Where is Vitamin K2 Available? A Guide to Food Sources and Supplements

December 27, 2025 •

4 min read

According to a 2017 analysis, menaquinones (vitamin K2) are synthesized by bacteria and are primarily found in fermented foods and animal products, making them less common in the average diet compared to Vitamin K1. Understanding where is vitamin K2 available is crucial for those seeking to support their bone and cardiovascular health through dietary choices or supplementation.

Quick Summary

This guide details the main dietary sources of vitamin K2, differentiating between the MK-4 and MK-7 forms found in animal and fermented foods, respectively. It also explores the reasons for low dietary intake in Western diets, discusses supplementation options, and highlights the synergistic relationship with Vitamin D3.

Key Points

Source Categories: Vitamin K2 is found in fermented foods (like natto) and animal products (such as grass-fed dairy, egg yolks, and liver), not typical green vegetables.
MK-4 vs. MK-7: K2 exists in different forms, with MK-4 from animal sources and MK-7 from fermented foods; MK-7 has a longer half-life, making it more bioavailable.
High-Concentration Foods: Natto is the richest natural source of K2 (MK-7), while goose liver pate is an exceptionally dense source of K2 from animal products.
Absorption and Availability: The K2 content in food is dependent on animal feeding practices and fermentation methods, and overall intake is low in typical Western diets.
Supplementation Considerations: Supplements, especially those with the MK-7 form, are a reliable option for consistent K2 intake, often combined with Vitamin D3 for synergistic benefits.
Health Benefits: Vitamin K2 plays a key role in directing calcium to the bones and teeth, supporting bone density and inhibiting arterial calcification.
Fat-Soluble Requirement: As a fat-soluble vitamin, K2 is absorbed best when consumed with dietary fat, found naturally in many of its sources like eggs and cheese.

The Two Forms of Vitamin K2: MK-4 and MK-7

Vitamin K2, also known as menaquinone, is a family of fat-soluble vitamins with different subtypes, primarily MK-4 and MK-7, which are found in different food types and have different half-lives in the body. MK-4 is a shorter-chain menaquinone found in animal products, while MK-7 is a longer-chain form predominantly found in fermented foods. This difference in structure impacts how effectively the body utilizes them. MK-7 has a longer half-life, meaning it stays in the bloodstream for a longer period, making it a more bioavailable and efficient option for maintaining consistent blood levels. In contrast, MK-4 is cleared from the body more quickly, requiring more frequent or higher intake to maintain its levels.

Dietary Sources of Vitamin K2

There are two main categories of food that provide vitamin K2: animal-based products and fermented foods. The quality and content of K2 in these foods are heavily dependent on how the animals were raised or how the food was fermented.

Fermented Foods (Rich in MK-7):

Natto: This traditional Japanese food made from fermented soybeans is by far the richest source of MK-7. It contains extremely high concentrations, though it has a unique taste and texture that may require some getting used to.
Sauerkraut: Fermented cabbage provides a modest amount of vitamin K2, along with beneficial probiotics that support gut health.
Kefir and Yogurt: These fermented dairy products contain varying amounts of MK-7, depending on the starter cultures and fermentation process. They offer a simple way to increase K2 intake.

Animal Products (Rich in MK-4):

Organ Meats: Liver, particularly goose and chicken liver, is one of the densest animal sources of K2.
Grass-Fed Dairy: Dairy products from grass-fed animals, such as certain hard cheeses (like Gouda and Edam) and butter, contain significant amounts of MK-4. The K2 content is higher in products from animals that graze on grass rich in Vitamin K1, which their bodies convert to K2.
Egg Yolks: The yolk of eggs from pasture-raised hens provides a good amount of vitamin K2, and the content is higher than in eggs from caged hens.
Meat: Goose liver pate is an exceptionally rich source, while other meats like bacon and chicken legs also contain K2.

Challenges in Achieving Optimal Vitamin K2 Intake

Despite the existence of food sources, several factors make it challenging for many people to get optimal levels of vitamin K2 through diet alone, especially in Western countries.

