was ist vitamin k3 — can a microbiome test help?

Vitamin K3 (menadione) is a synthetic form of vitamin K that is not approved for human consumption due to potential toxicity (e.g., oxidative stress, hemolysis). Unlike vitamin K1 (phylloquinone) and K2 (menaquinone), K3 is mainly used in animal feed. A microbiome test cannot directly assess vitamin K3 status, but it can identify bacterial strains that produce vitamin K2 (e.g., certain Bacteroides species). However, evidence for clinically meaningful K2 production by the gut microbiome is limited and highly individual. Therefore, a microbiome test is not helpful for managing vitamin K3 – especially since K3 is not recommended as a supplement. For vitamin K concerns, focus on dietary K1/K2 sources and consult a healthcare professional.