What is the best vitamin K2?

November 12, 2025 •

3 min read

According to a 2021 review in Open Heart, vitamin K2 supplementation has shown promising potential for improving cardiovascular health outcomes. So, what is the best vitamin K2 for your specific health goals, and how do you choose from the various forms available?

Quick Summary

This article explains the different forms of vitamin K2, comparing MK-7 and MK-4 for bioavailability and effectiveness. It details food sources, provides dosage guidance, and outlines what to consider when selecting a high-quality supplement to support bone and heart health.

Key Points

MK-7 is superior for daily supplementation: Due to its high bioavailability and long half-life, MK-7 is the most effective form for consistent, nutritional support of bones and arteries.
MK-4 requires higher, more frequent doses: The short half-life and poor bioavailability at nutritional levels mean that for general supplementation, MK-4 is less efficient than MK-7.
Look for naturally derived MK-7: Opt for MK-7 produced through natural fermentation (e.g., from natto or chickpeas) to ensure high purity and a potent bioactive all-trans form.
Combine with vitamin D3 for synergy: For optimal bone and cardiovascular health, take vitamin K2 alongside vitamin D3, as they work together to regulate calcium metabolism.
Avoid K2 if on warfarin (blood thinners): Vitamin K2 can interfere with anticoagulant medications like warfarin; consult a doctor before supplementing if you are on blood thinners.
Check for third-party testing: Reputable brands provide third-party verification to ensure purity and potency, confirming the stated dosage and form.
Dietary sources are limited: While foods like natto, certain cheeses, and egg yolks contain K2, a supplement can be the most reliable way to ensure adequate intake.

Understanding the Forms of Vitamin K2

Vitamin K2, also known as menaquinone (MK), is a fat-soluble vitamin vital for calcium metabolism, bone density, and cardiovascular health. While vitamin K1 (phylloquinone) is known for its role in blood clotting, K2 is responsible for activating specific proteins that manage calcium in the body, directing it to bones and teeth and away from arteries. Vitamin K2 is a group of molecules called menaquinones, differentiated by a number (e.g., MK-4, MK-7) based on their side chain length. The most common and supplemented forms are MK-4 and MK-7, which differ significantly in function and bioavailability.

MK-4: The Short-Chain Menaquinone

MK-4 is a short-chain K2 found in animal products like egg yolks and high-fat dairy. It is synthesized in the body from other vitamin K forms. MK-4 is highly bioactive but has a short half-life, requiring higher, more frequent doses. It is rapidly taken up by tissues like the brain and arteries. Effective doses for bone health in studies are often pharmacological, much higher than typical supplements.

MK-7: The Long-Chain Menaquinone

MK-7 is a long-chain menaquinone found notably in natto and some cheeses. It boasts high bioavailability and a long half-life, staying in the blood for up to 72 hours. This allows for smaller daily doses to be effective. MK-7 effectively reaches tissues like bones and blood vessels to activate key proteins. High-quality MK-7 is primarily in the bioactive trans form.

Natural vs. Synthetic Vitamin K2

The source of vitamin K2 impacts quality and activity. Naturally derived MK-7, typically from fermentation of natto or chickpeas, yields a highly bioactive all-trans form without harsh chemical solvents. MK-4 is usually synthetic, though structurally identical to what the body produces. Synthetic MK-7 is also available but may contain less active cis isomers. Look for high-purity, all-trans MK-7 when choosing a supplement.

Comparison Table: MK-4 vs. MK-7


Feature	MK-4 (Menaquinone-4)	MK-7 (Menaquinone-7)
Source	Animal products, converted from K1	Fermented foods, supplements
Bioavailability	Low at nutritional doses	High; longer presence in blood
Half-Life	Very short (hours)	Long (up to 72 hours)
Effective Dose	High, often pharmacological	Low, nutritional
Purity Concerns	Mainly synthetic	Synthetic versions may have inactive cis isomers
Optimal Use	Targeted therapy (under medical supervision)	Effective daily supplementation

Key Factors for Choosing the Best Vitamin K2

To determine the best vitamin K2 for your needs, consider the following:

Form: MK-7 for Daily Supplementation. MK-7 is generally the superior choice for daily bone and cardiovascular support due to its high bioavailability and long half-life at nutritional doses.
Dosage: Effective daily doses of MK-7 are typically 90-180 mcg, significantly lower than MK-4 dosages used in studies.
Source: Prioritize naturally fermented MK-7, often from natto or chickpeas, ensuring a high percentage of the all-trans isomer (ideally 99%+). Third-party testing can verify purity.
Combination with Vitamin D3: These vitamins work synergistically; D3 aids calcium absorption, and K2 directs it to bones and teeth, away from arteries. Many quality supplements combine them.
Quality and Purity: Research brand manufacturing. Look for USP standards and consider sourcing from reputable regions.
Avoidance on Warfarin: If taking anticoagulants like warfarin, avoid vitamin K2 supplements without strict medical supervision, as they can interfere with medication.

Conclusion: Making the Right Choice

For most individuals seeking daily support for bone and heart health, a naturally derived, high-purity MK-7 is the best vitamin K2. Its superior bioavailability, long half-life, and effectiveness at nutritional doses make it the optimal choice. While MK-4 is active in tissues, its rapid clearance and high dosage needs make it less suitable for general use. Choose a supplement based on quality sourcing, the trans-MK-7 form, and consult a healthcare provider if you have health conditions or take medication.

How to Select the Right Vitamin K2 Supplement

Read the Label: Look for 'Menaquinone-7 (MK-7)' and 'all-trans'.
Verify the Source: Choose natural fermentation (natto/chickpeas).
Check for Third-Party Testing: Ensures purity and dosage.
Assess Purity Claims: High-quality MK-7 is typically 99%+ all-trans.
Consult Your Doctor: Essential if on blood thinners like warfarin.
Consider a D3 Combination: For maximized calcium benefit.
Evaluate Dosage: Aim for 90-180 mcg daily for nutritional support.

Frequently Asked Questions

For most people seeking daily supplementation, MK-7 is the best form. It has superior bioavailability and a longer half-life, meaning it remains active in your body for longer periods at lower doses. MK-4 has a very short half-life and requires much higher doses to be effective.

While there is no official Recommended Dietary Allowance (RDA), a common and effective dose for MK-7 supplements is between 90 and 180 micrograms (mcg) per day. For MK-4, the effective doses used in studies are typically much higher, often in the milligram range.

Getting sufficient vitamin K2 from diet alone is difficult for most people, especially in Western diets. The richest source is natto, a fermented Japanese food, which is not commonly consumed. While some K2 is found in high-fat dairy, eggs, and organ meats, a supplement is often the most reliable way to ensure adequate intake.

Yes, vitamin D3 and K2 are highly synergistic. Vitamin D3 helps the body absorb calcium, while vitamin K2 activates proteins that guide this calcium to your bones and teeth, preventing its buildup in soft tissues like arteries. Combining them ensures proper calcium utilization.

Look for a supplement that contains MK-7 derived from natural fermentation (e.g., from natto or chickpeas). Ensure the label specifies a high purity of the active all-trans isomer (99%+). Reputable brands often provide third-party testing verification.

No, if you are taking blood-thinning medication like warfarin, you should not take vitamin K2 supplements without strict medical supervision. Vitamin K can counteract the medication's effects, potentially causing dangerous blood clots.

Vitamin K2 is generally considered safe and well-tolerated. No tolerable upper intake level has been established for vitamin K, as toxicity is not typically associated with high doses. However, the most significant risk is for individuals on specific anticoagulant medications.