Metabolome × Microbiome Changes Associated with a Diet-Induced Reduction in Hepatic Fat among Adolescent Boys

Abstract

Dietary sugar reduction is one therapeutic strategy for improving nonalcoholic fatty liver disease (NAFLD), and the underlying mechanisms for this effect warrant further investigation. Here, we employed metabolomics and metagenomics to examine systemic biological adaptations associated with dietary sugar restriction and (subsequent) hepatic fat reductions in youth with NAFLD. Data/samples were from a randomized controlled trial in adolescent boys (11–16 years, mean ± SD: 13.0 ± 1.9 years) with biopsy-proven NAFLD who were either provided a low free-sugar diet (LFSD) (n = 20) or consumed their usual diet (n = 20) for 8 weeks. Plasma metabolomics was performed on samples from all 40 participants by coupling hydrophilic interaction liquid chromatography (HILIC) and C18 chromatography with mass spectrometry. In a sub-sample (n = 8 LFSD group and n = 10 usual diet group), 16S ribosomal RNA (rRNA) sequencing was performed on stool to examine changes in microbial composition/diversity. The diet treatment was associated with differential expression of 419 HILIC and 205 C18 metabolite features (p < 0.05), which were enriched in amino acid pathways, including methionine/cysteine and serine/glycine/alanine metabolism (p < 0.05), and lipid pathways, including omega-3 and linoleate metabolism (p < 0.05). Quantified metabolites that were differentially changed in the LFSD group, compared to usual diet group, and representative of these enriched metabolic pathways included increased serine (p = 0.001), glycine (p = 0.004), 2-aminobutyric acid (p = 0.012), and 3-hydroxybutyric acid (p = 0.005), and decreased linolenic acid (p = 0.006). Microbiome changes included an increase in richness at the phylum level and changes in a few genera within Firmicutes. In conclusion, the LFSD treatment, compared to usual diet, was associated with metabolome and microbiome changes that may reflect biological mechanisms linking dietary sugar restriction to a therapeutic decrease in hepatic fat. Studies are needed to validate our findings and test the utility of these “omics” changes as response biomarkers.

Lipidome Changes Associated with a Diet-Induced Reduction in Hepatic Fat among Adolescent Boys with Metabolic Dysfunction-Associated Steatotic Liver Disease

“…Hepatic DNL was significantly decreased in the treatment group (from 34.6% to 24.1%) versus the control group (33.9% to 34.6%) (adjusted week eight mean difference: −10.6% (95% CI: −19.1%, −2.0%)) and body weight decreased slightly (from 91.1 to 89.7 kg) in the treatment group [24]. Furthermore, our previous metabolomics and metagenomics analysis revealed differential changes in the microbiome and metabolome, including amino acid and lipid species associated with the diet treatment and improvement in hepatic steatosis [25].…”

“…Intervention, N = 20 1 Control, N = 20 In subsequent studies of data/samples from this parent trial, we reported the effects of the 8-week dietary treatment on hepatic DNL measured using a metabolic labeling protocol with heavy water [24] and on metabolomics and metagenomics profiles [25]. For the present study, which was designed as a follow-up study to build on these previous analyses, high-resolution lipidomics (both untargeted and targeted) were performed on stored plasma samples to assess the differential lipidome changes that occurred with the LFSD treatment.…”

“…A diet low in free sugars (restricted to <3% of daily caloric intake) for eight weeks resulted in a significantly greater reduction in hepatic steatosis (from 25% at baseline to 17% at week 8) compared to a usual diet (21% to 20%) [23], in parallel with a greater reduction in hepatic DNL [24]. To gain a deeper understanding of the biological changes associated with this diet treatment-induced reduction in hepatic steatosis, we performed high-resolution metabolomics and metagenomics on fasting plasma samples collected at baseline and study completion during the trial [25]. Our analysis revealed changes in key metabolic pathways, including several lipid pathways, such as omega-3 and linoleate metabolism, which may reflect improved oxidative stress and inflammation [25].…”

“…To gain a deeper understanding of the biological changes associated with this diet treatment-induced reduction in hepatic steatosis, we performed high-resolution metabolomics and metagenomics on fasting plasma samples collected at baseline and study completion during the trial [25]. Our analysis revealed changes in key metabolic pathways, including several lipid pathways, such as omega-3 and linoleate metabolism, which may reflect improved oxidative stress and inflammation [25]. Additionally, previous studies comparing metabolome profiles of children with and without MASLD have also identified distinct differences in the presence of certain glycerophospholipids, including lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) species [26].…”

The Impact and Burden of Dietary Sugars on the Liver

“…The analyses revealed that the low free sugar diet, compared to the usual diet, was associated with metabolome and microbiome changes that may reflect biological mechanisms linking dietary sugar restriction to a therapeutic decrease in hepatic fat. 132 …”