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Vitamin K

FAT-SOLUBLE

Phylloquinone (K1), Menaquinones (K2)

Vitamin K encompasses a family of fat-soluble compounds that share a common 2-methyl-1,4-naphthoquinone ring structure. Its canonical function is as an essential cofactor for gamma-glutamyl carboxylase, which activates clotting factors II, VII, IX, and X in the liver. Beyond coagulation, vitamin K-dependent carboxylation is essential for osteocalcin (bone matrix protein) and matrix Gla protein (inhibits soft tissue calcification). Newborn infants are routinely given vitamin K at birth to prevent hemorrhagic disease.

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Key Functions

  • Blood clotting (activates coagulation factors)
  • Bone metabolism (osteocalcin carboxylation)
  • Inhibition of vascular calcification
  • Heart health via Matrix Gla Protein

Best Food Sources

Kale, spinach, and collard greensBroccoli and Brussels sproutsNatto (fermented soybeans)Fermented cheesesLiver

Deficiency: Vitamin K Deficiency

  • Easy bruising and bleeding
  • Nosebleeds and bleeding gums
  • Blood in urine or stool
  • Heavy menstrual bleeding
  • Osteoporosis risk

High-Risk Groups

  • Newborn infants
  • People on blood thinners (warfarin)
  • Those with malabsorption disorders

Reviewed for accuracy: Content is based on guidelines from the NIH Office of Dietary Supplements, Harvard T.H. Chan School of Public Health, and peer-reviewed medical literature.

Recommended Daily Amount

Adult Men

120 mcg

Adult Women

90 mcg

Did You Know?

Newborn infants are routinely given vitamin K at birth because vitamin K does not cross the placenta efficiently.

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