Nutrient glossary
What is vitamin K?
Vitamin K activates the proteins that clot blood and bind calcium into bone; leafy greens are its home ground.
Reviewed 20 July 2026. General information, not medical advice.
The short version
The K is from "Koagulation": without vitamin K your blood cannot clot. It also activates the proteins that lock calcium into bone rather than soft tissue, which ties it into long-term bone strength.
Kale, spinach, chard and broccoli are dense in K1, and your gut bacteria plus fermented foods add K2. It is fat-soluble, so greens dressed with oil deliver more of it.
Daily reference
75 µg a day
The reference scales with body weight at about 1 µg per kg a day, so 75 µg for a 75 kg adult. People on warfarin should keep intake steady rather than low, with their care team.
This is the fixed adult reference used across these pages. In the app, your amount adjusts to your body and way of eating.
Best food sources of vitamin K
Full ranking| Food | Per serving | Per 100g |
|---|---|---|
| Swiss Chard | 299 µg | 830 µg |
| Spinach | 290 µg | 483 µg |
| Broccoli (cooked) | 220 µg | 141 µg |
| Parsley | 164 µg | 1,640 µg |
| Kale | 164 µg | 390 µg |
| Collard Greens | 157 µg | 437 µg |
| Brussels Sprouts | 156 µg | 177 µg |
| Mixed Salad Greens | 119 µg | 140 µg |
Common questions
- Can I eat leafy greens on blood thinners?
- On warfarin the goal is a steady vitamin K intake, not avoidance; sudden changes in either direction shift the dose response. Newer anticoagulants do not interact with vitamin K.
- What is the difference between K1 and K2?
- K1 from greens handles clotting; K2, made by bacteria and found in fermented foods and some animal foods, appears more active in bone and blood vessels.