Vitamin K

Gamma-glutamyl carboxylase uses vitamin K as a cofactor so prothrombin and factors VII, IX, and X can bind calcium and finish the clotting cascade. Spinach, choy sum, and broccoli are everyday phylloquinone sources. People who bruise easily, bleed at the gums, and almost never eat greens should first check whether this hepatic carboxylation path is left empty by the diet.

Osteocalcin can bind hydroxyapatite only after carboxylation; matrix Gla protein then binds surplus calcium crystals in vascular smooth muscle. Natto and other fermented foods bring long-chain menaquinones; leafy phylloquinone is taken up first by the liver. With few greens and few fermented soy foods, both bone matrix and vessel walls lack this carboxylation feedstock.

Beyond clotting, vitamin K-dependent proteins also join inflammation control and cell-proliferation signaling; leafy greens and fermented soy foods supply different vitamin K forms. People who eat very little greens long term—outside anticoagulant use—are also asked about this immune-related carboxylation path, beyond bone and vessels.