What has the highest source of vitamin K: A deep dive into top contenders
While many foods contain some amount of this vital nutrient, a select few stand out as being exceptionally rich. The highest source of vitamin K can differ depending on whether you are looking for vitamin K1 or vitamin K2, the two primary forms of the vitamin found in food.
Natto: The undisputed champion of Vitamin K2
For those seeking the absolute highest source of vitamin K, the answer is natto. This traditional Japanese food, made from fermented soybeans, is packed with vitamin K2 (menaquinone). A single 3-ounce serving of natto contains an incredible 850 micrograms (mcg) of vitamin K2, which is more than seven times the daily value. The fermentation process is responsible for producing these high concentrations of K2, particularly the menaquinone-7 (MK-7) subtype, which is known for its high bioavailability. The powerful effect of natto on bone health, particularly in postmenopausal women, has been highlighted in studies.
Leafy greens: The leading sources of Vitamin K1
When it comes to vitamin K1 (phylloquinone), dark, leafy green vegetables are the undisputed champions. Several greens compete for the top spot, with cooked varieties often concentrating the vitamin better than raw ones due to water loss during the cooking process.
- Boiled collard greens: A half-cup serving provides 530 mcg, delivering a massive 442% of the daily value.
- Boiled turnip greens: The greens of the turnip are another excellent source, offering 426 mcg in a half-cup serving after being boiled from frozen.
- Kale (cooked): This superfood lives up to its reputation, with a half-cup of cooked kale providing 247 mcg.
- Raw spinach: Not far behind, a single raw cup contains 145 mcg, which can be easily added to salads or smoothies.
Other notable sources of vitamin K
While natto and leafy greens are the highest sources, a variety of other foods can contribute significantly to your daily intake. These include other cruciferous vegetables, fruits, and animal products.
A list of other high vitamin K foods:
- Cruciferous vegetables: Brussels sprouts and broccoli both contain substantial amounts of vitamin K1. A cup of boiled Brussels sprouts offers 156 mcg, while a half-cup of boiled broccoli contains 110 mcg.
- Soybean oil and canola oil: These vegetable oils are rich in vitamin K1. Just one tablespoon of soybean oil can provide a significant boost.
- Herbs: Dried herbs like thyme and parsley are surprisingly high in vitamin K. Thyme, for example, offers 46 mcg per tablespoon.
- Animal products: For vitamin K2, look to liver, eggs, and cheese. The content can vary, with hard cheeses and fatty meats generally being better sources than lean ones.
Comparison Table: Vitamin K Powerhouses
| Food Source | Vitamin K Type | Serving Size | Micrograms (mcg) | Percent Daily Value | Reference |
|---|---|---|---|---|---|
| Natto | K2 (MK-7) | 3 oz | 850 | 708% | |
| Collard Greens (boiled) | K1 | 1/2 cup | 530 | 442% | |
| Turnip Greens (boiled) | K1 | 1/2 cup | 426 | 355% | |
| Swiss Chard (raw) | K1 | 1 leaf | 398 | 332% | |
| Kale (cooked) | K1 | 1/2 cup | 247 | 205% | |
| Spinach (raw) | K1 | 1 cup | 145 | 121% | |
| Brussels Sprouts (boiled) | K1 | 1 cup | 156 | 130% | |
| Soybean Oil | K1 | 1 tbsp | 25 | 21% | |
| Dried Thyme | K1 | 1 tbsp | 46 | 38% |
Health benefits of consuming a high vitamin K diet
Regularly consuming foods high in vitamin K offers several health benefits. It is a key player in ensuring proper blood clotting and is also vital for bone metabolism. Adequate intake may reduce the risk of bone fractures and osteoporosis by helping to produce proteins that regulate bone mineralization. Moreover, some studies suggest that vitamin K, particularly K2, plays a role in cardiovascular health by preventing vascular calcification, a risk factor for heart disease.
Maximizing absorption of vitamin K
As a fat-soluble vitamin, vitamin K is best absorbed when consumed with a source of fat. This is especially true for vitamin K1 from leafy greens. Adding a drizzle of olive oil to a kale salad or cooking greens with a bit of butter can significantly increase the amount of vitamin K your body absorbs. Fermented foods like natto, which naturally contain healthy fats, also promote good absorption.
Conclusion
While a variety of foods contain vitamin K, natto stands out as the single highest source, particularly for the K2 variant. For those focusing on vitamin K1, dark leafy greens like collards, turnip greens, kale, and spinach are the most potent sources. Incorporating a diverse range of these vitamin K-rich foods, including both plant-based options and fermented items, is the best strategy to ensure adequate intake and support essential bodily functions like blood clotting and bone health. Remember to pair these foods with a healthy fat to maximize absorption. The wealth of benefits from this often-overlooked nutrient makes it a crucial component of any balanced diet.
Frequently Asked Questions
What is the richest food source of vitamin K?
The richest single food source of vitamin K is natto, a Japanese dish made from fermented soybeans, which is exceptionally high in vitamin K2.
Is it better to get vitamin K from K1 or K2 sources?
For optimal health, it is best to consume a variety of foods that provide both vitamin K1 (from leafy greens) and vitamin K2 (from fermented foods and animal products), as they may have slightly different functions in the body.
What are some other high sources of vitamin K besides natto and leafy greens?
Other excellent sources include soybean oil, Brussels sprouts, broccoli, certain cheeses, and organ meats like liver.
Can cooking affect the vitamin K content of vegetables?
Cooking, particularly boiling, can cause water-soluble nutrients to leach out, but since vitamin K is fat-soluble, it remains stable. In some cases, cooking can even increase the concentration of vitamin K by reducing the vegetable's water content.
Why is vitamin K absorption better with fat?
Vitamin K is a fat-soluble vitamin, which means it dissolves in fat and is best absorbed by the body when consumed with dietary fats. This improves its bioavailability.
Is it possible to have a vitamin K deficiency?
Clinical vitamin K deficiency is rare in healthy adults but can occur in newborns and individuals with malabsorption disorders or those taking certain medications like blood thinners.
Are there fruits that are high in vitamin K?
While not as high as leafy greens, some fruits contain decent amounts of vitamin K, including blueberries, blackberries, and pomegranate seeds.
