Medical Edge Newspaper Column

Link Between Soda And Cancer Is Indirect But Real

Aug. 6, 2006
DEAR MAYO CLINIC:
Is there any connection between esophageal cancer and diet soda?

ANSWER:
The quick answer is no: there's no direct connection between esophageal cancer and diet or regular soda. But the quick answer doesn't tell the whole story. There are interconnections between soda, obesity, gastroesophagel reflux disease (GERD) and esophageal cancer that may indicate it's best to go easy on soda.

The incidence of esophageal cancer continues to increase, and so far, researchers can't pinpoint a single reason for the increase. Here are some of the known risk factors:

• GERD: Frequent or constant heartburn is the most common symptom of gastroesophageal reflux disease (GERD). While heartburn seems like just a nuisance, about 5 percent of people with GERD will develop Barrett's esophagus, a condition that occurs when acid reflux stimulates changes in the lining of the lower esophagus. Patients with Barrett's esophagus have a 30- to 125-fold increased risk of developing esophageal cancer. And GERD is also associated with obesity.

• Obesity: While soda alone doesn't cause obesity, it can contribute to weight gain. A 12-ounce regular soda contains about 10 teaspoons of sugar. Diet soda, while calorie free, could contribute to weight gain, too. A study presented at last year's annual meeting of the American Diabetes Association found that for people who drank two or more cans of diet soda a day, the risk of becoming overweight or obese was 57.1 percent, compared to 47.2 percent for those who drank more than two cans of regular soda a day. The study, done by researchers at Texas Health Science Center, tracked 622 people for about seven years.

It's not clear why diet soda consumption was associated with a higher risk of weight gain. The researchers speculated that diet soda drinkers fared worse because they opted for diet soda in an effort to lose weight. But drinking diet soda -- without other changes -- isn't enough to shed pounds. Or, it was theorized that perhaps the artificial sweeteners in diet soda somehow stimulate appetite.

It is clear that maintaining a healthy body weight reduces your risk of many chronic illnesses, including some cancers. While the interplay between soda, obesity and GERD hasn't been directly linked to esophageal cancer, there are enough connections to raise caution and watch what you drink.

-- Claude Deschamps, M.D., Thoracic Surgery; and Jennifer Nelson, R.D., Clinical Dietetics, Mayo Clinic, Rochester, Minn.