What Food Has the Largest Amount of Vitamin K?

One 3-ounce serving of the fermented soybean dish natto delivers a staggering 850 micrograms of vitamin K, making it the top contender for what food has the largest amount of vitamin K. This fat-soluble vitamin is essential for crucial bodily functions, including blood clotting and bone metabolism. While natto is the most concentrated source, many other foods can help meet your daily needs.

Quick Summary

This article explores the single food highest in vitamin K, reveals the powerful health benefits of this nutrient, and details other top dietary sources. Learn how different forms of vitamin K support blood and bone health and who needs to be particularly mindful of their intake.

Key Points

• Natto is the most concentrated source: A 3-ounce serving of the fermented soybean dish natto contains 850 mcg of vitamin K, mainly the K2 form.

• Leafy greens are widely available sources: Cooked kale, collard greens, and spinach are exceptionally high in vitamin K1 and are easy to incorporate into many meals.

• Vitamin K is fat-soluble: Pairing vitamin K-rich foods with healthy fats, like olive oil, helps maximize absorption.

• Supports blood clotting and bone health: Vitamin K is essential for producing proteins vital for blood coagulation and the mineralization of bones.

• Watch intake with blood thinners: Individuals taking warfarin must maintain a consistent vitamin K intake to avoid impacting the medication's effectiveness.

Natto: The Unquestioned Vitamin K King

Without a doubt, the fermented Japanese soybean dish known as natto holds the title for the food with the highest concentration of vitamin K. This is not just any vitamin K, but the highly bioavailable menaquinone-7 (MK-7) form, which is a type of vitamin K2. One small, 3-ounce serving of natto can provide over 700% of the recommended Daily Value (DV) of vitamin K. While its pungent smell and acquired taste mean it isn't a staple in most Western diets, its nutritional value is undeniable. The fermentation process is responsible for producing these potent levels of K2, which studies suggest may be particularly beneficial for bone health.

The Two Types of Vitamin K: K1 vs. K2

To understand the full spectrum of vitamin K sources, it's important to distinguish between the two primary types: phylloquinone (K1) and menaquinones (K2).

Vitamin K1 (Phylloquinone)

Found primarily in leafy green vegetables, K1 is the most common dietary form. It plays a critical role in the liver's production of blood-clotting proteins. Some of the best K1 sources include:

• Cooked leafy greens (kale, spinach, collards, turnip greens)
• Raw leafy greens (Swiss chard, dandelion greens)
• Cruciferous vegetables (broccoli, Brussels sprouts)
• Herbs (parsley, basil, thyme)

Vitamin K2 (Menaquinones)

K2 is less common in the average diet and is found in fermented foods and animal products. It is thought to be more involved in bone and cardiovascular health. Aside from natto, other sources include:

• Hard cheeses (Gouda, Emmental)
• Goose liver
• Egg yolks
• Chicken meat
• Certain cured meats

The Best Vitamin K Sources for a Standard Diet

For those not planning to incorporate natto into their meals, numerous other foods offer substantial vitamin K. The key is to include a variety of these foods regularly, as the vitamin is fat-soluble and best absorbed with a source of fat.

Food (per 100g)	Vitamin K (mcg)	Form of Vitamin K	Notes
Natto	998	K2	Highest concentration, strong taste.
Raw Swiss Chard	830	K1	Excellent, accessible plant source.
Cooked Collard Greens	623	K1	Extremely high per serving when cooked.
Cooked Mustard Greens	593	K1	Another high-potency cooked green.
Cooked Spinach	541	K1	Versatile and easily added to many dishes.
Raw Spinach	483	K1	Good raw source for salads and smoothies.
Cooked Kale	419	K1	A popular green with great vitamin K content.
Goose Liver	369	K2	A potent animal source of K2.
Hard Cheeses	43-73	K2	Content varies by type and processing.
Broccoli	141	K1	Common cruciferous vegetable.

Health Benefits of a Vitamin K-Rich Diet

Proper intake of vitamin K is associated with several key health benefits, primarily related to its function in binding calcium.

• Blood Coagulation: Vitamin K acts as a cofactor for enzymes that produce coagulation factors II, VII, IX, and X in the liver, which are crucial for the blood clotting process. This is why deficiencies can lead to increased bleeding.
• Bone Health: Vitamin K is a co-factor for the protein osteocalcin, which is integral to building and maintaining strong bones. Adequate levels are linked to reduced risk of osteoporosis and fractures, especially in postmenopausal women.
• Cardiovascular Health: The vitamin K-dependent protein MGP (Matrix Gla Protein) helps to prevent the calcification of arteries and soft tissues. Therefore, a sufficient intake may contribute to a reduced risk of cardiovascular disease.

Who Needs to Be Careful with High Vitamin K Foods?

While high vitamin K intake is generally safe for most people, a very specific group needs to monitor their consumption closely: individuals on blood-thinning medication like warfarin. Warfarin works by antagonizing, or inhibiting, vitamin K activity. A sudden increase or decrease in vitamin K intake can disrupt the medication's effectiveness, making consistent intake crucial. Any dietary changes for someone on warfarin should be discussed with a doctor. For the general population, no toxicity has been reported from high doses of K1 or K2 through food.

Conclusion

From the concentrated power of natto to the more accessible abundance in leafy greens like spinach and collards, the options for increasing your vitamin K intake are plentiful. This essential fat-soluble vitamin plays a vital role in keeping your blood healthy and your bones strong. By incorporating a variety of these nutrient-rich foods into your diet, most individuals can easily meet their daily needs. Remember to pair plant-based sources with a healthy fat, like olive oil, for optimal absorption. For those on blood thinners, consulting a healthcare provider to manage intake is always the safest approach to benefiting from vitamin K's many advantages.

NIH Office of Dietary Supplements provides additional trusted information on vitamin K and its sources.

Frequently Asked Questions

Does spinach have a lot of vitamin K?

Yes, spinach is an excellent source of vitamin K, with one cup of raw spinach providing 145 mcg. Its content becomes even more concentrated when cooked.

Is it possible to consume too much vitamin K?

For most healthy individuals, no. There is no known toxicity associated with high doses of vitamin K from food sources, and the body can excrete excess amounts.

What is the difference between vitamin K1 and K2?

Vitamin K1 is primarily found in plant foods like leafy greens and is crucial for blood clotting. Vitamin K2 is found in fermented foods and animal products and is important for bone and cardiovascular health.

Can cooking affect the vitamin K content in food?

Cooking does not destroy vitamin K, as it is a fat-soluble vitamin. In many cases, cooking actually concentrates the vitamin K content in leafy greens, so a cooked portion may have more than a raw one by volume.

Are there any fruits high in vitamin K?

While not as concentrated as leafy greens, some fruits do contain decent amounts of vitamin K, including blueberries, blackberries, and prunes.

Who should monitor their vitamin K intake carefully?

Individuals on blood-thinning medications like warfarin should monitor their vitamin K intake. Sudden fluctuations can affect the medication's efficacy and should be managed with medical supervision.

How can I improve my body's absorption of vitamin K?

Because vitamin K is fat-soluble, consuming it with a small amount of fat significantly improves its absorption. For example, add a drizzle of olive oil to a salad with leafy greens.