Natto: The Undisputed King of Vitamin K2
While many foods contain vitamin K2, the Japanese fermented soybean dish known as natto consistently tops all lists as the single richest source. The fermentation process, which uses the Bacillus subtilis bacteria, produces a high concentration of the highly bioavailable menaquinone-7 (MK-7) form of vitamin K2. A single 100-gram serving can provide over 1,000 micrograms (mcg) of K2, which is well above the recommended daily intake for most people. Despite its superior nutritional profile, natto's strong, pungent flavor and slimy texture can be an acquired taste for many Western palates. For those who can tolerate or come to enjoy it, a small serving of natto is an incredibly effective way to significantly increase vitamin K2 intake.
Other High-Ranking Foods for Vitamin K2
For those who aren't keen on natto, a variety of other fermented and animal-based foods offer substantial amounts of vitamin K2. The specific type of menaquinone (MK-4, MK-7, MK-8, MK-9) and its concentration can vary depending on the food.
Hard and soft cheeses
Certain cheeses are excellent sources of K2, particularly the longer-chain menaquinones like MK-8 and MK-9. Aged Gouda, for example, is recognized for its high K2 content, along with Swiss cheeses like Emmentaler and Raclette. The K2 content in cheese tends to increase with the aging process. Soft fermented cheeses like Brie also contain good amounts.
Organ and animal meats
Animal products are the primary source of the MK-4 form of vitamin K2. Organ meats are particularly potent. Goose liver pate stands out with an exceptionally high concentration of MK-4, while beef and chicken liver are also very good sources. Regular chicken meat, especially the dark meat from the leg and thigh, contains respectable amounts of K2.
Pastured eggs and butter
The diet of the animal significantly impacts the vitamin K2 content of its products. Eggs from chickens raised on pasture and grass-fed butter are richer in K2 (MK-4) than those from conventionally-raised, grain-fed animals. Egg yolks, in particular, are where the vitamin K2 is concentrated.
Comparing Top Vitamin K2 Sources
This table outlines the approximate vitamin K2 content for the most potent dietary sources. It's important to note that values can vary depending on the specific product, preparation, and analysis method.
| Food Source | Approximate K2 Content (per 100g) | Primary K2 Form | Notes |
|---|---|---|---|
| Natto | 600–1,000+ mcg | MK-7 | Highest concentration, strong taste and texture. |
| Goose Liver Pate | 369 mcg | MK-4 | Exceptionally high, but less common and can be high in calories. |
| Hard Cheeses (e.g., Gouda, Emmentaler) | Up to 76 mcg | MK-8, MK-9 | Content increases with aging; varies by cheese type. |
| Soft Cheeses (e.g., Brie) | Up to 57 mcg | MK-8, MK-9 | Varies by cheese type and production. |
| Pastured Egg Yolks | 15–30 mcg per yolk | MK-4 | Content depends heavily on chicken's diet. |
| Chicken Liver | Up to 12.6 mcg | MK-4 | Good source, but often consumed in smaller quantities. |
How to incorporate more vitamin K2
To maximize your intake, a varied diet is key. Here are some strategies:
- Embrace fermented foods: For the most potent source, try incorporating small portions of natto into your meals. For a milder option, consider high-quality sauerkraut, which also contains K2, though in much lower quantities.
- Choose aged cheeses: Opt for aged Gouda, Brie, or Swiss cheese varieties. The ripening process enhances the K2 content.
- Select grass-fed and pastured products: When possible, choose dairy, eggs, and meat from animals raised on pasture. Their diets, rich in vitamin K1 from grass, lead to higher K2 levels in their products.
- Include organ meats: Beef or chicken liver can be included in your diet in moderation for a boost of K2 (MK-4).
- Pair with fats: Since vitamin K is fat-soluble, consuming K2-rich foods with healthy fats like butter or olive oil can enhance absorption.
