What are the sources of Menaquinone 7?

December 18, 2025 •

3 min read

An impressive 100g serving of natto, a traditional Japanese fermented soybean dish, can contain over 1,000 micrograms of Menaquinone 7 (MK-7). This makes it by far the richest known food source of this important nutrient, a fact that highlights the key role of bacterial fermentation in producing MK-7.

Quick Summary

Menaquinone 7 (MK-7) is primarily derived from bacterial fermentation, with natto being the most concentrated dietary source. Lesser amounts are found in other fermented foods and some animal products, but supplements also provide a reliable intake of this form of Vitamin K2.

Key Points

Natto is King: The Japanese fermented soybean dish, natto, is the richest food source of MK-7, with some servings containing over 1,000 mcg.
Bacteria are the Producers: Menaquinone 7 is primarily synthesized by bacteria during the fermentation of foods like soybeans, cheeses, and sauerkraut.
Supplements are a Reliable Alternative: For consistent intake, MK-7 dietary supplements offer high bioavailability and a longer-lasting effect than other forms of vitamin K2, such as MK-4.
Fermented Dairy Offers Some MK-7: Aged cheeses like Gouda and some fermented products like kefir can provide moderate levels of MK-7, though less than natto.
Gut Bacteria are Not Enough: While your gut flora produces menaquinones, the absorption from this source is poor and does not meet the body's requirements.
MK-7 vs. MK-4 Sources: MK-7 comes from bacterial fermentation (natto, cheese), while the more transient MK-4 is found in animal products like liver, egg yolks, and meat.
Requires Fat for Absorption: For optimal absorption, it is important to consume MK-7 sources alongside a meal containing some fat, as it is a fat-soluble vitamin.

Fermented Foods: The Richest Sources of MK-7

The primary sources of Menaquinone 7 are fermented foods, in which specific bacteria synthesize the compound. The availability of MK-7 in these foods can depend on several factors, including the type of bacteria used and the duration of the fermentation process. While many fermented items contain some level of menaquinones, a few stand out as top-tier sources of MK-7.

Natto

For anyone seeking a concentrated dietary source of MK-7, natto is the undisputed champion. This traditional Japanese food consists of soybeans fermented with the bacteria Bacillus subtilis natto. Studies show that even moderate, regular consumption of natto can significantly increase serum MK-7 levels, which is associated with improved bone health outcomes. For many, the strong, distinct flavor and sticky texture of natto are an acquired taste, but its nutritional value is undeniable.

Fermented Dairy Products

While not as rich in MK-7 as natto, certain fermented dairy products are also valuable sources. Cheeses, especially aged and hard varieties like Gouda and some soft cheeses like Brie and Camembert, contain menaquinones synthesized by the bacterial cultures used in their production. Kefir, a fermented milk drink, has also been shown to contain notable levels of MK-7, with content increasing throughout the fermentation period. The specific bacterial strains utilized, and the amount of fat in the dairy product, can influence the final MK-7 concentration.

Sauerkraut

This fermented cabbage, popular in Western diets, contains smaller but still significant amounts of menaquinones, including MK-7. The bacterial fermentation process is responsible for the production, though levels are generally much lower than in natto.

Menaquinone-7 from Supplements

For those who cannot or prefer not to consume fermented foods, dietary supplements offer a reliable way to get MK-7. Both synthetic and natural MK-7 supplements are available, often sourced from natto extract or produced through microbial fermentation. Studies comparing MK-7 and MK-4 bioavailability at nutritional doses show that MK-7 is absorbed much more effectively and provides longer-lasting serum levels. This sustained availability makes MK-7 a preferred choice for supplemental vitamin K2, particularly for supporting long-term bone and cardiovascular health.

Less Reliable Sources: Gut Bacteria and Animal Products

Intestinal Flora

Your gut microbiome does produce menaquinones, including MK-7, but relying on this for your daily requirement is not effective. The MK-7 synthesized by bacteria in the colon is not well-absorbed in the distal part of the digestive tract where it is produced. Consequently, the contribution of gut flora-produced MK-7 to the body's overall vitamin K status is considered minimal.

Animal-Derived MK-7

While many animal products contain vitamin K2, they are primarily known for providing the MK-4 form, not MK-7. Some cured or fermented meats like salami and certain types of chicken can contain trace amounts of MK-7, but are not considered significant sources. Grass-fed butter, eggs, and liver are rich in MK-4, but not the long-chain MK-7 produced by bacteria.

Comparison of Major MK-7 Sources


Source Category	Specific Food Examples	Primary MK-7 Synthesis Method	Typical MK-7 Concentration	Bioavailability/Reliability
Fermented Soy	Natto	Fermentation by Bacillus subtilis natto	Extremely High (up to 1,000+ mcg per 100g)	Excellent, most reliable food source
Fermented Dairy	Aged Cheeses (Gouda, Camembert), Kefir	Bacterial fermentation during aging	Moderate, varies significantly by product	Good, contributes to overall intake
Fermented Vegetables	Sauerkraut	Bacterial fermentation	Low to Moderate	Lower, but still a source
Supplements	Capsules, tablets	Microbial production, synthesis	Consistent, controlled dose	Excellent, highly reliable source with superior half-life
Gut Bacteria	None	Gut microflora synthesis	Insignificant dietary contribution	Poorly absorbed, unreliable for sufficiency

Conclusion

Menaquinone 7 is predominantly a byproduct of bacterial activity, with fermented foods offering the most significant natural dietary concentrations. Natto, in particular, stands out as the richest and most reliable food source, while aged cheeses and other fermented products also contribute to overall intake. For consistent and concentrated amounts, dietary supplements containing MK-7 offer high bioavailability and sustained serum levels, making them an excellent alternative for those who cannot get enough through diet alone. While the body’s own gut bacteria produce menaquinones, absorption from this source is insufficient for adequate vitamin K status. Ultimately, a conscious effort toward consuming fermented foods or opting for a quality supplement is the most effective way to ensure sufficient Menaquinone 7 intake for optimal health benefits.

Visit the NIH website for comprehensive information on Vitamin K and other nutrients.

Frequently Asked Questions

The fermented Japanese soybean product known as natto is the richest food source of Menaquinone 7 (MK-7), with significantly higher concentrations than any other known food.

Yes, some cheeses, particularly aged and hard varieties like Gouda, can contain notable amounts of menaquinones, including MK-7. The concentration varies depending on the type of cheese and the bacterial cultures used in its production.

No, MK-7 and MK-4 are both forms of Vitamin K2 but have different sources and bioavailability. MK-7 is primarily from bacteria and has a long half-life, while MK-4 comes from animal products and has a much shorter half-life.

No, research suggests that the menaquinones produced by your gut bacteria are not well-absorbed in the area where they are synthesized and contribute only minimally to your overall vitamin K status.

Bacterial fermentation is the key process for creating Menaquinone 7. Specific bacteria, such as Bacillus subtilis natto, synthesize MK-7 as a metabolic byproduct, which is then present in the fermented food.

Yes, natto is a high-concentration vegan source of MK-7. Sauerkraut also contains smaller amounts. Certain MK-7 supplements are also derived from bacterial fermentation and are suitable for vegans.

MK-7's long half-life means it remains available in your bloodstream for a longer period compared to other forms like MK-4. This provides more consistent support for activating proteins crucial for bone and cardiovascular health.