Chlorogenic Acid Improves Intestinal Health in Largemouth Bass: Effects on Antioxidants, Inflammation, and Gut Microbiota
Dietary chlorogenic acid at 400 mg/kg favored intestinal antioxidant parameters, reduced pro-inflammatory gene expression, and altered gut microbiota composition in juvenile Micropterus salmoides compared to controls.
| Outcome | Grade | Direction | Effect | Studies |
|---|---|---|---|---|
| Intestinal SOD activity | D | ▲ Favorable | Aumento em G2 vs G0, valores exatos/IC NR | 1 |
| Intestinal MDA level | D | ▲ Favorable | Redução em G2 vs G0, valores exatos/IC NR | 1 |
| Pro-inflammatory gene expression (IL-1β, TNF-α, NF-κB) | D | ▲ Favorable | Redução em G2 vs G0, fold-change/IC NR | 1 |
| Anti-inflammatory gene expression (IL-10, TGF-β) | D | ▲ Favorable | Aumento em G2 vs G0, fold-change/IC NR | 1 |
| Intestinal morphology (villus height, crypt depth) | D | ▲ Favorable | Melhora em G2 vs G0, valores absolutos/IC NR | 1 |
| Gut microbiota composition (diversity and taxa) | D | ▲ Favorable | Aumento Firmicutes/Lactobacillus, redução Proteobacteria em G2; IC NR | 1 |
| Intestinal CAT activity | D | ▲ Favorable | Aumento em G2 vs G0, valores exatos/IC NR | 1 |
Context
Micropterus salmoides is a high-value species in Chinese aquaculture, but intensive conditions generate oxidative stress and intestinal dysbiosis. Plant-derived functional additives are investigated as alternatives to antibiotics to improve intestinal health in fish. Chlorogenic acid (CGA) has evidence in animal models, but data in largemouth bass under basal conditions were absent.
What the study showed
The G2 group (400 mg/kg CGA) showed higher intestinal SOD and CAT activities and lower MDA levels compared to controls; exact values and 95% CIs were not fully reported for all parameters. Pro-inflammatory gene expression (IL-1β, TNF-α, NF-κB) was reduced and anti-inflammatory genes (IL-10, TGF-β) were increased in G2 vs. G0. Intestinal morphology showed greater villus height and crypt depth in G2. Gut microbiota composition shifted, with increases in potentially beneficial taxa (Firmicutes, Lactobacillus) and decreases in Proteobacteria in G2.
How it was done
Controlled in vivo experimental study, not formally randomized, with 240 juveniles distributed into 4 groups (n=3 tanks/group, 20 fish/tank). Duration 70 days in a recirculating system. Distinct fish per tank were used for each analysis type (biochemistry/gene expression, histology, microbiota). Microbiota samples were pools of 3 individuals per tank.
Effect magnitude
Absolute effect sizes and 95% CIs were not systematically reported; differences between groups were expressed as means ± SD with statistical significance (p < 0.05), without standardized effect size calculation.
Limitations
Aquatic species study not extrapolable to humans; small sample (n=60 per group, 3 replicates/group); absence of 95% CIs and standardized effect sizes; no formal power calculation; microbiota based on pools rather than individual samples, reducing assessable variability; no risk of bias assessment using validated tools (RoB 2 or ROBINS-I); normal rearing conditions without pathogen challenge limit clinical extrapolation.
In clinical practice
This study does NOT support clinical application in humans. For Micropterus salmoides aquaculture, data suggest 400 mg/kg dietary CGA may be a dose of interest, but trials with larger n, pathogen challenge, and concrete productive outcomes are needed before any recommendation.
What is still missing
Trials with pathogen challenge, larger individual replicates for microbiota, evaluation of productive outcomes (FCR, weight gain, survival under challenge), and dose-response studies with 95% CIs in other aquaculture species of interest.