Vitamin K is essential for blood clotting and bone health, but not all forms are created equal. The two primary types, Vitamin K1 and Vitamin K2, play distinct roles in the body. Understanding their differences can help you make informed dietary and supplement choices to support your overall health.
Vitamin K1: The Clotting Specialist
Vitamin K1, also known as phylloquinone is predominantly found in leafy green vegetables like spinach, kale, and broccoli. Its main function is to activate proteins involved in blood coagulation, which prevents excessive bleeding. However, it has a short half-life and is quickly cleared from the bloodstream, limiting its availability to other tissues.
Vitamin K2: The Bone and Heart Guardian
Vitamin K2, or menaquinone, exists in several subtypes, most notably MK-4 and MK-7. Unlike K1, K2 is found in fermented foods (like natto and sauerkraut) and animal products (such as egg yolks and cheese). It plays a key role in calcium metabolism, directing calcium to your bones and teeth, and preventing it from building up in arteries and soft tissues.
One subtype, MK-7, has a long half-life—up to 72 hours—allowing for more consistent absorption and use throughout the body, particularly in the bones and cardiovascular system.
Comparing Vitamin K1 and K2
| Feature | Vitamin K1 | Vitamin K2 (MK-4, MK-7) |
| Primary Function | Blood clotting | Bone and cardiovascular health |
| Sources | Leafy greens | Fermented foods, animal products |
| Half-life | Short (hours) | Long (up to 72 hours for MK-7) |
| Tissue Focus | Liver-focused | Reaches bones and arteries |
| Calcium Regulation | Limited | Highly effective |
Dietary Sources of Vitamin K2
You can increase your Vitamin K2 intake with these foods:
- Natto – A Japanese fermented soybean dish, extremely high in MK-7.
- Hard cheeses – Such as Gouda and Edam.
- Egg yolks and liver – Especially rich in MK-4.
- Sauerkraut – Offers both K2 and gut-friendly probiotics.
- Chicken – A moderate source of MK-4.
Should You Supplement Vitamin K2?
For those who don’t consume many fermented foods or animal products, a K2 supplement, especially MK-7, can be a valuable addition. It’s longer lasting and better absorbed than K1. However, always consult your healthcare provider, especially if you’re taking blood thinners, as Vitamin K can interfere with medication.
The Bottom Line
While both Vitamin K1 and K2 are essential, they serve different purposes. K1 is the clotting specialist, while K2 act like your body’s calcium concierge, directing it to the right places and keeping your arteries clear. By incorporating more K2-rich foods or supplements, you support your bones, teeth, and heart more effectively.
