Food colorant tartrazine causes weight loss in emerging-adulthood male rats correlated to microbiota dysbiosis

Our study investigated the effects of daily tartrazine consumption at acceptable daily intake (ADI) levels on gut microbiota composition, biochemical status, and body weight changes in pre-adult male and female Wistar rats. We hypothesized that tartrazine exposure would alter the gut microbiota and induce systemic metabolic stress, thereby influencing weight gain. For 12 weeks, six-week-old rats (n=32) received tartrazine dissolved in water at a dosage of 7.5 mg/kg/day or were administered water alone. Weekly body weights, fecal samples for 16S rRNA sequencing, and blood samples for biochemical analyses (ALT, GGT, GLU, TBLB), inflammation (CRP), oxidative biomarkers (total antioxidant status [TAS], total oxidant status [TOS], oxidative stress index [OSI]), and Paraoxonase 1 (PON1) activity were collected. Tartrazine-treated male rats showed significant reductions in weight gain from week 7 onward, with controls weighing ~44 g more by week 18. This slower weight gain correlated with marked microbiota dysbiosis, including a reduced Firmicutes/Bacteroidetes ratio (1.7 vs. 7.7 in controls), increased Proteobacteria and Gammaproteobacteria, and decreased Bacilli. The biochemical parameters supported these findings: mild elevations in ALT and GGT and decreased PON1 activity suggested microbiota-associated hepatic and metabolic stress, while increased TOS and OSI with reduced TAS indicated systemic oxidative stress. CRP levels were consistent with low-grade inflammation likely driven by dysbiosis and increased gut permeability. Furthermore, tartrazine-treated males exhibited a significant reduction in Shannon diversity index at week 18. In contrast, female rats displayed no significant weight changes but showed sex-specific microbiota shifts and subtle biochemical responses without the pronounced oxidative or inflammatory patterns observed in males. Overall, our findings indicate that tartrazine at ADI levels can alter gut microbial composition and systemic biochemical homeostasis in a sex-dependent manner, contributing to slowed weight gain and metabolic stress in pre-adult males. These results highlight the need to further explore tartrazine’s microbiota-driven metabolic effects during critical developmental periods. This research was supported by Atilim University Research Grant no: ATÜ-BAD-2122-03. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.