Intestinal gases after bariatric surgery may predict less weight loss

SAN DIEGO — After bariatric surgery, patients with gastrointestinal methanogen colonization — assessed by measuring methane and hydrogen in the breath — exhibited less weight loss and BMI reduction than those without detectable colonization, according to research presented here.

“This suggests that gastrointestinal colonization with methanogens might make it harder to lose weight after bariatric surgery,” Ruchi Mathur, MD, of Cedars-Sinai Medical Center, Los Angeles, told Endocrine Today. “Using this noninvasive breath test as a surrogate for identifying the presence of methanogens in the gut may aid in optimizing weight loss in this postsurgical population.”

Ruchi Mathur

Mathur and colleagues at Cedars-Sinai and the Mayo Clinic in Rochester, Minnesota, looked at 156 patients (112 women, 44 men) with obesity who had undergone Roux-en-Y gastric bypass or gastric sleeve surgery.

With data statistically normalized to 6 months, the researchers compared measurements of weight loss and changes in BMI. Patients were asked to perform a single sample breath test, through which intestinal bacterial production of gas — specifically hydrogen and methane — was analyzed

Using parts per million cutoffs for methane and hydrogen of at least 3 ppm and at least 20 ppm, respectively, to define positivity, 13 patients had a lower normalized BMI percentage change compared with all others (20.6 ± 1.9 vs. 23.5 ± 0.6, P = .13) and a significantly lower normalized body weight percentage change (20.05 ± 1.8 vs. 23.9 ± 0.5, P = .036).

Based on the same parts per million cutoff for methane but a more stringent cutoff of at least 10 ppm for hydrogen to define positivity, 18 patients had a lower normalized BMI percentage change compared with all others (20.4 ± 1.6 vs. 23.6 ± 0.6, P = .057) and a significantly lower normalized body weight percentage change (20.1 ± 1.5 vs. 24 ± 0.5, P = .014).

“From a clinical perspective, identification of these particular individuals may allow for interventions in diet and future pharmacotherapy that will enhance their postsurgical course and help them achieve their weight loss goals,” Mathur said. – by Allegra Tiver

Reference:

Mathur R, et al. Abstract PP07-1. Presented at: The Endocrine Society Annual Meeting; March 5-8, 2015, San Diego.

Disclosure: Mathur reports no relevant financial disclosures.