How effective are the gut microbiome-based interventions for the management of overweight or obesity in children and adolescents in all their diversity, aged 0 to 19 years?
Key messages
• It is unclear if gut microbiome-based interventions (nutrition interventions targeting intestinal microbes) have an effect on body mass index (BMI), body weight, waist size, body fat percentage, measures of blood pressure, and adverse events in children and adolescents with overweight and obesity.
• Further research, including larger trials, is required to understand the effects of gut microbiome-based interventions for the management of overweight and obesity in children and adolescents.
What is overweight or obesity?
Overweight is a condition of excessive fat deposits, and obesity is a chronic disease characterised by excessive fat deposits that can affect most body systems, impair quality of life, and reduce life expectancy. BMI, calculated by dividing a person's weight in kilograms by their height in metres, squared, is often used to define overweight and obesity.
How is overweight or obesity managed?
Overweight or obesity may be managed through changes in diet, behavioural counselling for lifestyle modifications, medications, or surgery. Despite these approaches, this global epidemic affects more than 390 million children and adolescents aged 5 to 19 years, and 37 million children under five years of age as of 2022. Overweight or obesity is linked to abnormal metabolism and an imbalance in the gut microbiome. Published works have shown that nutrition interventions targeting the "gut microbiome" may have beneficial effects on body weight and body fat percentage. The gut microbiome is the community of harmless bacteria and other microorganisms in the human intestine needed for optimal health.
What did we want to find out?
We wanted to find out the effect of various nutritional interventions targeting the intestinal microbial community on BMI, body weight, waist circumference, total body fat percentage, blood pressure, and adverse events associated with the interventions amongst children and adolescents in all their diversity, aged 0 to 19 years.
What did we do?
We searched for studies that examined the effects of gut microbiome-based interventions, including prebiotics (food ingredients that promote beneficial microbes in the gut), probiotics (live microbes that are good for health), synbiotics (a combination of both prebiotics and probiotics), short-chain fatty acids (i.e. small fat molecules produced by intestinal bacteria by fermenting dietary fibre and non-digestible carbohydrates), and faecal microbiota transplantation (i.e. a capsule containing stool microbes from a healthy donor), compared to standard-of-care (usual care), placebo, control, or no interventions in children and adolescents up to 19 years of age. We compared and summarised the results of the studies and rated our confidence in the evidence based on factors such as study methods and sizes.
What did we find?
We found 17 studies involving 838 children and adolescents with overweight and obesity. The studies were conducted in different countries, including Spain, China, Taiwan, Canada, Mexico, Italy, Poland, Turkey, Iran, Thailand, Denmark, New Zealand, and the USA.
Adolescents aged 10 to 19 years
Nutrition interventions targeting intestinal microbes may have little to no effect on BMI, body weight, waist size, body fat percentage, blood pressure, and adverse events, but the evidence is very uncertain.
Children and adolescents aged 0 to 19 years
It is unclear if prebiotics have an effect on waist size, body fat percentage, blood pressure, and adverse events compared with a dummy treatment. One study found that prebiotics compared to a dummy treatment (i.e. an intervention that does not contain any medicine but looks or tastes identical to the intervention being tested) may result in a small reduction in BMI and body weight, but the evidence is very uncertain.
Probiotics compared to a dummy treatment may have little to no effect on BMI, body weight, waist size, body fat percentage, blood pressure, and adverse events, but the evidence is very uncertain.
It is unclear if synbiotics have an effect on BMI, body weight, waist size, body fat percentage, diastolic blood pressure, and adverse events compared with a dummy treatment. One study found that synbiotics may result in a reduction in systolic blood pressure, but the evidence is very uncertain.
It is unclear if short-chain fatty acids have an effect on body weight, body fat percentage, blood pressure, and adverse events compared with a dummy treatment. One study found that short-chain fatty acids may result in a reduction in BMI and waist circumference, but the evidence is very uncertain.
Side effects of the interventions were generally not reported in the included studies, but one study noted potential side effects such as abdominal cramps, abdominal discomfort, abdominal pain, diarrhoea, vomiting, and migraine in the prebiotics group; however, the occurrence was very low. Nausea and headache were reported in another study in the short-chain fatty acids group, but were minimal.
What are the limitations of the evidence?
The review's findings are limited by the small number of participants, the low number of available studies for each of the comparisons, the lack of long-term data, and insufficient reporting of adverse effects.
How up to date is this evidence?
The evidence is current to January 2025.
Read the full abstract
The epidemic of overweight and obesity affects more than 390 million children and adolescents aged 5 to 19 years and 37 million children under five years of age. Overweight and obesity are associated with both short- and long-term consequences, including chronic inflammation, metabolic diseases, as well as alterations in the gut microbiome composition. Gut microbiome-based approaches may impact microbiome-related metrics such as diversity or the abundance of intestinal bacteria, which may be linked to obesity-related outcomes. However, evidence regarding the effect of gut microbiome-based interventions for the management of obesity is limited.
