Which Type of Vitamin K Is Best for Your Health?

November 15, 2025 •

3 min read

Vitamin K is not a single compound but a family of fat-soluble vitamins, primarily consisting of phylloquinone (K1) and a series of menaquinones (K2). While many people are aware of its vital role in blood clotting, the different types of vitamin K have unique properties that affect their bioavailability and function throughout the body, raising the question of which type is best for different health benefits.

Quick Summary

Vitamin K comes in two primary forms: K1 (phylloquinone) and K2 (menaquinones), with K2 having key subtypes like MK-4 and MK-7. Their distinct sources and physiological roles, particularly in bone and cardiovascular health, mean the best form depends on your specific health goals.

Key Points

Vitamin K1 for Blood Clotting: Primarily found in green leafy vegetables, vitamin K1 is essential for activating liver proteins responsible for blood coagulation.
Vitamin K2 for Bone and Heart Health: Found in fermented and animal products, K2 has a more widespread effect beyond the liver, notably promoting bone mineralization and inhibiting arterial calcification.
MK-7 Is Highly Bioavailable: The MK-7 subtype of K2, common in natto, has a longer half-life and superior bioavailability compared to K1 and MK-4, making it more effective for extrahepatic tissues.
MK-4 Requires Higher Doses: The MK-4 subtype of K2, found in animal fats, is cleared from the body much faster and is less bioavailable at nutritional doses, requiring much higher intake for extrahepatic effects.
Supplements Can Target Specific Needs: While a balanced diet provides vitamin K, supplements featuring K2 (especially MK-7) are often used to target specific bone or cardiovascular health goals due to their higher efficacy for these functions.
Consult a Doctor if Taking Warfarin: Consistent vitamin K intake is critical for those on blood thinners like warfarin, and supplementation should only be undertaken with a doctor's guidance.

What is Vitamin K?

Vitamin K, a crucial fat-soluble vitamin, is essential for several bodily functions, including blood coagulation and bone and heart health. There are two main naturally occurring forms of vitamin K: phylloquinone (K1) and menaquinones (K2). Vitamin K1 is predominantly sourced from plant-based foods, while vitamin K2 is found in fermented foods and animal products. Beyond these main distinctions, the numerous subtypes of K2, primarily MK-4 and MK-7, behave differently within the body.

Vitamin K1 vs. Vitamin K2: Understanding the Differences

Vitamin K1 (Phylloquinone): The Coagulation Specialist

Vitamin K1 is the most abundant dietary form, found in leafy green vegetables. It's primarily used by the liver for blood clotting. While essential, absorption from plant sources can be poor, improving with dietary fats. K1 has a short half-life.

Vitamin K2 (Menaquinones): The Extrahepatic Heavyweight

Vitamin K2 is a family of compounds from fermented foods and animal products. It plays a significant role in tissues outside the liver, particularly in bone and blood vessels, supporting bone mineralization and preventing arterial calcification. K2 has a longer half-life than K1, allowing it to circulate for days. Key forms include menaquinone-4 (MK-4) and menaquinone-7 (MK-7).

MK-4 vs. MK-7: The Most Important K2 Subtypes

MK-4 is found in animal products, has a short half-life, and requires high doses. MK-7, mainly from natto, has a long half-life (up to 72 hours), allowing for more consistent activation of K2-dependent proteins in bone and blood vessels, making it more effective for long-term health benefits.

Comparison of Vitamin K Forms


Feature	Vitamin K1 (Phylloquinone)	Vitamin K2 (MK-4)	Vitamin K2 (MK-7)
Primary Source	Leafy greens, plant oils	Animal products (eggs, meat, butter)	Fermented foods (natto, some cheeses)
Half-Life	Short (hours)	Short (hours)	Long (days)
Bioavailability	Lower, especially from vegetables	Lower at nutritional doses	Higher, accumulates in bloodstream
Main Function	Liver-based blood clotting	Extrahepatic functions, but requires large doses	Extrahepatic functions (bone, heart health)
Dosage	Adequate intake based on blood clotting needs	Requires higher, frequent doses for extrahepatic benefits	Effective at lower, once-daily doses
Best For	General daily intake, blood clotting maintenance	Specific tissue conversion, often via K1 or K2 precursors	Long-term bone and cardiovascular support

Specific Health Benefits: Which Type Is Best for What?

The best vitamin K type depends on your health goals, with K2, especially MK-7, showing advantages for bone and heart health.

For Bone Health

Vitamin K2, particularly MK-7, is effective for bone health by activating osteocalcin, which binds calcium to bone, improving density. Studies show MK-7 supplementation can improve bone quality.

For Heart Health

Vitamin K2 supports cardiovascular health by activating Matrix Gla Protein (MGP), which inhibits calcium buildup in arteries. Higher K2 intake is linked to reduced heart disease risk and arterial calcification, an effect not typically seen with K1. MK-7's long circulation is ideal for this.

For Other Health Benefits

Emerging research suggests K2 may offer other benefits, including potential anti-cancer properties, improved insulin sensitivity, and support for cognitive function.

Food Sources for Each Vitamin K Type

Include these foods for vitamin K:

Vitamin K1 Sources:

Leafy greens (kale, spinach)
Cruciferous vegetables (broccoli)
Certain vegetable oils

Vitamin K2 Sources:

MK-7: Natto
MK-4: Egg yolks, butter, liver
Other MKs: Some cheeses, kefir

Supplementation and Safety Considerations

Supplements are an option for those with insufficient dietary intake or specific health goals. K2, especially MK-7, is often in bone and heart health supplements. Vitamin K can interact with warfarin; consult a doctor if on anticoagulants before supplementing.

Conclusion

While K1 is vital for blood clotting, K2 (especially MK-7) is more effective for bone and cardiovascular health due to its better bioavailability and longer half-life. The best type depends on individual needs, but MK-7 is most efficient for long-term bone and artery support. A varied diet is ideal, and supplementation should be discussed with a healthcare professional.

Check out the NIH Office of Dietary Supplements for more health information on vitamin K.

Note: People taking blood thinners like warfarin should maintain consistent vitamin K intake and consult their doctor before starting any supplement.

Frequently Asked Questions

Vitamin K1 (phylloquinone) is found in plant foods and is mainly used by the liver for blood clotting. Vitamin K2 (menaquinones) is found in fermented foods and animal products and is more active in extrahepatic tissues, supporting bone and heart health.

MK-7 has a much longer half-life (up to 72 hours) and higher bioavailability compared to MK-4, which is cleared from the body in just a few hours. This means MK-7 provides a more consistent level of vitamin K to tissues for bone and cardiovascular benefits with a lower, once-daily dose.

MK-7, a form of vitamin K2, is generally considered the best for bone health. Its long half-life allows it to consistently activate osteocalcin, a protein that directs calcium to bones, which helps improve bone density and strength.

Vitamin K2, particularly MK-7, is highly regarded for its benefits to cardiovascular health. It activates proteins that prevent calcium from building up in the arteries, thereby reducing the risk of arterial calcification and heart disease.

Most people can meet their vitamin K requirements through a balanced diet, which provides a mix of K1 from plants and K2 from fermented foods or animal products. However, those with specific health concerns or poor absorption may benefit from supplementation after consulting a doctor.

The best dietary source of K2 (specifically MK-7) is the Japanese fermented soybean dish, natto. Other sources of K2 (including MK-4) include egg yolks, cheese, butter, and organ meats.

Vitamin K supplements are generally safe, with no established upper limit for most people. However, it is extremely important for those on blood thinners like warfarin to consult their doctor before taking supplements, as a sudden change in intake can affect medication effectiveness.