Natto: The Unquestionable Vitamin K Champion
When asking "Which food is highest in vitamin K?", the definitive answer for the K2 variant is natto. Natto is a traditional Japanese dish made from fermented soybeans and is an extraordinarily potent source of menaquinones (vitamin K2). In fact, it is considered one of the most vitamin K2-rich foods available, containing hundreds of micrograms of vitamin K2 in a single serving. While its unique texture and strong flavor can be an acquired taste, its nutritional profile is unparalleled for those seeking to maximize their K2 intake.
The K1 Powerhouses: Dark Leafy Greens
For phylloquinone (vitamin K1), the highest concentrations are found in dark, leafy green vegetables. These vibrant foods are common staples in many diets and offer an excellent way to boost vitamin K levels easily. While natto is the clear winner for overall vitamin K, these vegetables are far more accessible to most people and provide a significant dietary contribution.
Top Sources of Vitamin K1 (per 100g)
- Raw Swiss Chard: With up to 830 mcg, raw Swiss chard is a phenomenal source.
- Raw Dandelion Greens: Offering around 778 mcg, these greens are highly nutrient-dense.
- Cooked Kale: A 100g serving of cooked kale provides over 400 mcg.
- Cooked Mustard Greens: These pack a powerful punch with over 590 mcg.
- Cooked Collard Greens: Rich in K1, cooked collard greens contain over 620 mcg per 100g.
- Raw Spinach: A 100g portion of raw spinach can deliver around 483 mcg.
Comparing Vitamin K1 and K2 Sources
Understanding the difference between the two main forms of vitamin K is essential for a balanced diet. K1, primarily from plants, is vital for blood clotting. K2, from fermented and animal products, has shown benefits for bone health and cardiovascular function by preventing arterial calcification.
| Food Source | Primary Vitamin K Type | Notes | Amount (per 100g) | Daily Value (DV) % (approx.) |
|---|---|---|---|---|
| Natto | K2 (MK-7) | Fermented soybeans with a distinct taste. | 939-1,062 mcg | >700% |
| Goose Liver Pate | K2 | Rich, fatty animal product. | 369 mcg | ~308% |
| Swiss Chard (Raw) | K1 | Leafy green vegetable. | 830 mcg | ~692% |
| Blue Cheese | K2 | Fermented dairy product. | 440 mcg | ~367% |
| Beef Liver | K2 | Organ meat. | 106 mcg | ~88% |
| Cooked Kale | K1 | Versatile and common leafy green. | 418.5 mcg | ~348% |
| Cooked Spinach | K1 | Common leafy green, cooking can increase levels. | 540.7 mcg | ~451% |
The Importance of Vitamin K in Your Diet
Beyond simply identifying the highest source, understanding why vitamin K is crucial highlights the importance of including these foods in your diet. Vitamin K is a fat-soluble vitamin that enables your body to produce proteins vital for blood clotting. Without it, wounds would not stop bleeding properly. Furthermore, vitamin K is essential for bone metabolism, helping to ensure calcium is properly utilized and preventing bone weakening and conditions like osteoporosis. Emerging research also links adequate vitamin K intake to better cardiovascular health by reducing arterial calcification.
Other Notable Vitamin K Sources
While natto and leafy greens are the highest, other foods contribute to your overall vitamin K intake, offering variety in your diet.
- Broccoli: Both raw and cooked broccoli contain substantial amounts of vitamin K1.
- Brussels Sprouts: A small serving of cooked Brussels sprouts provides a significant portion of the recommended daily intake.
- Soybean Oil: This common cooking oil is another good source of vitamin K1.
- Cheeses: Certain fermented and aged cheeses like Gouda and Blue cheese are decent sources of vitamin K2.
- Eggs and Meat: The vitamin K2 content in eggs and meat, particularly organ meats like liver, varies based on the animal's diet but can still contribute to your intake.
Factors Affecting Vitamin K Absorption
Since vitamin K is a fat-soluble vitamin, consuming it with a source of fat can enhance absorption. This is why adding a healthy oil-based dressing to a kale salad or cooking greens with a bit of butter can be beneficial. Gut health also plays a role, as the beneficial bacteria in your intestines can produce some vitamin K2. However, a balanced diet rich in varied vitamin K sources is the most reliable way to meet your needs. For vegetarians and vegans, natto is a unique K2 source, but the vast majority of their intake will come from K1 in plants.
Conclusion
While a variety of foods contain vitamin K, fermented soybeans (natto) provide the highest concentration of the K2 variant. For the more common K1 type, dark leafy greens such as raw Swiss chard and cooked kale are unmatched in their content. For most people, a well-balanced diet that includes a mix of these sources ensures adequate intake of both vitamin K1 and K2. Understanding these top contenders and incorporating them into your meals is an effective strategy for supporting blood clotting, maintaining strong bones, and promoting overall health.
Learn more about the differences between Vitamin K1 and K2 on Healthline.com
