The study, published in the British Journal of Nutrition, aimed to determine whether the consumption of probiotics could help reset the balance of the intestinal microbiota in favour of bacteria that promote a healthy weight - finding that women who consumed probiotics of the species Lactobacillus rhamnosus in conjunction with a weight loss diet lost more weight than those who consumed a placebo and the weight loss diet. However, the team noted that this finding was only true in women, adding that there was no significant difference between placebo and the probiotic for weight loss in men.
Led by Professor Angelo Tremblay from the Université Laval, the team noted that previous studies have demonstrated that the intestinal flora of obese individuals differs from that of thin people, and that this difference may be due to the fact that a diet high in fat and low in fibre promotes certain bacteria at the expense of others.
"We don't know why the probiotics didn't have any effect on men. It may be a question of dosage, or the study period may have been too short," said Tremblay.
Tremblay and his colleagues recruited 125 overweight men and women who underwent a 12-week weight-loss diet followed by a 12-week period aimed at maintaining body weight.
Throughout the entire study half of the participants were given 2 pills daily containing probiotics from the Lactobacillus rhamnosus family, while the other half received a placebo.
After the 12-week diet period, researchers observed an average weight loss of 4.4 kg in women in the probiotic group and 2.6 kg in the placebo group. However, no differences in weight loss were observed among males in the two groups.
Upon completion of the 12-week maintenance period, the weight of the women in the placebo group had remained stable but the probiotic group had continued to lose weight, to a total of 5.2 kg per person, said Tremblay and his colleagues.
Indeed, by the end of the 24 week study women consuming probiotics lost twice as much weight as those receiving the placebo. The team also noted a drop in the appetite-regulating hormone leptin in this group, as well as a lower overall concentration of the intestinal bacteria related to obesity.
While the current study focused on only one strain of Lactobacillus rhamnosus, Tremblay noted that other probiotics found in dairy products could have a similar effect. He stressed, however, that the benefits of these bacteria are more likely to be observed in a favourable nutritional context that promotes low fat and adequate fibre intake.
Source: British Journal of Nutrition
Published online ahead of print, doi: 10.1017/S0007114513003875
"Effect of Lactobacillus rhamnosus CGMCC1.3724 supplementation on weight loss and maintenance in obese men and women"
Authors: Marina Sanchez, Christian Darimont et al