Integrated Assessment of the Functional Activity of the Gut Environment and Metabolic Profiles in Rats Fed an Insect-Based (Tenebrio molitor) Diet
A 35% Tenebrio molitor meal diet increased fecal enzyme activity (β-glucuronidase and β-glucosidase) and decreased fecal SCFA concentrations (acetate, butyrate, valerate) compared to a chicken hydrolysate diet, while reducing fecal water genotoxicity over 8 weeks.
| Population | Rattus norvegicus rats (monogastric preclinical model) |
|---|---|
| Exposure | Diet containing 35% T. molitor meal (Group A) |
| Comparator | Chicken hydrolysate diet (Group B) and standard laboratory diet (Group C) |
| Outcome | Fecal β-glucuronidase activity; Fecal butyrate concentration; Fecal acetate concentration; Fecal water genotoxicity; Fecal β-glucosidase activity; Fecal formic acid concentration; Fecal valeric acid concentration |
Summary of findings
| Outcome | Effect | 95% CI | Certainty | Clinical relevance | Notes |
|---|---|---|---|---|---|
| Fecal β-glucuronidase activity | F=78.62, p<0.0001, partial eta2=0.79 (Group A highest vs B and C) | — | Very low | — | 1 studies |
| Fecal butyrate concentration | F=31.94, p<0.000001, partial eta2=0.60 (Group A lower: 11.38-26.06 mg/g vs Group B: 15.75-95.57 mg/g) | — | Very low | — | 1 studies |
| Fecal acetate concentration | F=25.13, p<0.000001, partial eta2=0.54 (Group A lower: 12.17-15.97 mg/g vs Group B: 31.58-49.03 mg/g) | — | Very low | — | 1 studies |
| Fecal water genotoxicity | F=27.40, p<0.001, partial eta2=0.57 (Group A ~6-fold reduction by week 6; Group B highest at week 8 vs A and C, p<0.001) | — | Very low | — | 1 studies |
| Fecal β-glucosidase activity | F=22.57, p<0.001, partial eta2=0.52 (Group A highest: 0.00299-0.00405 vs Group B: 0.00131-0.00189 and Group C: 0.00138-0.00162 mmol/mg protein) | — | Very low | — | 1 studies |
| Fecal formic acid concentration | F=23.43, p<0.000001, partial eta2=0.53 (Group A lowest: 11.71-17.17 mg/g vs Group B: 24.02-39.36 mg/g and Group C: 19.48-31.12 mg/g) | — | Very low | — | 1 studies |
| Fecal valeric acid concentration | F=11.71, p=0.000091, partial eta2=0.27 (Group A lowest: 5.86-8.16 mg/g vs Group B: 26.29-44.52 mg/g and Group C: 18.44-35.95 mg/g) | — | Very low | — | 1 studies |
Context
Insect-based diets are gaining traction as sustainable protein alternatives for monogastric animals. Few studies have simultaneously assessed intestinal functional biomarkers (SCFAs, fecal enzymes, genotoxicity) and systemic metabolomics in response to high-inclusion insect diets. Prior data on fecal water genotoxicity following T. molitor consumption in mammals were absent.
What the study showed
β-glucuronidase activity was consistently highest in Group A (0.000571–0.000883 mmol/mg protein) versus Groups B and C (0.000200–0.000434 and 0.000221–0.000366 mmol/mg protein; F=78.62, p<0.0001, ηp²=0.79). Acetate and butyrate concentrations were lower in Group A (acetate: 12.17–15.97 mg/g; butyrate: 11.38–26.06 mg/g) than in Group B (acetate: 31.58–49.03 mg/g; butyrate: 15.75–95.57 mg/g). Fecal genotoxicity in Group A decreased approximately 6-fold by week 6 and remained low at week 8; Group B maintained significantly higher genotoxicity than Groups A and C at week 8 (p<0.001).
How it was done
In vivo experimental study with rats assigned to three dietary groups for 8 weeks. Feces were collected at multiple time points for SCFA analysis by chromatography, enzymatic activity by colorimetric assays, and genotoxicity by comet assay in HT29 cells. Liver and spleen metabolomics were performed by methods not fully specified in the available text. Exact sample size per group was not reported in the provided excerpt.
Effect magnitude
Group effect on β-glucuronidase was large (ηp²=0.79); on butyrate, ηp²=0.60 (F=31.94, p<0.000001); on fecal genotoxicity, ηp²=0.57 (F=27.40, p<0.001). Individual 95% CIs for most SCFA outcomes were not provided in the text.
Risk of bias
Animal model (rats) with no established direct applicability to humans. Sample size per group not reported in the available excerpt, preventing power assessment. No formal risk-of-bias tool (e.g., SYRCLE for animal studies) was mentioned. Liver and spleen metabolomics were insufficiently detailed in the analyzed excerpt for full critical appraisal of systemic outcomes.
What this study does NOT prove
This study does not prove that T. molitor diets are safe or beneficial for humans or companion animals; findings are restricted to a rodent model under controlled conditions. It does not establish causality between specific dietary components (chitin, protein, lipids) and the observed outcomes.
In clinical practice
Results do not support direct clinical recommendations; this is a preclinical rodent study. Animal nutrition professionals and researchers may use these data to design studies in target species (dogs, cats, pigs, poultry). The elevation of β-glucuronidase in the T. molitor group requires evaluation in longer-duration studies before any risk inference.
Limitations
Animal model (rats) with no established direct applicability to humans. Sample size per group not reported in the available excerpt, preventing power assessment. No formal risk-of-bias tool (e.g., SYRCLE for animal studies) was mentioned. Liver and spleen metabolomics were insufficiently detailed in the analyzed excerpt for full critical appraisal of systemic outcomes.
What is still missing
Studies in clinically relevant target species (e.g., dogs, pigs) and humans are needed to confirm effects on SCFAs, genotoxicity, and systemic metabolism. Mechanisms by which T. molitor chitin modulates colonic fermentation and genotoxicity need elucidation.
Technical appendix
Version history
- 1.0 · 2026-09-23 — Auto-generated under Evidence Standard v1.0