Researchers in Thailand studied the impact of inulin supplementation in obese children by analysing samples from a study trial, and by conducting in vitro studies, both of which show that inulin boosts Bifidobacterium, which improves muscle health and reduces inflammation among the study participants.
“Inulin supplementation promoted the muscle biomarkers in agreement with fat-free mass gain, elucidating by Bifidobacterium metabolites derived from inulin digestion showed in vitro anti-inflammatory activity and decreased systemic pro-inflammation, thus promoting muscle production via gut-muscle axis response,” said the researchers in Nature: Scientific Reports.
At present, obesity is seen as a condition involving chronic inflammation. A component from certain bacteria, lipopolysaccharide (LPS), is believed to trigger this inflammation. When LPS crosses the gut barrier, it causes inflammatory responses by interacting with immune cells in fat tissue, leading to the production of inflammatory substances. High-fat diets, common among obese children, increase LPS absorption and contribute to inflammation. Poor gut health, with fewer beneficial bacteria like Bifidobacterium, worsens this.
Inulin, a well-researched prebiotic, has been shown to increase Bifidobacterium levels and improve various health markers in obese individuals, such as reducing body weight and fat, improving satiety, and lowering blood sugar and insulin levels after meals. The improvement in gut bacteria from inulin is believed to reduce inflammation and enhance anti-inflammatory activity.
Bifidobacterium can use inulin to produce short-chain fatty acids (SCFAs), which have health benefits.
The researchers hypothesise that these SCFAs and other metabolites from Bifidobacterium can promote muscle development by enhancing muscle cell growth, energy production, blood flow, and protein storage.
To explore this, the researchers examined how inulin supplementation affects muscle mass in obese children by analysing data from a randomised double-blinded placebo-controlled trial (RCT) that was conducted from August 2017 to July 2020 at the King Chulalongkorn Memorial Hospital, Thailand.
The participants – Thai children aged 7–15 years with obesity – were randomly assigned to one of three groups: inulin supplement (inulin extracted from Jerusalem artichoke), a placebo (maltodextrin), or dietary fibre advice. All participants received monthly follow-up with the same standard advice of dietary intake and exercise for six months.
The stored plasma and serum samples from the RCT of inulin supplementation in obese children were analysed for biomarkers of muscle building at the first and sixth visits.
For the muscle building biomarkers analysis, blood samples from the RCT were analysed to measure muscle building markers at the start and end of the study. Fifty-six samples were analysed.
A specific protein (myokine IL-15) was measured, and the markers creatinine/cystatin C ratio were also analysed.
Researchers also studied how inulin and Bifidobacterium affect muscle building.
Bifidobacterium was grown with either glucose or inulin, and the resulting substances were tested on immune cells (macrophages) in the lab. The macrophages were exposed to various conditions – with or without LPS – to measure changes in gene expression and inflammatory markers.
In the clinical phase of the study, two indicators of muscle health – IL-15 and the creatinine/cystatin C ratio – significantly improved over six months in children who took inulin.
“In clinical phase, IL-15 and creatinine/cystatin C ratio significantly increased from baseline to the 6th month. In vitro study showed that metabolites derived from Bifidobacterium capable of utilising inulin contained the abundance of SCFAs,” said the researchers.
For the lab findings, researchers found that Bifidobacterium bacteria, which thrive on inulin, produced SCFAs that reduced harmful inflammation markers (TNF-α, IL-6, IL-1β, and iNOS) and increased beneficial anti-inflammatory markers (FIZZ-1 and TGF-β).
“In the presence of LPS, treatment from Bifidobacterium + inulin downregulated TNF-α, IL-6, IL-1β, and iNOS, but upregulated FIZZ-1 and TGF-β expression. Inulin supplementation promoted the muscle biomarkers in agreement with fat-free mass gain, elucidating by Bifidobacterium metabolites derived from inulin digestion showed in vitro anti-inflammatory activity and decreased systemic pro-inflammation, thus promoting muscle production via gut-muscle axis response.”
The study shows that giving inulin to children with obesity significantly increased indicators of muscle growth and lean body mass. This effect can be attributed to the anti-inflammatory properties of substances produced by Bifidobacterium when they digest inulin as shown in the lab studies.
“Those metabolites may decrease systemic pro-inflammation, thus promoting muscle production in children with obesity via gut-muscle axis response. To bolster these results, future studies incorporating inulin alongside multi-strain probiotics may uncover further insights into the interaction between gut microbiota and muscle health in children with obesity,” concluded the researchers.
Source: Nature: Scientific Reports
DOI: https://doi.org/10.1038/s41598-024-61781-1
“Inulin supplementation exhibits increased muscle mass via gut-muscle axis in children with obesity: double evidence from clinical and in vitro studies”
Authors: Chonnikant Visuthranukul, Asada Leelahavanichkul et al.
