Coriander leaves () contain quercetin, a flavanol from the flavonoid polyphenol group that helps prevent various metabolic disorders. This study aimed to use HPLC-UV to investigate phenolic compounds in coriander leaves and their impact on nitrogen metabolism. Twenty-four healthy Wistar albino rats weighing 160 ± 10 g were divided into four groups: NC (no coriander), CT, CT, and CT. They received coriander leaf powder at levels of 12.2, 16, and 20.33 g/100 g of feed, respectively, based on the availability of quercetin on a dry matter (DM) basis. Feed intake was found higher in CT (27.27 g) and CT (25.43 g), while CT (24.96 g) and NC (24.66 g) showed a nonsignificant ( ≥ 0.05) trend; however, a similar trend was observed in weekly feed intake. After three weeks, rats in the CT group showed a 20 g reduction in body weight compared to the NC group (149.64 g vs. 163.41 g). The feed conversion and feed efficiency ratios (FCR & FER) were decreased in all treated groups due to the reduction in body weight (BW). The digestibility of DM and soluble carbohydrates was reduced in rats fed the CT diet while crude protein (CP), crude fiber (CF), ether extract (EE), and ash showed increasing trends. The rats that were fed different levels of coriander in the diet showed positive nitrogen balance. There was a reduction in serum uric acid in CT (0.72 ± 0.04 mg/dL) and CT (0.81 ± 0.03 mg/dL) as compared to other treatment groups. These nitrogen parameters had a positive impact on nitrogen metabolism, along with a significant ( ≤ 0.05) effect on total serum protein and a non-significant ( ≥ 0.05) effect on creatinine. Liver enzymes showed significant improvements in rats that were fed varying amounts of coriander powder. High-density lipoprotein (HDL) levels improved in all treatment groups, with a significant increase observed in CT (52.27 ± 0.27 mg/dL). In conclusion, 130 g of dry coriander containing 136 mg of quercetin can be effectively included in various food recipes in dry or wet form to improve serum indices and weight management in healthy people.