Understanding Vitamin K2 and MK-7
Vitamin K is a fat-soluble vitamin essential for blood clotting and metabolic processes, particularly bone mineralization and soft tissue health. It primarily exists in two natural forms: Vitamin K1 (phylloquinone), found in plants, and Vitamin K2 (menaquinones), produced by bacteria. Menaquinones come in various subtypes, but MK-7 is particularly valued for its superior bioavailability and longer half-life, which allows it to reach extrahepatic tissues like bones and arteries more effectively.
The Premier Natural Source: Natto
If you want to know how to get MK-7 naturally, the undeniable top source is natto. This traditional Japanese dish consists of soybeans fermented with Bacillus subtilis bacteria and is exceptionally rich in MK-7. A single serving provides a potent dose that can significantly increase circulating MK-7 levels in the body.
- How to add natto to your diet: Natto has a distinct, strong taste and sticky texture that can be off-putting for some. To make it more palatable, mix it with soy sauce, mustard, chives, or rice. For those who can't tolerate the taste, a high-quality, natto-derived MK-7 supplement is a viable alternative.
Fermented Dairy and Cheese
Beyond natto, a variety of cheeses and other fermented dairy products are excellent sources of longer-chain menaquinones, including moderate amounts of MK-7, MK-8, and MK-9. The MK-7 content can vary significantly based on the type of cheese, bacterial strains used, and ripening time. Cheeses from grass-fed animals tend to have higher vitamin K content.
- Top cheese options: Aged Gouda, Brie, and some varieties of blue cheese are often cited as having higher MK-7 content compared to others.
- Cultured milk products: Kefir and certain yogurts, especially those with specific bacterial cultures, can also contribute to your MK-7 intake.
Other Animal Products
Certain animal products contain varying levels of vitamin K2, predominantly the MK-4 subtype, but often include some MK-7 as well. While not as concentrated as natto, these foods can still contribute to your overall vitamin K status.
- Chicken: Particularly chicken thigh and liver, contains notable amounts of both MK-4 and some MK-7.
- Grass-fed butter and eggs: Products from animals raised on pasture are more likely to have higher vitamin K2 levels in their fat.
- Beef: Organ meats like beef liver also provide a decent amount of MK-7, in addition to being rich in other nutrients.
Lifestyle and Gut Health Connection
The human gut microbiome produces menaquinones, but the bioavailability of these internally produced forms is often insufficient to meet the body's full needs, especially for extra-hepatic tissues. Optimizing gut health through a balanced diet can support this internal production. Incorporating a variety of fermented foods, including those high in MK-7, ensures a steady external supply that complements the body's own synthesis.
To maximize absorption of this fat-soluble vitamin, you should always consume MK-7 rich foods with a source of fat. For example, add a drizzle of olive oil to sauerkraut or enjoy aged cheese alongside nuts.
Comparison of Common MK-7 Sources
| Food Source | Primary MK-7 Content Level | Notable Benefit | Considerations |
|---|---|---|---|
| Natto | Exceptionally High | Highest concentration of MK-7 | Acquired taste, strong flavor |
| Aged Gouda | High | Widely available, good source for Western diets | MK levels vary; can be high in calories/saturated fat |
| Brie/Camembert | Moderate | Softer cheese option with good MK-7 levels | MK levels vary; can be high in calories/saturated fat |
| Chicken (thigh/liver) | Moderate | Good source of both MK-4 and MK-7 | Must be cooked correctly; organ meats are nutrient-dense |
| Sauerkraut | Moderate-Low | Vegan-friendly source; good for gut health | Lower MK-7 content than natto; can be high in sodium |
Conclusion
While a variety of foods contain vitamin K2, the most concentrated and bioavailable form of menaquinone-7 (MK-7) is found in natto. For those with palatal or dietary restrictions, supplementing with MK-7 can be an effective way to meet nutritional needs. For everyone, integrating a diverse range of fermented foods and high-quality animal products, particularly from grass-fed sources, remains the best natural strategy for optimizing MK-7 intake. A balanced diet rich in these natural sources can play a significant role in promoting long-term bone density and cardiovascular health. For a deeper scientific dive into the biological pathways affected by MK-7, consult peer-reviewed research.
