phylloquinones

Phylloquinone, also known as vitamin K1, is a fat-soluble vitamin that plays a essential role in the gamma-carboxylation of certain glutamate residues in blood coagulation proteins and other vitamin K–dependent proteins. It is the primary dietary form of vitamin K in humans and is predominantly found in green leafy vegetables and some vegetable oils, with smaller amounts in other plant foods. Phylloquinone is produced by photosynthetic organisms and enters the human diet through plant-derived foods.

Sources and absorption are influenced by fat intake, as phylloquinone is absorbed with dietary lipids via the small intestine and transported in chylomicrons. It is stored in the liver and other tissues as part of the body’s fat-soluble vitamin pool and undergoes enterohepatic circulation. Conditions that impair fat absorption, such as fat malabsorption syndromes, celiac disease, or certain pancreatic disorders, can reduce phylloquinone status.

Biological role includes serving as a cofactor for gamma-glutamyl carboxylase, which activates several vitamin K–dependent proteins. In coagulation, this enables factors II, VII, IX, and X, and regulatory proteins C and S, to bind calcium and function properly. Phylloquinone also affects bone and vascular health through proteins such as osteocalcin and matrix Gla protein.

Dietary reference and deficiency: in adults, adequate intake is about 120 micrograms per day for men and 90 micrograms per day for women. Deficiency is rare in developed countries but can occur with fat malabsorption or prolonged antibiotic use and is a concern for newborns, who may be given vitamin K at birth. Warfarin and other anticoagulants interact with vitamin K by antagonizing its action, so stability of intake is advised.