"Methanogens are a type of microorganism that produces methane as a byproduct of metabolismin conditions of very low oxygen. They are often present in bogs, swamps, and other wetlands, where the methane they produce is known as "marsh gas." Methanogens also exist in the guts of some animals, including cows and humans, where they contribute to the methane content of flatulence. Though they were once classified as Archaebacteria, methanogens are now classified as Archaea, distinct from Bacteria.
Some types of methanogen, including those of the Methanopyrus genus, are extremophiles, organisms that thrive in conditions most living things could not survive in, such as hot springs, hydrothermal vents, hot desert soil, and deep subterranean environments. Others, such as those of the Methanocaldococcus genus, are mesophiles, meaning they thrive best in moderate temperatures. Methanobrevibacter smithii is the prominent methanogen in the human gut, where it helps digest polysaccharides, or complex sugars."
The benefits of weight loss surgery, along with a treatment plan that includes exercise and dietary changes, are well documented. In addition to a significant decrease in body mass, many patients find their risk factors for heart disease are drastically lowered and blood sugar regulation is improved for those with Type 2 diabetes.
Some patients, however, do not experience the optimal weight loss from bariatric surgery. The presence of a specific methane gas-producing organism in the gastrointestinal tract may account for a decrease in optimal weight loss, according to new research by Ruchi Mathur, MD, director of the Diabetes Outpatient Treatment and Education Center at Cedars-Sinai.
"We looked at 156 obese adults who either had Roux-en-Y bypass surgery or received a gastric sleeve. Four months after surgery we gave them a breath test, which provides a way of measuring gases produced by microbes in the gut," said Mathur. "We found that those whose breath test revealed higher concentrations of both methane and hydrogen were the ones who had the lowest percentage of weight loss and lowest reduction in BMI (body mass index) when compared to others in the study."
The methane-producing microorganism methanobrevibacter smithii is the biggest maker of methane in the gut, says Mathur, and may be the culprit thwarting significant weight loss in bariatric patient. Mathur and her colleagues are conducting further studies to explore the role this organism plays in human metabolism.
While that research continues, bariatric patients may still have options to improve weight loss after surgery.
"Identifying individuals with this pattern of intestinal gas production may allow for interventions through diet. In the future there may be therapeutic drugs that can improve a patient's post-surgical course and help them achieve optimal weight loss," said Mathur.
The study, "Intestinal Methane Production is Associated with Decreased Weight Loss Following Bariatric Surgery" was done in collaboration with the Mayo Clinic. The paper is being presented by Mathur Thursday, March 5, at the 97th annual meeting of the Endocrine Society in San Diego.