Breath Study Shows Link Between Obesity And Microorganisms Living In The Gut

We've all smelled bad breath. But what about fat breath? 

High concentrations of hydrogen and methane gas detected in the breath have been linked with obesity in a new study at Ceders-Sinai Medical Center in Los Angeles.

The study analyzed the breath content of nearly 800 people and distinguished them by four breath types: people with normal breath content, those with higher concentrations of methane, those with higher concentrations of hydrogen, or people with high concentrations of both gasses.

Those with high concentrations of both methane and hydrogen were found to have higher body mass indexes and higher percentages of body fat, the study concluded.

While overeating and lack of exercise remain the primary causes of obesity, high concentrations of the microorganisms that produce methane and hydrogen may also be indicators of how susceptible a person is to developing obesity.

"This is the first large-scale human study to show an association between gas production and body weight - and this could prove to be another important factor in understanding one of the many causes of obesity", said lead author Dr. Ruchi Mathur, director of the Diabetes Outpatient Treatment and Education Center in the Division of Endocrinology at Cedars-Sinai.

A person exhales large amounts of hydrogen and methane gasses when a microorganism called Methanobrevibacter smithii colonizes the digestive tract. The organism is the dominate methane-producer in the human gut.

"Normally, the collection of microorganisms living in the digestive tract is balanced and benefits humans by helping them convert food into energy," said Mathur. "When M. smithii becomes overabundant, however, it may alter the balance in a way that makes the human host more likely to gain weight and accumulate fat."Mathur said in a press statement.

M. smithii produces methane by scavenging hydrogen from other microorganisms in the gut. Researchers theorize that the microorganismal interaction helps hydrogen-producing microorganisms extract nutrients from foods, which encourages weight gain in the human host.

The article, "Methane and Hydrogen Positivity on Breath Test is Associated with Greater Body Mass Index and Body Fat," appears in the April 2013 issue of Endocrine Society's Journal of Clinical Endocrinology & Metabolism.