They decrease the activity of bile acidsEven if you cannot see them, there are billions of bugs swarming around you, on you and in you. An yogurt introduces billions of bacteria into your gut and the "probiotics" ones standing in your intestines are believed to alleviate many issues from bowel disease to allergies. A new research published in the Molecular Systems Biology and carried out on mice has found that "probiotic" food can change metabolism and even induce weight loss.
Our gut contains about 1000 species of microorganisms, and this sophisticated flora appears to be involved in human health and weight control. In 2007, Jeremy Nicholson, a biochemist at the Imperial College London, together with a team and the Nestlé Research Center in Lausanne, Switzerland, revealed that changing the mice's gut flora with human microbes triggered serious metabolic changes in the rodents.
In the new research, Nicholson's team added to the diet of mice harboring human gut microbes a solution with two probiotic species of Lactobacillus bacteria, common in yogurt and baby formula. Control individuals received just a saline solution. Two weeks later, the mice's metabolism was checked by investigating samples of feces, urine, plasma, intestinal contents, and liver tissue.
Even if the gut flora changed very little in all mice groups, this was not the case of the metabolic rate, betrayed by various markers like blood cholesterol and amino acid levels in the liver.
"Of particular note was the effect of probiotics on bile acids, which help the small intestine absorb fat. Probiotics diminished the function of the acids, which may make it harder for the animals to absorb fat--and thus should keep them slim," Nicholson said.
Just two foreign microbes impacted so deeply because bacteria inter-communicate, believe the authors.
"Gut bacteria talk to each other, so despite their relatively modest numbers, probiotics have a huge effect on what those other bugs do," said Nicholson, who warns that mice have simpler guts than humans.
"We can't change human genetics, but if we can alter metabolism with minor changes in gut bacteria, that's very exciting," Glenn Gibson, a microbiologist at Reading University, UK, not involved in this research, said.