Which is the Best Vitamin K1 or K2 for Your Health?

November 15, 2025 •

2 min read

According to a 2019 review, research suggests that the body absorbs significantly more vitamin K2 (especially the MK-7 subtype) than vitamin K1, profoundly affecting how each functions in the body. Navigating the differences can be complex, so understanding which is the best vitamin K1 or K2 for your specific needs is crucial for targeted health benefits.

Quick Summary

Vitamin K exists as two main types, K1 and K2, with distinct functions and sources. While K1 is primarily involved in blood clotting and is found in leafy greens, K2 is better absorbed, stays in the body longer, and is more effective for bone and cardiovascular health. Food sources include fermented foods and some animal products for K2, and supplements are available for both.

Key Points

Functional Distinction: Vitamin K1 primarily supports blood clotting via liver proteins, while Vitamin K2 is more effective for non-liver functions like bone and cardiovascular health.
Superior Bioavailability: Vitamin K2, specifically the MK-7 subtype, has a longer half-life and is absorbed more efficiently by the body than K1, allowing it to act on extra-hepatic tissues.
Targeted Health Benefits: K2 is specifically noted for its role in regulating calcium to promote bone mineralization and inhibit arterial calcification, providing superior benefits for long-term bone density and heart health compared to K1.
Different Food Sources: K1 is abundant in leafy greens, while K2 is found in fermented foods (natto, some cheeses) and animal products (egg yolks, liver).
Potential for Supplementation: Due to the low absorption of K1 from plants and the scarcity of high-K2 foods in Western diets, supplementation, particularly with K2 (MK-7), is a practical option for optimizing levels.
Blood Thinners and Safety: Individuals on anticoagulant medication like warfarin must be cautious with their vitamin K intake and always consult a doctor before changing their diet or starting supplements.

Vitamin K: The Difference Between K1 and K2

Vitamin K is a family of fat-soluble vitamins essential for functions like blood clotting, bone health, and cardiovascular wellness. The two main forms are vitamin K1 (phylloquinone) and vitamin K2 (menaquinones). They differ in sources, absorption, and roles, leading to the question: which is the best vitamin K1 or K2?

Vitamin K1: The Coagulation Specialist

Vitamin K1 is abundant in green leafy vegetables and is the primary form in a typical Western diet. Its main role is in blood coagulation, activating liver proteins necessary for clotting. K1 has low absorption from plants and a short half-life.

Vitamin K2: The Bone and Heart Protector

Vitamin K2 includes menaquinone subtypes (MKs), notably MK-4 and MK-7. K2 is better absorbed and has a longer half-life than K1, allowing it to benefit tissues beyond the liver, such as bones and blood vessels. K2 activates osteocalcin for bone mineralization and Matrix GLA protein to prevent calcium buildup in arteries.

Why K2 is often considered 'better' for specific functions

Research indicates K2 is more effective than K1 for bone and heart health. K2 improves bone mineral density and reduces fracture risk. It also inhibits arterial calcification, linked to a lower risk of coronary heart disease. K1's action is more liver-focused, making it less effective for these non-hepatic benefits.

Comparison Table: Vitamin K1 vs. K2


Feature	Vitamin K1 (Phylloquinone)	Vitamin K2 (Menaquinones)
Primary Source	Leafy green vegetables (e.g., spinach, kale, broccoli)	Fermented foods (natto, cheese), animal products (egg yolks, liver)
Absorption Rate	Low bioavailability (less than 10% absorbed from plants)	Higher bioavailability (especially MK-7)
Half-Life in Body	Short (hours)	Long (days, especially MK-7)
Main Function	Blood clotting (liver activity)	Bone mineralization & cardiovascular protection (extra-hepatic)
Key Activated Proteins	Coagulation factors	Osteocalcin (bone) and MGP (vascular)

A note on dietary considerations and supplementation

Despite K1's presence in vegetables, its poor absorption makes it hard to achieve optimal levels for systemic effects through diet alone. High-K2 foods like natto are not common in Western diets, and other sources have lower amounts. Supplementation with K2, particularly MK-7, is thus a popular option, especially for bone density or preventing arterial stiffening. Those on blood thinners like warfarin must consult a doctor before changing K intake due to potential interactions.

Conclusion: The Verdict on Which is Best

The choice between vitamin K1 and K2 depends on the desired health outcome. K1 is essential for blood clotting and rapid liver action. However, K2 is better for long-term bone strength and cardiovascular health due to better absorption and longer circulation. A balanced diet and potential K2 supplementation, after professional consultation, can contribute to overall wellness. Both forms are part of a complete nutritional strategy.

London Osteoporosis Clinic: The vital role of vitamin K in health

Frequently Asked Questions

Vitamin K1 primarily functions in the liver to activate proteins necessary for blood coagulation. Vitamin K2 focuses on extra-hepatic tissues, activating proteins that manage calcium for healthy bones and arteries, preventing arterial calcification.

Vitamin K2 is significantly more effective than K1 for bone density. It activates osteocalcin, a protein that binds calcium to the bone matrix, thereby promoting bone mineralization and strengthening bones.

Yes, vitamin K2 is particularly beneficial for heart health. It activates Matrix GLA Protein (MGP), which prevents calcium from depositing in the arteries and soft tissues, thus inhibiting arterial calcification associated with heart disease.

Vitamin K1 is mainly found in leafy green vegetables such as spinach, kale, and broccoli, as well as in other plants like Brussels sprouts and certain fruits.

The richest sources of K2 include natto (fermented soybeans), certain cheeses (Gouda, Brie), egg yolks, and organ meats like liver. The MK-7 form of K2 is particularly abundant in fermented foods.

While K1 is common in diets, its low absorption rate might necessitate supplementation for some. K2 is often deficient in Western diets due to uncommon food sources, making K2 supplementation, especially with the MK-7 subtype, a common practice for bone and cardiovascular health.

No, it is not safe to take Vitamin K supplements without consulting a doctor if you are on blood-thinning medication like warfarin. Vitamin K can interfere with the medication's effectiveness, requiring dose adjustments.