🔬 The science, kept simple
Vitamin K switches on the proteins that clot blood when you are cut, and a second set of proteins that steer calcium into bone and away from artery walls. K1 comes from leafy greens; K2 is made by bacteria and shows up in fermented foods like natto and in your own gut. It is fat-soluble, so a little oil on your salad helps it absorb.
Why you need it: Normal blood clotting, strong bones, and arteries that stay flexible instead of calcifying.
Daily target: About 120 mcg a day for men and 90 mcg for women.
📖 In Scripture
'The leaf thereof for medicine' (Ezekiel 47:12). The leafy greens Scripture pictures as food and healing are the richest vitamin K on the table.
🥇 Best food sources, ranked
- Kale ... about 1,060 mcg per cup, cooked
- Collard greens ... about 770 mcg per cup, cooked
- Spinach ... about 890 mcg per cup, cooked
- Swiss chard ... about 570 mcg per cup, cooked
- Natto (K2) ... about 850 mcg per 3.5 ounces
- Broccoli ... about 110 mcg per half cup, cooked
- Brussels sprouts ... about 110 mcg per half cup, cooked
- Prunes ... about 65 mcg per half cup
Figures are approximate, in the style of USDA FoodData Central; real foods vary with soil, variety, and cooking.
⚖️ Worth knowing
People taking warfarin must keep their green-vegetable intake steady from week to week rather than swinging up and down, because vitamin K works directly against that drug. Do not stop eating greens... just be consistent, and tell your doctor.
Matters most for
Educational information, not medical advice. Talk with your doctor before supplements, especially with kidney, thyroid, or heart conditions or in pregnancy.