Phylloquinone, commonly known as Vitamin K1, is a fat-soluble vitamin essential for human health, primarily involved in blood coagulation and bone metabolism. It functions as a cofactor for the enzyme gamma-glutamyl carboxylase, which activates proteins like prothrombin and osteocalcin by carboxylating glutamate residues. This compound is naturally synthesized by plants and is abundant in green leafy vegetables such as kale, spinach, and broccoli, as well as in vegetable oils. Chemically, it belongs to the naphthoquinone family and features a 2-methyl-1,4-naphthoquinone core with a phytyl side chain, making it lipophilic and stable under normal cooking conditions but sensitive to light and alkali. Vitamin K1 is crucial for preventing bleeding disorders and maintaining skeletal integrity, and it plays a role in modulating inflammation and cellular functions. Deficiency is rare in adults but can occur in newborns, leading to conditions like hemorrhagic disease. From a biochemical perspective, it is reduced to its active hydroquinone form in the liver to participate in the vitamin K cycle. Overall, it is a vital nutrient with antioxidant properties, distinguishing it from other forms like Vitamin K2. This description highlights its dietary sources, physiological roles, and stability characteristics, emphasizing its importance in nutrition and medicine.