The meta-analysis showed no significant effect of probiotics on body weight and body mass index (BMI).
The researchers from the Hoseo University and Keimyung University in South Korea warned though that quality data from rigorously designed randomised controlled trials (RCTs) had been limited and further research was needed to confirm the findings.
The initial data search yielded 368 articles – yet only four of these were RCTs comparing the efficacy of probiotics with a placebo and therefore included in the final meta-analysis. They added that the strains
used in the studies were not always clear. The probiotics used - mainly Lactobacillus species - were delivered in capsule and yoghurt form at similar dosages (1010 colony-forming units per day).
The big fat question
According to the World Health Organisation (WHO), worldwide obesity has more than doubled since 1980 with over 1.9 billion adults overweight in 2014. Of these more than 600 million were obese.
Obesity is largely associated with a mismatched energy balance – consuming more energy than is expended.
“However, changes in energy balance alone cannot explain the increased incidence of obesity. Recent human and animal studies have shown the intestinal microbiota to be a potential determinant of obesity,” the researchers wrote in the journal Nutrition Research.
It has been suggested that gut microbiota plays a role in energy harvesting, storage, and expenditure and the intestinal flora of obese people differs from ‘lean’ people – leading to the theory that a high fat diet alters microbiota.
Gut microbiota has also been shown to influence low-grade inflammation conditions like obesity and type 2 diabetes.
Last year a Nestlé-backed study published in the British Journal of Nutrition found evidence that certain probiotics containing Lactobacillus rhamnosus may help women lose and keep off weight.
Commenting on the results at the time, the company said: “The increased prevalence [of obesity] has led to intense research into the underlying causes, as well as programmes and therapies that may help prevent or manage the disorder. The causes are likely to be multifactorial and solutions may need to be tailored to the individual.”
Source: Nutrition Research
Vol 35, Iss 7, pp 566–575, doi:10.1016/j.nutres.2015.05.008
“Probiotics for weight loss: a systematic review and meta-analysis”
Authors: S. Park and J. Bae