# Trace minerals, antioxidant defense, and safe consumption of Nile tilapia: insights from ecological variability in lake Mariout, Egypt

## TL;DR

Nile tilapia from restored basins in Lake Mariout, Egypt, are safe to eat and nutritious, with no non-carcinogenic health risks.

## Contribution

The study evaluates trace mineral accumulation, antioxidant enzyme activity, and gene expression in Nile tilapia from restored basins.

## Key findings

- Nile tilapia from Lake Mariout show no non-carcinogenic health risks at consumption rates of 100–500 g per day.
- B2 fish exhibit higher antioxidant enzyme activities and upregulated metal-regulatory and antioxidant defense genes.
- Fish from B1 have higher protein and carbohydrate content compared to B2.

## Abstract

Trace minerals are essential components of fish that contribute to human nutrition and food security. In this study, Nile tilapia (Oreochromis niloticus) were collected from two restored basins of Lake Mariout, Egypt—the Main Basin (B1) and the Southwest Basin (B2)—to evaluate trace mineral accumulation, antioxidant enzyme activity, proximate composition, gene expression, and potential human health risks. Metal concentrations in fish tissues followed the order Fe > Ca > Zn > Cu, with Cu showing significant variation between basins. Human health risk assessment, including estimated daily intake (EDI), estimated weekly intake (EWI), and maximum daily intake (MDI), indicated no non-carcinogenic risk at consumption rates of 100–500 g per day. Proximate analysis showed that B1 fish had higher protein and carbohydrate content, whereas B2 fish exhibited significantly higher antioxidant enzyme activities. Gene expression analysis revealed upregulation in B2 fish of metal-regulatory genes—metallothionein (mt1), divalent metal transporter 1 (dmt1), zinc transporter 1 (znt1), hepcidin 2 (hepc2)—and antioxidant defense genes—superoxide dismutase 1 (sod1), catalase (cat), glutathione peroxidase 1 (gpx1), glutathione reductase (gr), and glutamate-cysteine ligase catalytic subunit (gclc). Overall, Nile tilapia from the restored basins of Lake Mariout represent a nutritionally adequate and safe food source, highlighting the benefits of effective environmental management.

The online version contains supplementary material available at 10.1038/s41598-025-34419-z.