MONDAY, May 10, 2005 (HealthDay News) -- The nearly one in two American adults plagued by heartburn may want to steer clear of carbonated soft drinks in the hours before bedtime, with a new study linking soda consumption to troublesome acid reflux at night.
"That's no small matter, because acid reflux during the night tends to be more harmful for patients -- it's associated more with complications, such as narrowing of the esophagus, alterations of the esophagus and, most importantly, cancerous changes of the esophagus and esophageal cancer. That's a big price to pay for a can of Coke," said lead researcher Dr. Ronnie Fass, a professor of medicine at the University of Arizona, Tucson.
His team's study, published in the May issue of Chest, also found strong associations between troubling nighttime heartburn and the use of benzodiazepine sleeping aids such as Ativan, Valium or Xanax.
According to experts, approximately 44 percent of adult Americans complain of heartburn at least once a month, while 14 percent -- nearly one out of six -- experience weekly bouts of heartburn. Fass described heartburn as "a burning sensation people usually feel after meals, behind the chest bone and rising up to their throat, caused by acid reflux."
In the study, Fass' team examined data from the large, ongoing Sleep Heart Health Study, aimed at investigating connections between disturbed sleep and cardiovascular health.
Of the more than 15,000 adults surveyed in that study, more than 3,800 (24.9 percent) complained of heartburn during nighttime slumber.
The researchers pored over the collected data to determine dietary and lifestyle factors associated with nighttime reflux.
"For the first time, we found a close relationship between soft drink consumption and this type of severe heartburn," said Fass. Individuals who drank one or more servings of carbonated soft drinks per day were at 31 percent higher risk of developing heartburn at night compared to individuals who stayed away from these types of beverages.
"We think there are two reasons for that," said Fass, who is also director of the Southern Arizona VA HealthCare System's Gastrointestinal Motility Laboratories. "First, a lot of carbonated beverages are very acidic. The other thing is that they deliver a lot of air -- in the form of carbon dioxide -- which can cause distension of the stomach. And that distension appears to be associated with more reflux."
Regular use of benzodiazepine sedatives -- popular prescription sleep aids which include Ativan, Halcion, Valium and Xanax -- was also associated with a 65 percent increased risk of heartburn after bedtime, the researchers found.
"We know from physiological studies that benzodiazepines weaken the barrier between the esophagus and the stomach, allowing acid reflux to occur," Fass said. He advised that patients who take these drugs and experience nighttime heartburn discuss the issue with their doctor, since "there are non-benzo sleeping pills available."
Fass stressed that nighttime heartburn is more than just a nuisance. Besides keeping individuals up at night and making them drowsy the next day, nighttime reflux "may be indicative that a person has a more severe form of the disease," Fass said. He pointed out that, during the daytime, simple acts such as swallowing (which dilutes reflux acid) and taking antacids can help minimize heartburn symptoms.
"But when you go to sleep, sleep-time physiology applies," he said. "You'll have acid reflux but not swallow -- so the acid is staying there longer in the esophagus, causing more damage."
Besides switching sleep medicines, Fass recommends avoiding sodas late in the day. "If you want to drink a carbonated beverage, don't drink it in the evening, or with dinner," he advised. Besides their immediate effects on the stomach, heavy consumption of high-calorie sodas can lead to obesity over time, he noted, "and we are also seeing a close relationship between overweight and these types of [heartburn] symptoms."
Dr. Stuart Spechler, chief of gastroenterology at the Dallas VA Medical Center, and a spokesman for the American Gastroenterological Association, called Fass' theory that sodas raise reflux risk by distending the stomach a "plausible hypothesis."
But he added that any food introduced into the stomach before bedtime might be problematic.
"If you are predisposed to having heartburn, I think that having anything at night just before you go to bed might increase risk," he said. "You're stimulating the stomach to make more acid by eating, and if you do that just before bed it's going to be making more acid at night while you're sleeping."
For more on the causes and treatment of heartburn, head to the American Gastroenterological Association.