Core Viewpoint - Urolithin A (UA) is a compound produced from foods rich in ellagitannins, such as pomegranates and raspberries, that activates mitophagy and improves mitochondrial health, showing potential in combating age-related immune decline and inflammation [3][4][7]. Group 1: Research Findings - A study published in Immunity demonstrated that UA can promote the expansion of T memory stem cells (Tscm), providing a rejuvenated immune system that can suppress cancer growth [3]. - A randomized, double-blind, placebo-controlled trial indicated that short-term oral administration of UA (1000 mg daily for 4 weeks) can regulate the composition and function of immune cells, supporting its potential against age-related immune decline [4][7]. - The trial involved 50 healthy middle-aged participants, with results showing that UA increased peripheral initial CD8+ T cells and improved their fatty acid oxidation capacity by 14.72 percentage points [7][8]. Group 2: Immune Cell Changes - UA treatment resulted in changes to the phenotype of CD8+ T cells, indicating a metabolic reprogramming of human immune cells [9][10]. - Enhanced mitochondrial biogenesis and an increase in peripheral blood CD56dim CD16bright NK cells were observed, along with improved TNF secretion and monocyte phagocytosis [11]. - Exploratory single-cell RNA sequencing revealed that UA drives transcriptional changes in immune cell populations, regulating pathways related to inflammation and metabolism [11][12]. Group 3: Overall Implications - Overall, the findings suggest that short-term supplementation of UA can modulate the composition and function of human immune cells, supporting its potential to counteract age-related immune decline and inflammatory aging [13].