What is the best version of vitamin K?

In a study comparing vitamin K1 and K2, it was found that menaquinone-7 (MK-7) significantly increased serum levels of vitamin K, while K1 and menaquinone-4 (MK-4) did not. This significant difference in absorption and bioavailability is a key factor when considering what is the best version of vitamin K for specific health goals.

Quick Summary

This article explores the distinct forms of vitamin K, examining the differences in bioavailability and function between K1, K2 (MK-4), and K2 (MK-7). It highlights the unique health benefits each provides, helping readers determine the most suitable option based on their nutritional needs.

Key Points

• Vitamin K comes in two main forms: K1 (phylloquinone) from plants and K2 (menaquinones) from fermented foods and animal products.

• K1 is crucial for blood clotting, but its poor absorption and short half-life limit its systemic effects.

• K2, especially the MK-7 subtype, has high bioavailability and a long half-life, making it more effective for extrahepatic tissues like bones and arteries.

• MK-7 supports bone health by activating proteins that direct calcium to bones, which can increase mineral density and strength.

• MK-7 promotes heart health by activating a protein that prevents arterial calcification and plaque buildup.

• A combination of vitamins K2 and D3 is often recommended, as they work together to ensure proper calcium distribution.

• Individuals on blood thinners like warfarin must consult a doctor before taking vitamin K supplements due to potential drug interactions.

Vitamin K is a fat-soluble vitamin essential for a number of vital bodily functions, most notably blood clotting, bone health, and cardiovascular health. While many people are generally aware of 'vitamin K,' it's actually a family of compounds with two primary naturally occurring forms: vitamin K1 (phylloquinone) and vitamin K2 (menaquinones). The question of what is the best version of vitamin K often depends on your specific health goals, as the different forms vary significantly in their absorption, transportation, and biological roles within the body.

The two primary forms of vitamin K

Vitamin K1 (Phylloquinone)

Vitamin K1 is primarily found in leafy green vegetables. It is rapidly used by the liver for blood coagulation, but has poor absorption from plants and a short half-life, limiting its availability for other tissues. Consuming K1 with fat can improve absorption.

Vitamin K2 (Menaquinones)

Vitamin K2 includes several subtypes (MK-4 to MK-13) and is found in fermented foods like natto (rich in MK-7) and some animal products (containing MK-4). K2 circulates longer in the blood than K1, making it more available for tissues outside the liver, such as bones and arteries.

K2 Subtypes: MK-4 vs. MK-7

MK-4, found in animal products, has a short half-life and requires high doses for systemic effects. MK-7, from fermentation, has a long half-life and remains available for days, making it more bioavailable and effective for extrahepatic tissues.

Why MK-7 is often considered the best option

MK-7's superior bioavailability and longer half-life make it highly effective for bone and cardiovascular health. It activates osteocalcin to direct calcium to bones and Matrix Gla Protein (MGP) to prevent arterial calcification. Research suggests MK-7 is more effective for heart health than K1.

Comparison Table: Vitamin K1 vs. K2 (MK-7)

Feature	Vitamin K1 (Phylloquinone)	Vitamin K2 (Menaquinone-7)
Primary Dietary Sources	Leafy greens (spinach, kale, broccoli)	Fermented foods (natto), certain cheeses, animal products
Absorption	Poor absorption from plant sources (less than 10%) unless consumed with fat	High absorption, especially from fermented foods and supplements
Half-Life in Blood	Very short (hours), rapidly cleared by the liver	Very long (days), remains in circulation longer
Primary Role	Liver-centric for blood coagulation (clotting) factors	Extrahepatic tissue-centric, supporting bone and cardiovascular health
Supplementation Efficacy	Inconsistent results for extrahepatic benefits	Highly effective for promoting bone and heart health

Choosing a vitamin K supplement

MK-7 is generally preferred for bone and cardiovascular health due to its bioavailability and long half-life. Supplements often combine K2 (MK-7) with vitamin D3 for synergistic calcium regulation. Always choose reputable brands. Consult a healthcare provider before taking vitamin K supplements if on blood thinners like warfarin, as it can interfere with their effectiveness.

Conclusion

While K1 is vital for blood clotting, MK-7 is the best version of vitamin K for long-term bone and cardiovascular health. Its superior absorption and circulation effectively support extrahepatic tissues, preventing arterial calcification and promoting bone mineralization. For comprehensive benefits beyond clotting, an MK-7 supplement or increased natto intake is recommended.

References

• Sato T, Schurgers LJ, Uenishi K. Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutr J. 2012;11:93. Published 2012 Nov 12. doi:10.1186/1475-2891-11-93
• Toshiro Sato, Natsumi Iwamoto, Takeshi Yamaoka. MK-7 and Its Effects on Bone Quality and Strength. PMC. 31 March 2020. doi:10.3390/ijms20040896
• MK4 & MK7 – The Two Forms of Vitamin K2 & The Differences. AlgaeCal Blog. 17 March 2025. https://blog.algaecal.com/the-two-forms-of-vitamin-k2-and-how-to-get-them/
• Lin, Steven. How to Choose the Right Vitamin K2 Supplement. Dr Steven Lin. 14 December 2017. https://www.drstevenlin.com/how-to-choose-the-right-vitamin-k2-supplement/
• Using the best form of Vitamin K: vitamin K1 vs MK-7. Feel. 18 November 2021. https://wearefeel.com/blogs/learn/forms-of-vitamin-k-k1-vs-k2-mk-7-menaquinone

Frequently Asked Questions

What is the primary difference between vitamin K1 and vitamin K2?

The main difference is their source, bioavailability, and half-life. Vitamin K1 is plant-based and mainly benefits the liver for blood clotting, while vitamin K2 is found in fermented foods and animal products, offering systemic benefits for bone and cardiovascular health due to its better absorption and longer half-life.

Which form of vitamin K is better for bone health?

Vitamin K2, specifically the MK-7 subtype, is considered superior for bone health. Its longer half-life allows it to better activate proteins like osteocalcin, which helps direct calcium to the bones, improving bone mineral density and strength.

Can I get enough vitamin K2 from my diet?

While vitamin K2 is found in certain foods like natto, cheeses, and egg yolks, its dietary intake can be inconsistent, and many Western diets contain very little of it. Therefore, many people may consider supplementation to ensure adequate intake for optimal bone and heart health.

Why are vitamin K2 supplements often paired with vitamin D3?

Vitamin D3 and K2 work together synergistically. Vitamin D3 helps with calcium absorption, while vitamin K2 ensures that the absorbed calcium is properly directed to bones and not deposited in soft tissues like arteries, promoting both bone and heart health.

Is there a difference between vitamin K2 MK-4 and MK-7?

Yes, MK-4 has a very short half-life and poor bioavailability at nutritional doses, whereas MK-7 has a significantly longer half-life and is more bioavailable, allowing it to provide more consistent systemic benefits.

Is it dangerous to take too much vitamin K?

There is no established upper intake level for the natural forms of vitamin K (K1 and K2) from foods or supplements, as they have a low potential for toxicity. However, individuals on blood-thinning medication should not increase their vitamin K intake without medical supervision.

What foods are rich in vitamin K2?

The richest source of K2 (MK-7) is natto (fermented soybeans). Other sources include cheeses (like Gouda and Brie), egg yolks, and organ meats, which primarily contain the MK-4 subtype.