Introduction

More and more people are diagnosed with gastroesophageal reflux disease, or GERD. And being overweight is increasingly common. Could there be a connection? It's been proposed before, but now a study has been done to try to prove a link, and also to see if female sex hormones play a role. Scientists at the Karolynska Institute in Stockholm have examined the data from of two surveys conducted in Norway, and their findings are published in the Journal of American Medical Association.

What was done

Each survey participant completed an extensive questionnaire at a local health center, where they also had a physical exam, and their weight and height measured.

The existence of GERD decided by their answers to questions about heartburn or regurgitation (i.e. reflux) during the previous 12 months. Almost 60,000 people answered the second survey, which was used for this analysis. One in twenty (5%) of the responders had severe symptoms, indicating the presence of GERD.

After pregnant women and those with incomplete answers had been excluded, there were over 3,000 GERD sufferers, who were compared with 40,000 people with no heartburn or regurgitation symptoms, and acted as controls.

The body mass index (BMI) was reckoned as an indication of overweight or frank obesity, and the first survey results were then used to gauge the change in BMI over the previous nine years.

What was found

There were slightly more women than men in the analysis. Those with GERD were 52 years old, on average, compared with the controls, who averaged 48. The average BMI for those with GERD was 28.1, compared with 25.8 for the controls. About 15% of the women with GERD had used hormone therapy, compared with 10% of the controls.

There was a clear link between BMI and reflux symptoms in both men and women. Compared with normal-weight persons (BMI below 25), the likelihood of developing GERD was 3.3 times greater for severely obese men (BMI over 35). Severely obese women were 6.3 times more likely to develop GERD than normal-weight women.

Premenopausal women were at significantly greater risk of GERD than postmenopausal women. In postmenopausal women who were not overweight, those who had used combination hormone replacement therapy were slightly more likely to develop GERD than those who had never used hormones. When estrogen-only replacement therapy was used (i.e. in women who had had a hysterectomy and couldn't use regular combination HRT), there was over twice the likelihood of developing GERD than for women who had never used hormones.

In the 'worst case scenario' of women with a BMI over 35 (severely obese) who had taken estrogen-only hormone replacement, the risk of GERD was 33 times that of normal-weight, non-hormone users.

A weight increase in the 9 years leading up to the main survey was important; an increase of 3.5 BMI units led to a 2.7 times increased risk of GERD. On the other hand, a loss of 3.5 BMI units was linked to a reduction of risk by about 40%.

Comment

This study shows a clear link between GERD and both overweight and, in women, estrogen use. It's known that obese women have an increased production of estrogen-like substances in their fatty tissue, which may explain why weight loss helps reduce the risk of GERD. So, this provides another reason to attack overweight aggressively.