Vitamin K
Body function
Blood clotting (coagulation factor synthesis); bone mineralisation; supports arterial health
Daily requirement
90 mcg/day (women), 120 mcg/day (men)
Deficiency signs
Easy bruising, prolonged bleeding from cuts, blood in urine or stool (rare in adults without an underlying condition)
Excess risks
Very low toxicity from food or K1/K2 supplements; may interact with blood-thinning medication such as warfarin
At-risk groups
People on long-term antibiotics, those with fat malabsorption disorders (coeliac disease, Crohn's disease), newborns
Supplement forms
Vitamin K1 (phylloquinone), Vitamin K2 (menaquinone, MK-4/MK-7 forms)
Food sources
- Spinach (cooked) — ~888 mcg vitamin K per cup cooked (very high — nearly 10x daily need)
Educational information only — not medical advice. This content does not diagnose, treat, or replace consultation with a qualified healthcare professional. Always seek professional medical advice for symptoms, supplement use, or health concerns.