Studies more firmly tie sugary drinks to obesity
By MARILYNN MARCHIONE AP Chief Medical Writer September 24, 2012 3:10PM
Studies show that soft drinks containing sugar may trigger genes that cause obesity.
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Updated: October 27, 2012 6:06AM
New research powerfully strengthens the case against soda and other sugary drinks as culprits in the obesity epidemic.
A huge, decades-long study involving more than 33,000 Americans has yielded the first clear proof that drinking sugary beverages interacts with genes that affect weight, amplifying a person’s risk of obesity beyond what it would be from heredity alone.
This means that such drinks are especially harmful to people with genes that predispose them to weight gain. And most of us have at least some of these genes.
In addition, two other major experiments have found that giving children and teens calorie-free alternatives to the sugary drinks they usually consume leads to less weight gain.
Collectively, the results strongly suggest that sugary drinks cause people to pack on the pounds, independent of other unhealthy behavior such as overeating and getting too little exercise, scientists say.
That adds weight to the push for soft-drink taxes, portion limits like the one just adopted in New York City, and other policies to curb consumption.
The studies were being presented Friday at an obesity conference in San Antonio and were published online by the New England Journal of Medicine.
The gene research in particular fills a major gap in what we know about obesity. It was a huge undertaking, involving three long-running studies that separately and collectively reached the same conclusions. It shows how behavior combines with heredity to affect how fat we become.
Having many of these genes does not guarantee people will become obese, but if they drink a lot of sugary beverages, “they fulfill that fate,” said an expert with no role in the research, Jules Hirsch of Rockefeller University in New York. “The sweet drinking and the fatness are going together, and it’s more evident in the genetic predisposition people.”
Until now, high-quality experiments have not conclusively shown that reducing sugary beverages would lower weight or body fat, said David Allison, a biostatistician who has done beverage research at the University of Alabama at Birmingham, some of it with industry support.
He said the new studies on children changed his mind and convinced him that limiting sweet drinks can make a difference.
In one study, researchers randomly assigned 224 overweight or obese high schoolers in the Boston area to receive shipments every two weeks of either the sugary drinks they usually consumed or sugar-free alternatives, including bottled water.
After one year, the sugar-free group weighed more than 4 pounds less on average than those who kept drinking sugary beverages.
A second study involved 641 normal-weight children ages 4 to 12 in the Netherlands who regularly drank sugar-sweetened beverages. They were randomly assigned to get either a sugary drink or a sugar-freeone.
After 18 months, the sugary-drink group weighed 2 pounds more on average than the other group.
The studies “provide strong impetus” for policies urged by the Institute of Medicine, the American Heart Association and others to limit sugary drink consumption, Dr. Sonia Caprino of the Yale School of Medicine wrote in an editorial in the journal.
The genetic research was part of a much larger set of health studies that have gone on for decades across the U.S., led by the Harvard School of Public Health.