The Richest Natural Sources of MK-7
The primary and most potent sources of menaquinone-7 (MK-7) are fermented foods, which harness bacteria to create this powerful nutrient. The fermentation process is key, as the bacteria are responsible for synthesizing the long-chain menaquinones like MK-7.
Natto: The Unrivaled Superfood Source
By far the richest source of MK-7 is natto, a traditional Japanese dish made from fermented soybeans. The fermentation process, which uses the bacterium Bacillus subtilis, results in an exceptionally high concentration of MK-7. A standard 3.5-ounce serving of natto can provide a massive amount of MK-7, far exceeding other dietary sources.
Cheeses and Fermented Dairy
Beyond natto, certain fermented dairy products are also notable sources of MK-7, though the levels can vary significantly depending on the bacterial strains used and the aging process. Hard and soft cheeses, in particular, contain valuable amounts of long-chain menaquinones.
Some cheeses with moderate to high MK-7 content include:
- Gouda: A prominent source of menaquinones.
- Brie and Camembert: Certain soft, fermented cheeses contain notable amounts.
- Edam: Contains a good level of MK-7.
Other Fermented Foods
While not as high in MK-7 as natto or specific cheeses, other fermented products can contribute to your intake:
- Sauerkraut: Fermented cabbage contains small but meaningful amounts of MK-7.
- Kefir: Some research shows that certain bacterial cultures in kefir, especially those using traditional grains, can produce MK-7.
- Fermented Chickpeas and Lentils: Emerging research indicates that fermenting other legumes like chickpeas and lentils with Bacillus subtilis can produce high levels of MK-7.
MK-7 vs. Other Forms of Vitamin K2
Vitamin K2 encompasses various subtypes, known as menaquinones (MK-n). The most important forms are MK-4 and MK-7, which differ significantly in their sources and physiological impact.
| Feature | MK-7 | MK-4 |
|---|---|---|
| Source | Produced by bacterial fermentation. Found in natto, cheeses, and sauerkraut. | Produced by animal tissues, often by converting Vitamin K1 from the animal's diet. Found in animal fats, eggs, and liver. |
| Half-Life | Long. Remains in the bloodstream for approximately 72 hours, leading to better accumulation. | Short. Rapidly disappears from circulation after intake. |
| Bioavailability | High. Shows superior bioavailability and efficacy for extrahepatic tissues like bones and arteries. | Lower systemic bioavailability compared to MK-7, requiring higher doses for similar effects. |
| Primary Role | Activates proteins crucial for both bone and cardiovascular health. | Involved in bone health, but MK-7 is more effective for extrahepatic activity. |
| Origin | Found naturally in specific fermented foods. | Found naturally in animal products via conversion. |
Vegan Sources of MK-7
For those following a vegan diet, obtaining MK-7 can be challenging as many traditional sources are dairy-based. However, excellent plant-based options exist:
- Natto: As the king of MK-7, natto is a fully plant-based food and an ideal vegan choice.
- Supplements: Many MK-7 supplements are derived from fermented sources like chickpeas or soy and are certified vegan. It's important to check the product label for confirmation.
- Sauerkraut: A small amount of MK-7 is present in fermented cabbage, making it a viable, though less concentrated, vegan option.
- Other Fermented Legumes: Some fermented products using lentils or chickpeas can also provide MK-7.
Ensuring Optimal Intake of MK-7
Since MK-7 is a fat-soluble vitamin, its absorption is significantly enhanced when consumed with a source of fat. This is naturally done when eating full-fat cheeses, but should be considered when consuming low-fat fermented foods or supplements. For instance, pairing sauerkraut with a drizzle of oil or taking a supplement with an MCT oil base can improve absorption.
Dietary intake of MK-7 is highly variable globally, with some populations consuming significant amounts and others very little. If your diet lacks regular consumption of natto or certain aged cheeses, incorporating a high-quality MK-7 supplement can be a reliable way to ensure adequate intake. When choosing a supplement, look for those containing MK-7 from natural, fermented sources like chickpeas for better bioavailability. For more on the different forms and effects of vitamin K, the Linus Pauling Institute is a helpful resource (Linus Pauling Institute - Vitamin K).
Conclusion
To summarize, where is MK-7 found? The most concentrated source is the Japanese fermented soybean dish, natto. It is also available in smaller amounts in certain aged and fermented cheeses and other fermented vegetables like sauerkraut. For those who cannot or choose not to consume these foods, high-quality dietary supplements derived from fermented chickpeas or soy are a readily available and effective alternative. Prioritizing MK-7 in your diet is a powerful step toward supporting long-term bone and cardiovascular health.
