Soda, fat, and sin tax
In January, I wrote a blog about the relationship between the consumption of high fructose corn syrup and fat. Almost all sweetened sodas use this type of corn syrup as the sweetener. A story on CNN.com, titled "Scientists in food fight over soda" adds more fuel to the firestorm of controversy about the relationship between sweet soda consumption and obesity. Here are some quotes from the story that outline the evidence supporting a relationship:
"Count One: Guilt by association.
Soft drink consumption rose more than 60 percent among adults and more than doubled in kids from 1977-97. The prevalence of obesity roughly doubled in that time. Scientists say these parallel trends are one criterion for proving cause-and-effect.
Numerous studies link sugary drink consumption with weight gain or obesity. One by Ludwig of 548 Massachusetts schoolchildren found that for each additional sweet drink consumed per day, the odds of obesity increased 60 percent.
Another at Harvard of 51,603 nurses compared two periods, 1991-95 and 1995-99, and found that women whose soda drinking increased had bigger rises in body-mass index than those who drank less or the same.
Count Two: Physical evidence.
Biologically, the calories from sugar-sweetened beverages are fundamentally different in the body than those from food.
The main sweetener in soda -- high-fructose corn syrup -- can increase fats in the blood called triglycerides, which raises the risk of heart problems, diabetes and other health woes.
This sweetener also doesn't spur production of insulin to make the body "process" calories, nor does it spur leptin, a substance that tamps down appetite, as other carbohydrates do, explained Dr. George Bray of the Pennington Biomedical Research Center in Baton Rouge, Louisiana.
"There's a lack of fullness or satiety. The brain just seems to add it on," said Dr. Louis Aronne, a Weill-Cornell Medical College doctor who is president of the Obesity Society.
Two studies by Penn State nutritionist Barbara Rolls illustrate this. One gave 14 men lemonade, diet lemonade, water or no drink and then allowed them to eat as much as they wanted at lunch. Food intake didn't vary, no matter what they drank.
The second study gave 44 women water, diet soda, regular soda, orange juice, milk or no drink before lunch. Total intake was 104 calories greater for those given caloric beverages than those given diet soda, water or no beverage. Caloric drinks didn't help women feel any fuller either.
Then there is the "jelly bean study." Purdue University researchers gave 15 men and women 450 calories a day of either soda or jelly beans for a month, then switched them for the next month and kept track of total consumption. Candy eaters ate less food to compensate for the extra calories. Soda drinkers did not.
Count Three: Bad influence on others.
Sugar-sweetened beverages affect the intake of other foods, such as lowering milk consumption. Popkin contends they also may be psychological triggers of poor eating habits and cravings for fast food.
He examined dietary patterns of 9,500 American adults in a federal study from 1999-2002. Those who drank healthier beverages -- water, low-fat milk, unsweetened coffee or tea -- were more likely to eat vegetables and less likely to eat fast food.
Conversely, "fast-food consumption was doubled if they were high soda consumers and vegetable consumption was halved," he said.
Harvard epidemiologist Eric Rimm saw a similar effect in a different federally funded study of more than 5,000 young adults. With high soda consumption, "you see this pattern of less healthy intake across the board," he said at the obesity meeting.
Count Four: Consistency of evidence.
Many studies of different types link sugary drinks and weight gain or obesity. Some even show a "dose-response" relationship -- as consumption rises, so does weight.
Collectively, they meet many criteria for proving cause and effect, Dr. William Dietz, director of nutrition at the federal Centers for Disease Control and Prevention wrote in an editorial accompanying a study in February's Journal of Pediatrics."
The beverage industry poo-poohs these studies, citing other studies -- by and large industry funded -- that purport to show no or only a weak link between sweetened soda consumption and obesity:
""The science is being stretched," said Adam Drewnowski, director of nutirtional sciences at the University of Washington in Seattle. He owns stock in beverage companies and has done extensive research in the field, much of it financed by industry but also some by government."
Dr. David Ludwig, a Harvard pediatrician and an expert on childhood obesity has proposed a "fat tax" on fast food and sweetened sodas. Others have called for warning labels on soda cans similar to the warnings that appear on cigarette packages and alcoholic beverage containers. Dr. Drewnowski, the pro-soda researcher, thinks "government subsidies of fruits and vegetables would be better public policy than taxing a cheap source of calories."
Regulatory approaches to soda consumption have already begun on the local level with some school districts banning soda machines from school. The Los Angeles Unified School District has even published an organizing guide to help others do the same in their school districts. The Center for Science in the Public Interest is also gearing up for a lawsuit that will seek to ban sales of sugary beverages in schools. It is likely that regulatory and legislative approaches to obesity will continue to be explored.
Overweight and obesity are complex issues that pose serious health threats to adults and children in this country and around the world. Interventions to reduce these threats will need to be multifaceted and should include personal action ("personal responsibility") and as well as broader societal responses, such as regulation and legislation. "Sin taxes" and warning labels may be a part of an overall approach to help people reduce excess calorie consumption.