Conclusion: Natto leads the way, but options abound
Without a doubt, natto is the most concentrated single food source of vitamin K2. However, its unappealing taste to many means it's not a practical option for everyone. Fortunately, for those seeking to increase their vitamin K2, a diverse array of other foods are available, including specific fermented cheeses and quality animal products like goose liver pate, pastured egg yolks, and grass-fed butter. By incorporating a variety of these different sources, individuals can ensure they are getting a spectrum of menaquinones (MK-4, MK-7, etc.) and reaping the diverse health benefits of this crucial nutrient, which include supporting bone health and protecting cardiovascular function. It is also important to remember that dietary guidelines based on older research often focus on vitamin K1 from leafy greens, and the best dietary approach involves a balance of both K1 and K2.
Key takeaways
- Natto is highest: Natto, a fermented soybean dish from Japan, is the richest food source of vitamin K2, specifically the MK-7 subtype.
- Cheeses are excellent: Hard and soft cheeses, particularly aged Gouda, Emmentaler, and Brie, offer significant amounts of vitamin K2.
- Organ meats are potent: Goose liver pate, beef liver, and chicken liver are powerful sources of vitamin K2, predominantly the MK-4 form.
- Animal diet matters: The vitamin K2 content in eggs and butter is higher when sourced from pasture-raised, grass-fed animals.
- Pair with fat for absorption: Vitamin K2 is fat-soluble, so consume these foods with a healthy fat to enhance its absorption by the body.
- Different forms exist: Foods offer different types of vitamin K2 (MK-4, MK-7, etc.), so a variety of sources provides a broader spectrum of menaquinones.
FAQs
Q: What is the primary function of vitamin K2? A: Vitamin K2's main function is to activate proteins that help direct calcium to the bones and teeth while preventing it from accumulating in soft tissues like arteries and kidneys, supporting bone and cardiovascular health.
Q: How does vitamin K1 differ from K2? A: Vitamin K1 (phylloquinone) is found primarily in leafy green vegetables and is vital for blood clotting, while vitamin K2 (menaquinone) is found in animal products and fermented foods and is most crucial for calcium metabolism and bone health.
Q: Is it possible to get enough vitamin K2 from fermented vegetables besides natto? A: While some fermented vegetables like sauerkraut contain vitamin K2, the concentration is much lower compared to natto. Natto is in a class of its own for K2 content among fermented plant foods.
Q: Why do pastured animal products have more vitamin K2? A: When animals like chickens and cows graze on grass rich in vitamin K1, their gut bacteria convert it into vitamin K2, which then accumulates in their fat, eggs, and milk.
Q: Should people on blood-thinning medication be concerned about vitamin K2? A: Yes, anyone taking blood-thinning medication like warfarin should consult their doctor before increasing their intake of any vitamin K, including K2, as it can interfere with the drug's effectiveness.
Q: Do all types of cheese have high vitamin K2? A: No, the K2 content varies significantly between cheeses. Aged and hard cheeses like Gouda and Emmentaler typically have higher levels than fresh or softer cheeses.
Q: Can the body convert vitamin K1 to K2? A: Yes, the body's gut bacteria can convert some vitamin K1 into K2, but dietary intake of K2 is still considered the most reliable way to obtain this specific form.
Q: Do supplements offer a reliable source of vitamin K2? A: Yes, vitamin K2 supplements, particularly those containing MK-7, are an effective way to ensure adequate intake, especially for those who don't consume K2-rich foods regularly.
Citations
[ { "title": "Top Foods High in Vitamin K2: The Ultimate Guide", "url": "https://athenslab.gr/en/blog/nutrition/top-foods-high-in-vitamin-k2-the-ultimate-guide" }, { "title": "Top Foods High in Vitamin K2 - WebMD", "url": "https://www.webmd.com/diet/foods-high-in-vitamin-k2" }, { "title": "Vitamin K2 - Wikipedia", "url": "https://en.wikipedia.org/wiki/Vitamin_K2" }, { "title": "Richest Food Sources of Vitamin K2 - Dr Steven Lin", "url": "https://www.drstevenlin.com/what-are-the-richest-food-sources-of-vitamin-k2/" }, { "title": "How to Get Vitamin K2 Into Your Diet & When to Supplement", "url": "https://www.ombecenter.com/blog/how-to-get-vitamin-k2-into-your-diet" } ] }
