about its lack of safety have been part of Internet/urban legend lore for many years, but after thorough investigations no claims of harm have ever been substantiated.
“More than 200 studies have been conducted on aspartame with more than 100 of these conducted prior to aspartame’s approval,” she continued. “The studies have evaluated a wide variety of populations…. In addition, claims by individuals who were convinced that aspartame caused their headaches, seizures or allergies were evaluated. The results of these studies demonstrated that aspartame is not associated with adverse health effects.”
Tracy Halliday, spokewoman for the American Beverage Association, agreed that diet sodas are safe.
“As recently as this year, the National Cancer Institute, in a study of over a half million people who drank diet or low-calorie beverages determined that there was no increased risk of cancer — even among those who drank three or more diet soft drinks a day for years,” she said in an email.
Aspartame’s popularity can be attributed to timing. Saccharin, commonly known as Sweet ‘n Low, was the most popular artificial sweetener until the FDA proposed a ban in 1977 to study claims that it could cause cancer. In response to public outcry, Congress enacted a moratorium that prohibited the FDA from enacting a ban, but required distributors of saccharin products to print a label on each packet, warning that the sweetener may be carcinogenic.
In 1991, when researchers discovered that evidence from testing was not sufficient to link to tumors in humans as it had shown in test rats, the FDA lifted its ban proposal, according to the Calorie Control Council. In 2000, President Bill Clinton signed a bill that removed warning labels from saccharin-sweetened products. But by that time, aspartame had emerged as the leading sugar-free sweetener.
The FDA has approved five artificial sweeteners. They include Acesulfame Potassium, or Sunette, which is 200 times as sweet as sugar and was approved in 1988; Sucralose, or Splenda, which is 600 times as sweet and was also approved in 1988; Neotame, a derivative of aspartame, which was approved in 2002 and is 8,000 times as sweet as sugar, and aspartame and saccharin, which were approved in 1981 and 1879 and are 200 and 500 times as sweet as sugar, respectively.
“Sugar substitutes allow consumers to enjoy certain foods or beverages while consuming little or no extra calories,” Halliday said, so they help control calorie intake.
“We do know, however, that the key to maintaining a healthy weight is through a balanced lifestyle. That includes regular exercise and the consumption of a variety of foods and beverages in moderation,” she continued.
Joan Salge Blake, clinical assistant professor and dietetic internship director at Boston University’s Sargent College of Health and Rehabilitation Sciences, said diet sodas can help soda drinkers control sugar, but are not the “magic bullet by any stretch of the imagination.
“We’ve been having diet soda forever,” Blake said. “Look what’s happening — weight is still going up.”
Blake, who writes a nutrition column on the Oxygen Network’s website and is a member of the ABC News Medical Expert Network, said it takes a lot more than simply switching from regular to diet soda to stay fit.
“The whole purpose of sugar substitutes is to decrease calories and give a sweet sensation,” she said. “Americans are having a battle with weight and are losing. [Diet soda] doesn’t seem to be halting the obesity epidemic.
“We don’t want to consume empty calories,” she continued. “We’re eating too many refined carbohydrates, and just because something is labeled as sugar-free does not mean it’s also calorie-free. We need to return to the basics and eat a healthy diet — fruits and vegetables will fill you up before they fill you out. We don’t want to be filling up on Diet Coke all day.”