Torreya grandis Seeds and Their Processing Byproducts: Composition, Metabolic Health Benefits, and Multifunctional Bioactive Compounds—A Comprehensive Review

• Reviews T. grandis seeds composition and bioactivities for food and health applications. • T. grandis seeds are rich in sciadonic acid with health-promoting effects. • Sciadonic acid may modulate lipid metabolism and related chronic conditions. • Aril oil has antimicrobial and antioxidant potential for food and health. Torreya grandis seeds are an underutilized botanical resource rich in bioactive compounds, including lipids, proteins, carbohydrates, tocopherols, phytosterols, and phenolics, all of which offer diverse health benefits. This review critically examines the nutritional and functional properties of T. grandis nuts and their processing byproducts (e.g., arils, oil cake), with emphasis on their balanced ω-3/ω-6 fatty acid profile and metabolic regulatory potential. Key lipid constituents, particularly T. grandis seed oil (TGSO) and sciadonic acid (SA; 20:3 Δ-5,11,14), exhibit broad bioactivities, including anti-obesity, immunomodulatory, and neuroprotective effects. These effects are primarily mediated through oxidative stress reduction, suppression of proinflammatory cytokine, and modulation of lipid homeostasis. SA also shows therapeutic potential in improving insulin resistance, cognitive function, and bone remodeling. In addition, T. grandis processing byproducts show promise for multifunctional applications in food flavoring, antimicrobial packaging, and cosmetics. Despite substantial preclinical evidence supporting their metabolic and neurological benefits, human clinical validation remains limited. Future research should prioritize elucidating the structure-activity relationships of T. grandis -derived bioactive and developing advanced extraction and stabilization technologies to enhance their functional applications in nutraceutical and industrial contexts.