# Soy Isoflavones Mitigate High-Fat Diet-Induced Oxidative Stress and Inflammation in the Gut of Monopterus albus via Gut Microbiota Remodeling

## TL;DR

Adding soy isoflavones to high-fat diets in eels improves gut health by reducing oxidative stress and balancing gut bacteria.

## Contribution

This study shows that soy isoflavones can mitigate high-fat diet-induced gut damage in eels through microbiota remodeling.

## Key findings

- Soy isoflavones reduced intestinal damage and oxidative stress in eels on high-fat diets.
- Soy isoflavones improved antioxidant enzyme activity and gut microbiota balance.
- Soy isoflavones suppressed harmful bacteria and metabolic pathways in eel guts.

## Abstract

High-fat diets are often used in fish farming to reduce costs, but too much fat can harm their growth and health. This study explored whether adding soy isoflavones (SIFs), a natural phytic substance, to high-fat diets could help eels stay healthier. Researchers fed eels different diets: a normal-fat diet, a high-fat diet, and high-fat diet with two levels of SIFs. After eight weeks, eel on the high-fat diet showed signs of intestinal damage. However, dietary supplementation with SIFs boosted their ability to fight oxidative stress and inflammation. SIFs also help balance gut bacteria, reducing harmful microbes while promoting beneficial ones. These changes led to better digestion and overall health. The findings suggest that SIFs could be a valuable additive in eel farming, helping them thrive on high-fat diets while avoiding negative health effects. This could benefit farmers by improving eel production and quality, supporting sustainable aquaculture practices.

High-fat diets are commonly used in eel aquaculture to reduce protein costs, but excessive fat intake can impair intestine health. This study investigated whether soy isoflavones (SIFs), an emulsifying additive, could mitigate the negative effects of high-fat diets in eel. Six hundred eels (30.00 g) were randomly divided into four groups with three replicates: control (CK, 5.96% fat), high-fat diet (HFD, 11.96% fat), and HFD supplemented with 50 mg/kg (LSF) or 100 mg/kg SIF (HSF) for 8 weeks. Results show that SIF supplementation reversed adverse effects on eels fed high-fat diets, reducing intestine damage (better villi development and lower malondialdehyde levels) and improving antioxidant capacity (higher glutathione, p < 0.05). SIFs also increased key antioxidant-related enzyme activities (catalase, superoxide dismutase, p < 0.05). Gut microbiota analysis revealed that SIFs restored microbial balance by reducing Proteobacteria (Pseudomonas) and increasing Firmicutes (Lactococcus), while suppressing harmful metabolic pathways like lipopolysaccharide biosynthesis. These findings demonstrate that dietary SIFs (50 mg/kg) effectively counteract high-fat diet-induced intestine damage and gut dysbiosis in eels, offering a practical nutritional strategy for sustainable aquaculture.