The synbiotic studied in the four-week long trial consist of the probiotic strain Bifidobacterium animalis subsp. lactis GCL2505 and the prebiotic inulin.
Writing in Nutrients, the researchers reported that the resting energy expenditure of the intervention group was significantly higher – at 84.4 kcal more than the placebo group.
The findings showed that synbiotic supplementation could improve energy balance – a known major factor of obesity.
Resting energy expenditure is determined by summing the metabolic rates of body tissues. It accounts for about 60 per cent of the body’s energy expenditure.
Physical activity accounts for another 30 per cent, and diet-induced calorie loss accounts for the remaining 10 per cent.
“Our results indicated that the intake of GCL2505 and inulin improves energy balance, which is known to be a major factor of obesity, by modulating the microbiota in the gut.
“This is the first report to demonstrate the effects of probiotics and dietary fibre on REE (resting energy expenditure) in humans,” the researchers said.
The study involved 44 adults between 25 and 61 years old, with a BMI of between 25 and 30, and a body fat percentage of at least 15 per cent in men and 25 per cent in women.
They were randomised to take 10 billion CFU of GCL2505 and five grams of inulin daily or the placebo.
They were also provided accommodation at the testing facility to ensure that the trial took place in a controlled environment.
By the end of the study, resting energy expenditure of the intervention group was 1376.5 ± 272.8 kcal per day, significantly higher than the placebo group’s 1303.2 ± 188.1 kcal per day.
In fact, the resting energy expenditure of the intervention group was already significantly higher than the placebo group at week two of the trial – at 1435.9 ± 195.2 kcal per day versus 1345.5 ± 231.6 kcal per day.
However, no significant differences were seen between the two groups in terms of carbohydrate oxidation, lipid oxidation, and the ratio of carbohydrate to fat oxidation.
A previous study found that synbiotic could reduce visceral and body fat area.
Faecal bifidobacteria higher in intervention group
Faecal bifidobacteria counts were also significantly higher in the intervention group than the placebo group by the end of the trial.
Within the intervention group, the total number of bifidobacteria had significantly gone up from 10.5 ± 2.0 log cells/g faeces to 11.5 ± 0.9 log cells/g faeces.
In contrast, no significant changes were seen in the placebo group.
However, there were no significant differences between the two groups in terms of their faecal short-chain fatty-acids composition, including acetic and butyric acid concentrations.
This is with the exception of propionic acid, which was significantly lower in the intervention group as compared to the placebo group.
“This discrepancy can be explained by the detectable stability of SCFAs (short-chain fatty-acids) in the gut. The amount of SCFAs present in the faeces was known to be highly influenced by stool retention time and other factors, with large variations between individuals and between days,” the researchers explained.
No significant differences in BMI
No significant differences were also seen between the groups’ body weight, body mass index (BMI), body fat percentage, and muscle mass measurements.
The researchers pointed out that the amount of energy deficit required to lose one kilogram of body weight was around 7,400 to 7,700 kcal.
Based on this concept, the weight difference between the placebo and intervention group for this study will be about 0.3 kilograms.
The researchers recognised that “the change in values was too small to confirm intervention-induced changes in the body weight and BMI” of the intervention and placebo groups.
Nonetheless, they expect that the continued intake of the synbiotic would have a long-term optimising effect on body weight and BMI.
Source: Nutrients
Effect of Intake of Bifidobacteria and Dietary Fiber on Resting Energy Expenditure: A Randomized, Placebo-Controlled, Double-Blind, Parallel-Group Comparison Study
https://doi.org/10.3390/nu16142345
Authors: Baba, Y.; Azuma, N.; Saito, Y.; Takahashi, K.; Matsui, R.; Takara, T.