Objectives
To assess the effects of gut microbiome-based interventions in the management of overweight or obesity in children and adolescents in all their diversity aged 0 to 19 years.
Search strategy
We searched CENTRAL, MEDLINE, CINAHL, Web of Science Core Collection, BIOSIS Previews, Global Index Medicus (all regions), IBECS, SciELO, PAHO, PAHO IRIS, WHO IRIS, WHOLIS, Bibliomap, TRoPHI as well as ICTRP Search Portal and ClinicalTrials.gov. The date of the last search for all databases was 24 January 2025. We did not apply any language restrictions.
Selection criteria
We included randomised controlled trials that evaluated gut microbiome-based interventions [i.e. prebiotics, probiotics, synbiotics, short-chain fatty acids (SCFAs), and faecal microbiota transplantation (FMT)] compared to standard-of-care, placebo, or control interventions in children and adolescents aged 0 to 19 years with overweight or obesity.
Data collection and analysis
Two review authors independently screened titles and abstracts and full texts, extracted data, and assessed the risk of bias using the Cochrane Risk of Bias 2 tool and certainty of the evidence using Grading of Recommendations Assessment, Development and Evaluation (GRADE), a framework for assessing the certainty of evidence and making recommendations in systematic reviews. Random-effects meta-analyses were performed unless only one study per outcome was available, for which fixed-effect analyses were performed.
Main results
We found 17 studies (838 participants) from various countries, evaluating the effects of prebiotics, probiotics, synbiotics, SCFAs, and FMT on body mass index (BMI), body weight, waist circumference, total body fat percentage (%TBF), systolic and diastolic blood pressure, and adverse events. Of the 17 studies included, five studies were in adolescents aged 10 to 19 years, and 12 studies were in children and adolescents spanning both age groups, 0 to 19 years. Upon contacting authors for data grouped by age of the participants, no studies provided separate outcomes data for children and adolescents. The included studies were funded by either academic funding sources or grants from the public and private sectors. Additionally, 15 studies were classified as currently being conducted ('ongoing').
The certainty of evidence throughout was very low.
In adolescents 10 to 19 years of age, probiotics compared to placebo or no intervention may have little to no effect on BMI, body weight, waist circumference, %TBF, blood pressure, and adverse events. Similarly, FMT compared to placebo may have little to no effect on waist circumference, %TBF, blood pressure, and adverse events in this age group.
According to one study with 41 participants and in children and adolescents 0 to 19 years of age, intervention with prebiotics compared to placebo may result in a small reduction in BMI (mean difference = -0.70, 95% CI = -1.25 to -0.15) and body weight (mean difference = -1.5, 95% CI = -2.61 to -0.39). Prebiotics compared to placebo may have little to no effect on waist circumference, %TBF, systolic blood pressure, and adverse events. No data were available on the effect of prebiotics on diastolic blood pressure.
Probiotics compared to placebo may have little to no effect on BMI, body weight, waist circumference, %TBF, blood pressure, and adverse events in children and adolescents (0 to 19 years).
Synbiotics compared to placebo may result in a reduction in systolic blood pressure (mean difference = -40.00, 95% CI = -50.63 to -29.37) in children and adolescents (0 to 19 years); according to one study with 56 participants. The evidence is very uncertain about the effects of synbiotics compared to a placebo on BMI, body weight, waist circumference, blood pressure, and adverse events. No data were available on the effect of synbiotics compared to placebo on %TBF. Synbiotics, compared to probiotics, may have little to no effect on waist circumference, %TBF, and adverse events. No data were available on the effect of synbiotics compared to probiotics on BMI, body weight, and blood pressure.
According to one study with 48 participants and very low-certainty of evidence, SCFAs compared to placebo may result in a reduction in waist circumference (mean difference = -5.08, 95% CI = -7.40 to -2.76) and BMI (mean difference = -2.26, 95% CI = -3.24 to -1.28) in children and adolescents (0–19 years). SCFAs compared to placebo may have little to no effect on adverse events. No data were available on the effect of SCFAs on body weight, %TBF, and blood pressure.
Adverse events, i.e. abdominal cramps, abdominal discomfort, abdominal pain, diarrhoea, vomiting, and migraine, were reported in the prebiotics group but with very low incidence. Additionally, adverse events such as nausea and headache were reported in the SCFAs group, but with low incidence.
Authors' conclusions
In adolescents aged 10 to 19 years, gut microbiome-based interventions may result in little to no difference in obesity-related outcomes. In children and adolescents aged 0 to 19 years, prebiotics may result in a small reduction in BMI and body weight; synbiotics may result in a reduction in systolic blood pressure, and SCFAs may result in a reduction in BMI and waist circumference, albeit the certainty of evidence was very low. The evidence was of very low certainty due to few studies per comparison, small sample sizes, short intervention durations, and insufficient reporting of adverse events. More rigorous research examining different types of gut microbiome-based interventions for the management of obesity is required in children and adolescents, both in clinical and community settings. Future trials should also report methods related to randomisation, blinding, and compliance, as well as include prespecified analysis plans.
