Vitamin K metabolism and nutriture

Area of Science:

• Biochemistry
• Human Nutrition
• Hematology

Background:

• Vitamin K is vital for post-translational carboxylation of glutamate residues to gamma-carboxyglutamate (Gla) in coagulation factors and bone proteins like osteocalcin.
• Understanding vitamin K metabolism is crucial for human health and disease prevention.

Purpose of the Study:

• To review recent advances in vitamin K metabolism and its role in human nutrition.
• To highlight new methodologies for assessing vitamin K status and understanding its physiological significance.

Main Methods:

• Utilized new methodologies to measure endogenous vitamin K concentrations and plasma levels of des-gamma-carboxyprothrombin (PIVKA-II).
• Employed biochemical assays to study vitamin K sources, absorption, transport, storage, and transplacental transfer.
• Reviewed existing literature on vitamin K's role in coagulation, bone health, and interactions with medications.

Main Results:

• Refined indices for assessing human vitamin K status have been developed.
• The importance of phylloquinone (vitamin K1) versus menaquinones (vitamins K2) for human needs is being clarified.
• Subclinical vitamin K deficiency, particularly in newborns, and its associated risks (hemorrhagic disease) are better understood.
• Insights into the mechanism of coumarin anticoagulants and vitamin K antagonism by other compounds (e.g., antibiotics) have emerged.
• Potential effects of vitamin K deficiency on non-hepatic Gla-proteins and calcium homeostasis are being investigated.

Conclusions:

• Improved biochemical monitoring enhances the assessment of vitamin K status and deficiency risks.
• A deeper understanding of vitamin K's complex roles in coagulation, bone metabolism, and potential drug interactions is evolving.
• Further research into non-hepatic Gla-proteins and calcium homeostasis may reveal additional functions of vitamin K.