Modern Diet Shifts: The decline in consumption of fermented foods and organ meats, coupled with the prevalence of grain-fed animal products, has led to a lower average intake of K2.
Bioavailability Concerns: While vitamin K1 from plants can be converted to K2 in the gut, this process can be hindered by factors such as antibiotic use. Furthermore, absorption of K1 from plants can be poor compared to K2 from fermented foods.
Nutrient Density Trade-offs: Some of the richest K2 animal sources, like certain cheeses and butter, are also high in saturated fats and cholesterol, requiring moderate consumption.

Comparison of K2 Sources


Source Category	Primary K2 Subtype	Example Foods	Availability in Western Diet	Bioavailability
Fermented Foods	MK-7 (Long-chain)	Natto, Sauerkraut, Kefir	Low (Except some cheeses)	High (Longer half-life)
Animal Products	MK-4 (Short-chain)	Liver, Egg Yolks, Grass-fed Dairy	Moderate (Often lower quantity)	Lower (Shorter half-life)
Supplements	MK-7 or MK-4	Capsules, Softgels, Gummies	High	Can be very high, especially MK-7

The Role of Supplements

For many, supplements are a reliable way to ensure a consistent intake of vitamin K2. Supplements are available in both MK-4 and MK-7 forms, with MK-7 being a popular choice due to its longer half-life, which supports steady blood levels with less frequent dosing. Supplementation can be particularly beneficial for individuals with dietary restrictions or those who do not regularly consume foods rich in K2. Furthermore, vitamin K2 is often combined with Vitamin D3 in supplements, as these two vitamins work synergistically to support bone and cardiovascular health by directing calcium to the bones and away from arteries.

Conclusion

To find where vitamin K2 is available, it is necessary to look beyond standard green vegetables and explore both fermented and animal-based sources. For most, a combination of dietary adjustments and careful supplementation offers the best strategy for optimizing intake. While fermented soybeans (natto) provide the highest concentration of the bioavailable MK-7 form, sources like grass-fed dairy, egg yolks, and liver contribute the MK-4 form. Given that Western diets are often deficient in these foods, supplementation with a high-quality MK-7 product is a practical approach for ensuring adequate intake to support vital functions like bone mineralization and cardiovascular health. Always consult a healthcare provider, especially if you are taking blood thinners, before beginning a new supplement regimen.

Frequently Asked Questions

Vitamin K1 (phylloquinone) is mainly found in leafy green vegetables and is primarily involved in blood clotting. Vitamin K2 (menaquinone) is found in fermented foods and animal products, and its primary roles include supporting bone mineralization and preventing arterial calcification.

The highest concentration of vitamin K2, specifically the MK-7 subtype, is found in natto, a Japanese dish made from fermented soybeans. Among animal products, goose liver pate is exceptionally rich.

Yes, but primarily through fermented plant-based foods rather than vegetables. Plant-based sources of K2 include natto and sauerkraut. Non-fermented vegetables are rich in vitamin K1, which the body can partially convert to K2, but this process is inefficient.

Not all dairy products contain significant K2. High levels are more common in grass-fed dairy products, hard cheeses (like Gouda and Edam), and certain fermented dairy like kefir, as the K2 is synthesized by bacteria and concentrated in the fat.

The MK-7 form of vitamin K2 is generally considered superior for supplements due to its longer half-life, meaning it remains active in the body for a more extended period. This leads to more stable blood levels compared to the MK-4 form.

Vitamin K2 and Vitamin D3 work synergistically. While Vitamin D3 helps with calcium absorption, Vitamin K2 directs that calcium to where it is needed most, primarily the bones and teeth, while preventing its build-up in arteries and soft tissues.

Yes, the amount of vitamin K2 (MK-4) in animal products is highly dependent on the animal's diet. Grass-fed animals, which consume K1-rich grass, produce dairy and meat with higher K2 content compared to grain-fed animals.