What is a good source of vitamin K2?

January 7, 2026 •

3 min read

Natto, a traditional Japanese fermented soybean dish, is recognized as the richest known food source of vitamin K2. This fat-soluble vitamin, also known as menaquinone, is crucial for both cardiovascular and bone health, but it is not as abundant in the modern Western diet as its counterpart, vitamin K1. Understanding what is a good source of vitamin K2 can help you make informed dietary choices to optimize your intake.

Quick Summary

Several food sources provide vitamin K2, primarily fermented foods and animal products, with natto being the most concentrated source of the MK-7 subtype. Animal products from grass-fed sources typically provide the MK-4 subtype. Both forms are vital for calcium metabolism, inhibiting arterial calcification, and supporting bone density.

Key Points

Natto is the richest source: A traditional Japanese fermented soybean dish, natto, contains extremely high levels of the highly bioavailable MK-7 form of vitamin K2.
Animal and fermented foods are key: The primary dietary sources of vitamin K2 are fermented foods (for MK-7) and animal products, particularly those from grass-fed animals (for MK-4).
Supports bone and heart health: Vitamin K2 is vital for activating proteins that direct calcium to bones and away from arteries, thus supporting strong bones and flexible blood vessels.
MK-7 has a longer half-life: The MK-7 form, commonly from fermented foods, stays in the bloodstream longer than MK-4 from animal products, making it more effective at lower doses for extra-hepatic tissues.
Strategize your intake: To increase vitamin K2, consider incorporating natto, aged cheeses, grass-fed butter, egg yolks, and organ meats into your diet, ideally alongside healthy fats to aid absorption.
Consult a professional on supplements: If considering supplementation, especially MK-7, talk to a healthcare provider. This is particularly important for individuals on blood-thinning medications.

Top Food Sources of Vitamin K2

While vitamin K1 is primarily found in leafy green vegetables, vitamin K2 comes mainly from fermented foods and animal products. The two main types of K2 are MK-4 and MK-7, found in different sources.

Fermented Foods: The MK-7 Connection

Fermented foods, particularly those using Bacillus subtilis natto bacteria, are excellent sources of the MK-7 form of vitamin K2. Natto is the richest known source of vitamin K2, providing a high concentration of MK-7. Aged and hard cheeses like Gouda and Brie contain longer-chain menaquinones such as MK-8 and MK-9. The K2 content varies by type and aging. Sauerkraut offers vitamin K2, although typically less than natto. Kefir is a fermented dairy drink that can provide K2 and probiotics.

Animal Products: The MK-4 Connection

Animal products are a primary source of the MK-4 form of vitamin K2. The amount of K2 in these foods is higher when the animals are grass-fed, as they convert K1 from plants into K2. Organ meats, such as goose and chicken liver, are particularly rich in MK-4. Egg yolks from pastured or grass-fed chickens are good sources of MK-4. Grass-fed dairy products like butter contain notable levels of MK-4. Fatty meats from pastured animals, such as chicken thighs with skin, pork, and beef, contain MK-4.

MK-4 vs. MK-7: Key Differences and Benefits

MK-4 and MK-7 have different properties and effects in the body, although both are important for activating proteins related to bone and heart health.


Feature	MK-4 (Menaquinone-4)	MK-7 (Menaquinone-7)
Source	Animal products	Fermented foods, gut bacteria
Half-Life	Short	Long
Bioavailability	Quickly absorbed, requires frequent intake	High, less frequent dosing possible
Distribution	Primarily liver, brain	Bones, arteries, other tissues
Research Focus	Used as osteoporosis treatment in Japan	Focus of cardiovascular and bone health studies

The Role of Vitamin K2 in the Body

Beyond blood clotting, vitamin K2 activates proteins like matrix Gla protein (MGP) and osteocalcin. MGP prevents calcium buildup in soft tissues like arteries, while osteocalcin helps integrate calcium into bones. This is crucial for preventing arterial calcification, a risk factor for heart disease, and supporting bone density. A lack of K2 can lead to inactive proteins and improper calcium distribution.

Considerations for Sourcing and Intake

Due to lower K2 levels in many diets, supplements are an option. MK-7 is often preferred for supplements due to its longer half-life and better bioavailability. Consult a healthcare professional before taking supplements, especially if on blood thinners. Increasing dietary intake means focusing on sources like natto, grass-fed animal products, and fermented cheeses. Since K2 is fat-soluble, consuming these foods with healthy fats enhances absorption.

Conclusion

Good sources of vitamin K2 include natto, aged cheeses, grass-fed dairy, egg yolks, and organ meats. Vitamin K2 is essential for directing calcium for strong bones and flexible arteries, yet it's often deficient in modern diets. While there's no official recommended daily allowance, incorporating K2-rich foods and considering supplementation (preferably MK-7 after consulting a doctor) can help maintain adequate levels for health. Consuming K2 alongside vitamins A and D supports various bodily processes. For more information, visit the {Link: National Institutes of Health website https://consensus.app/search/top-foods-high-in-vitamin-k2-write-as-an-article-w/oyIwqLiwSJOVeJBYNKEAUg/} on vitamin K.

Frequently Asked Questions

The single best food source for vitamin K2 is natto, a traditional Japanese food made from fermented soybeans, which contains exceptionally high concentrations of the MK-7 subtype.

MK-4 is a short-chain form found in animal products and has a short half-life, meaning it is quickly cleared from the body. MK-7 is a long-chain form from fermented foods with a longer half-life, allowing it to accumulate and act more effectively in tissues outside the liver.

Dairy products can be a good source of vitamin K2, particularly those from grass-fed animals. Aged and hard cheeses like Gouda and Brie are especially good sources of menaquinones.

Most modern Western diets are low in vitamin K2, especially compared to the high-intake populations seen in studies. Many people may not consume enough from food alone, particularly if they limit dairy or organ meats.

While leafy green vegetables are high in vitamin K1, they are not a significant source of vitamin K2. Fermented vegetables, like sauerkraut, do contain some K2 due to bacterial activity, but typically in lower amounts than natto.

Vitamin K2 activates two key proteins: osteocalcin, which binds calcium to your bones, and matrix Gla protein (MGP), which prevents calcium from depositing in soft tissues like arteries and blood vessels.

A deficiency in vitamin K2 can lead to non-activated proteins that regulate calcium, increasing the risk of both poor bone mineralization (leading to conditions like osteoporosis) and the calcification of blood vessels.