Extra pounds, smoking confirmed GERD risks

NEW YORK (Reuters Health) - A new study in identical twins confirms that excess weight and cigarette smoking increase the risk of gastroesophageal reflux disease (GERD).

While strenuous physical activity on the job also increases GERD risk, leisure-time exercise decreases the risk, Dr. Zongli Zheng and colleagues from the Karolinska Institutet in Stockholm, report in the medical journal Gastroenterology.

A number of previous studies have tied these factors to GERD, but the current investigation is the first to include identical twins. Because identical twins have exactly the same genetic make-up, this allowed the researchers to separate the effects of genetics from environmental factors.

Zheng and colleagues evaluated 27,717 men and women, including 869 sets of identical twins. In each twin pair, one twin had GERD, while the other did not.

In 1967 and 1973, the study participants completed questionnaires on lifestyle habits, such as exercise and diet, and then reported on GERD symptoms in telephone interviews conducted between 1998 and 2002.

GERD risk increased with body mass index. Compared with women with a normal body mass index, those in the upper-normal, overweight, and obese categories had an increased GERD risk of 25 percent, 46 percent, and 59 percent, respectively. For women who were lean, the risk of GERD decreased by 19 percent.

Genetic factors played a greater role in the GERD-obesity link among men than women. This may be because, the researchers note, obesity appears to have a stronger genetic link in males than females. The GERD risk for men for the upper-normal, overweight and obese categories were 44 percent, 187 percent, and 277 percent, respectively, with a 28 percent decrease in risk among the lean men.

In both men and women, smoking increased GERD risk, and the more people smoked, the greater their risk.

However, the researchers found no link between alcohol consumption and GERD. Furthermore, heavy coffee drinking appeared to actually protect men from GERD. This may be because people who are heavy coffee drinkers are less likely to gain weight over time, they suggest.

The strenuous work-GERD link could have been due to these workers having to exert themselves after meals, which can promote reflux, the researchers note, while people exercising at leisure are less likely to do so with a full stomach.

SOURCE: Gastroenterology, January 2007.