Thursday, 30 January 2014

Probiotics and Weight Loss - Is There a Relationship?

Researchers from Laval University in Quebec report that obese women who went on a diet and took a specific probiotic lost almost twice as much weight as those who went on the diet without taking the probiotic. The study involved 125 obese men and women. Interestingly, the probiotic had no effect on the amount of weight lost by the men.

Natural sauerkraut contains beneficial microorganisms or
probiotics; photo by MaxStraeten at
Scientists have previously observed that obese and lean people have a different combination of bacteria living in their large intestine and that these bacteria can influence human lives in various ways. The Laval scientists wanted to see if they could deliberately alter the gut environment and thereby create a beneficial health effect.

The men and women in the study followed a weight loss diet for twelve weeks followed by a weight maintenance program for another twelve weeks. Half of the people received two probiotic tablets a day throughout the experiment while the other half were given placebo tablets. A placebo contains a harmless but ineffective substance. The test subjects didn't know which type of tablets they were taking.

The human mind can sometimes have a powerful effect on health. The use of a placebo in an experiment enables researchers to decide whether any beneficial results are due to the test substance alone or to a psychological effect. Ideally, experiments with humans should be "double blind" experiments. In these experiments, the people giving the test substance and the placebo to the subjects don't know which type of substance they are administrating. This prevents any unconscious signals being given to the subjects.

The women receiving the probiotic in the Laval experiment lost weight throughout the whole 24 weeks of the experiment, although the weight loss was much lower during the weight maintenance diet. Each person lost a total of about 11 pounds. The women who received a placebo stopped losing weight during the weight maintenance diet and lost a total of about 6 pounds per person. Two additional discoveries were that the women in the probiotic group experienced a decline in the level of a hormone called leptin, which helps to regulate appetite, as well as a decrease in the population of gut bacteria that have been linked to obesity.

The results of the experiments are very interesting. The probiotic bacterium that was tested was a particular strain of Lactobacillus rhamnosus.  It would be good to know if other bacteria can have the same effect. In addition, the experiment needs to be done again with a much larger number of test subjects. An important puzzle that needs to be solved is why obese men failed to respond to the probiotic treatment.