What is the highest source of vitamin K? Finding the Answer in Your Diet

November 10, 2025 •

4 min read

While severe vitamin K deficiency is rare in the US, many people don't consume enough for optimal bone and heart health. To maximize intake, it's key to know what is the highest source of vitamin K and how different food types provide this vital nutrient. The answer is nuanced, depending on whether you're seeking Vitamin K1 from plants or Vitamin K2 from fermented foods.

Quick Summary

The highest single source of vitamin K depends on the form: natto provides the most K2, while cooked dark leafy greens like collard greens are exceptionally rich in K1. Learn about the distinct sources of Vitamin K1 and K2 and their crucial roles in blood clotting and bone health.

Key Points

Natto is the highest K2 source: Fermented soybeans (natto) are the most concentrated food source of vitamin K2, providing a massive amount per serving.
Cooked greens are the highest K1 source: When considering typical serving sizes, cooked dark leafy greens like collard greens, spinach, and kale are among the highest sources of vitamin K1.
Dried herbs are extremely potent: Per 100g, dried herbs like basil and sage offer the most vitamin K1, but they are consumed in small quantities.
Different forms, different sources: The answer to 'what is the highest source of vitamin K?' is divided between K1-rich plants and K2-rich fermented/animal products.
Absorption is enhanced with fat: As a fat-soluble vitamin, pairing vitamin K sources with dietary fat improves absorption.
Variety is key: A balanced intake of various vitamin K-rich foods ensures adequate levels for blood clotting and bone health.
Medication considerations: Those on blood thinners like warfarin must maintain a consistent vitamin K intake and consult a doctor.

The Importance of Vitamin K in Your Diet

Vitamin K is an essential fat-soluble nutrient, meaning it's best absorbed when consumed with fat. It plays a critical role in several physiological processes, most notably blood clotting, where it helps produce the proteins necessary to stop bleeding. Beyond this well-known function, vitamin K is vital for maintaining strong, healthy bones by activating proteins like osteocalcin, which helps with calcium utilization. There is also ongoing research into its potential benefits for heart health, specifically its role in preventing the mineralization, or hardening, of arteries.

Understanding the Two Types: K1 vs. K2

To determine the highest source, it's crucial to distinguish between the two main forms of vitamin K found in food:

Vitamin K1 (Phylloquinone): Primarily found in plant-based foods, especially green leafy vegetables. The majority of dietary vitamin K comes from this form.
Vitamin K2 (Menaquinones): Occurs in animal products and fermented foods. It is also produced by the bacteria in your gut. While K1 and K2 share some functions, they are metabolized differently in the body and may offer unique health benefits.

The Highest Sources of Vitamin K1

When it comes to the plant-based Vitamin K1, the most potent sources are consistently dark, leafy greens. Cooking these vegetables often makes the vitamin K content more concentrated per serving due to water loss. The highest concentrations are found in:

Dried Herbs: While not typically consumed in large volumes, dried basil, dried sage, and fresh parsley are extremely concentrated sources of vitamin K1 per 100 grams. A small amount can contribute significantly to daily intake.
Cooked Collard Greens: For a practical, high-volume serving, a half-cup of cooked collard greens contains an impressive amount of vitamin K1, often exceeding 500 mcg.
Cooked Spinach: A nutrient powerhouse, cooked spinach is another top contender, offering hundreds of micrograms per cooked cup.
Kale: Another popular leafy green, especially when cooked, provides a substantial dose of vitamin K1.

The Highest Sources of Vitamin K2

For those looking for the K2 form, the list of foods is different, dominated by fermented items and certain animal products. The undisputed champion for Vitamin K2 content is a traditional Japanese food:

Natto: This fermented soybean dish is by far the highest known food source of Vitamin K2 (specifically MK-7), providing a massive amount in a single serving. While its strong, pungent flavor can be polarizing, it is an exceptionally concentrated source.
Cheese: Some types of cheese, particularly soft and blue cheeses, contain notable amounts of Vitamin K2. The fermentation process is key to its production.
Goose Liver: While less common in many diets, goose liver is another concentrated source of Vitamin K2.
Egg Yolks and Meats: Smaller amounts of Vitamin K2 can be found in egg yolks and some animal meats, but the concentration is much lower than in natto.

Maximizing Vitamin K Absorption

Since vitamin K is a fat-soluble vitamin, simply eating these foods may not be enough to get the maximum benefit. Pairing them with a source of dietary fat can significantly improve absorption. For example, drizzling olive oil over a spinach salad or sauteing kale with a bit of oil can increase the amount of vitamin K your body can absorb.

Comparison of Top Vitamin K Sources (per 100g)


Food Source	Form of Vitamin K	Vitamin K Content (mcg/100g)	Notes
Dried Basil	K1	~1715	Extremely concentrated, used in small amounts.
Dried Sage	K1	~1715	Similar to basil, very high concentration.
Fresh Parsley	K1	~1640	Very high concentration, also used as a garnish.
Natto (Fermented Soybeans)	K2 (MK-7)	~998	The highest K2 source, strong flavor.
Raw Swiss Chard	K1	~830	One of the highest raw green sources.
Cooked Collard Greens	K1	~623	Very high per cooked volume.
Cooked Spinach	K1	~541	One of the highest cooked green sources.
Soft Cheese	K2	~506	Good source for those avoiding fermented soy.

Conclusion: Finding the 'Highest' Source

Ultimately, the 'highest' source of vitamin K depends on the type you seek and your dietary habits. For a concentrated dose of Vitamin K2, natto is unrivaled, though its taste is an acquired one. For the more common Vitamin K1, the highest concentrations per gram are found in dried herbs like basil or fresh parsley, while cooked dark leafy greens like collard greens and spinach provide substantial amounts in more typical serving sizes. For most people, incorporating a variety of these foods is the most practical way to meet daily needs and reap the health benefits for blood clotting, bone, and heart health.

For more in-depth information, you can explore detailed factsheets from the National Institutes of Health.

Frequently Asked Questions

Vitamin K1 (phylloquinone) is mainly found in green leafy vegetables, while vitamin K2 (menaquinone) is in animal products and fermented foods like natto. They are absorbed and metabolized differently, and K2 is also produced by gut bacteria.

For most people, getting vitamin K from a balanced diet is sufficient and preferable, as foods also provide other beneficial nutrients. Supplements may be recommended by a doctor for specific health conditions or deficiencies.

Since vitamin K is fat-soluble, you can increase its absorption by eating vitamin K-rich foods with a source of healthy fat. For example, add olive oil to a salad with spinach or cook greens with a little oil.

Per typical cooked serving, collard greens and spinach are extremely high in vitamin K1. However, per 100g, raw Swiss chard and concentrated dried herbs like basil are higher still.

Yes, vitamin K can interact with blood-thinning medications like warfarin, as it plays a role in blood clotting. If you are on this medication, it is crucial to maintain a consistent daily intake of vitamin K and consult your doctor before making any dietary changes.

The main benefits of vitamin K include its essential role in blood clotting, promoting strong bone health by improving calcium usage, and its potential to support cardiovascular health.

Natto is the most concentrated source of vitamin K2, but it's not the only one. Other sources include soft cheeses, goose liver, egg yolks, and some fermented products. Bacteria in the gut also produce some K2.