Kaloretta

Vitamin K: What It Does and How Much You Need

phylloquinone (K1), menaquinone (K2)

Vitamin K activates proteins needed for blood clotting and for binding calcium to keep bones strong. K1 is highest in leafy greens like spinach, parsley, and cabbage; K2 is found in fermented foods, hard cheeses, and liver.

Daily value

120 mcgmen90 mcgwomen

What it does

Vitamin K activates proteins that control blood clotting, as well as bone proteins that help bind calcium. Without enough vitamin K, these processes don't work as they should.

If you take warfarin

Warfarin and similar blood thinners work by blocking vitamin K. Sudden changes in how much vitamin K you eat can alter how well the drug works. Most doctors don't recommend cutting out leafy greens entirely — instead, try to eat roughly the same amount each day. Tracking your vitamin K intake in a food diary can help keep things consistent.

Where to find it

  • Leafy greens and vegetables: parsley, spinach, kale, broccoli, Brussels sprouts.
  • Plant oils (soybean, canola).
  • Fermented foods (natto, sauerkraut), hard cheeses, and liver — good sources of K2.

Daily values are US Dietary Reference Intakes for adults 19–50. Nutrient content of foods varies with variety and cooking method. This is general information and does not replace advice from a doctor or dietitian.