Comparative Evaluation of Different Fruit Parts of Phyllanthus emblica L. for Functional Food Applications: Nutritional Composition, Safety, and Gut Microbiota-Associated Aging Benefits

Population aging has increased interest in food-based strategies to support healthy aging. <i>Phyllanthus emblica</i> L. (<i>P. emblica</i>) is an edible fruit widely used in functional food products; however, the nutritional characteristics, safety, and functional differentiation of its distinct fruit parts generated during processing remain unclear. In this study, four anatomical parts of <i>P. emblica</i> (the whole fruit, P), juice powder (PJP), pomace (PP), and seed-containing core (PC) were systematically evaluated for nutritional composition, antioxidant activity, safety, and anti-aging potential using a D-galactose-induced aging mouse model. Results show that the <i>P. emblica</i> juice powder (PJP) retained the most favorable nutritional characteristics and exhibited superior antioxidant capacity. A clear efficacy gradient was observed (PJP > P > PP > PC), with PJP showing the most pronounced improvements in aging-associated functional outcomes and redox and inflammatory status. Given the role of the gut-brain axis in aging-related regulation, gut microbiota composition and short-chain fatty acids (SCFAs) production were further analyzed. PJP selectively enriched beneficial bacteria, including <i>Akkermansia</i> and <i>Alistipes</i>, and increased SCFA levels, particularly propionic acid and isovaleric acid. In contrast, the seed-containing core raised safety concerns, characterized by hepatotoxicity and elevated serum aminotransferases. Overall, this study establishes a clear hierarchy of efficacy and safety among <i>P. emblica</i> fruit parts and supports the rational selection of juice powder for functional food development targeting healthy aging.