Camellia japonica, widely appreciated as an ornamental plant, has recently attracted interest for its leaves as a potential source of nutritional and bioactive compounds. This study investigated the nutritional composition, total phenolic content (TPC), and antioxidant capacity of C. japonica leaves to assess their functional food potential. Nutritional analysis showed that the leaves contain 4.19% protein and 2.90% lipids, suggesting a low-fat, plant-based protein source. The total phenolic content (TPC), quantified using the Folin–Ciocalteu assay, was 36.67 ± 4.05 mg GAE/g dry weight, reflecting a substantial abundance of polyphenolic compounds.

Antioxidant activity, assessed via DPPH and ABTS radical scavenging assays, yielded IC₅₀ values of 33.11 ± 7.25 µg/mL and 23.75 ± 10.97 µg/mL, respectively, demonstrating notable antioxidant potential. These findings suggest that C. japonica leaves have both nutritional and functional value, supporting their potential use in the development of health-oriented food products. A promising application would be the formulation of a functional or fermented beverage such as kombucha, using C. japonica leaf extracts. These products could deliver natural antioxidants and polyphenols to consumers, offering benefits related to oxidative stress reduction and general well-being. Additionally, using leaves from ornamental pruning supports circular economy strategies and sustainable ingredient sourcing.

In conclusion, C. japonica leaves, traditionally underutilized, exhibit significant potential as a novel ingredient in the functional food sector. Their integration into plant-based beverages represents an innovative, sustainable approach to valorizing horticultural byproducts while contributing to the development of antioxidant-rich dietary options.