Beijing, Aug 6 (IANS): Prolonged spaceflight may effect changes in the bacteria residing inside the gut, making astronauts vulnerable to inflammatory bowel diseases, says a new study.

"Our study provides useful insights on the cross-regulation of the mucosal immune system, epithelial barrier and commensal bacteria not only in humans in spaceflight or analog, but also in humans on earth that undergo various stresses," said study author Qing Ge from Peking University Health Science Center in Beijing.

To make their discovery, Ge and colleagues used four groups of mice.

Two groups of mice were suspended for 14 days by the tail at a 15 degree head-down tilt with their hindlimbs suspended.

Access to food and water was ensured using both water bottles and gel packs and food distributed around the floor of the cage.

Animals demonstrated no adverse effects or pronounced weight loss.

Tho other groups were normal.

The researchers found that when mice were subjected to spaceflight-like conditions, the balance of bacteria and the function of immune cells in the gut changed, leading to increased bowel inflammation.

"We already know that a trip to Mars and back may well have serious, possibly permanent, effects on the bodies of the astronauts," said Gerald Weissmann, editor-in-chief of The FASEB Journal where the study was published.

"Now we learn that the hidden passengers on that mission -- the bacteria in their gut --will be affected as well. This lends further credence to the fact that life on Earth, including the microbiome, evolved under gravity and needs it to thrive," Weissmann noted.