What are the sources of vitamin K more than one answer may be correct?

December 17, 2025 •

3 min read

According to the National Institutes of Health, most people in the United States get enough vitamin K from their diet, with deficiency being very rare. This essential nutrient, however, comes from multiple and varied sources, with both plant-based foods and animal products contributing to a healthy intake.

Quick Summary

Both plant-based foods and animal products are valid sources of vitamin K. Vitamin K1 is primarily found in leafy greens and some vegetable oils, while vitamin K2 is present in fermented foods, eggs, and certain meats.

Key Points

Two Primary Forms: Vitamin K exists as K1 (phylloquinone) found in plants and K2 (menaquinone) from fermented foods and animal products.
K1 from Plants: Dark green leafy vegetables like kale and spinach, along with vegetable oils, are top sources of vitamin K1.
K2 from Fermentation and Animals: Fermented soybeans (natto) are exceptionally high in K2, with smaller amounts found in eggs, liver, chicken, and cheese.
Gut Bacteria Contribution: Friendly bacteria in the large intestine also produce some vitamin K2, which the body can absorb.
Balanced Intake is Best: A varied diet that includes both plant-based and fermented/animal sources is the most effective way to meet your vitamin K needs.
Absorption with Fat: Because vitamin K is fat-soluble, consuming K1-rich foods with a source of fat can enhance absorption.

Understanding the Two Main Forms of Vitamin K

Vitamin K is not a single compound but a family of fat-soluble vitamins. The two most prominent forms are vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). They differ chemically and are found in different types of food, though both play crucial roles in blood clotting and bone health. A comprehensive diet that includes both forms is key to maximizing the health benefits of this essential vitamin.

Vitamin K1 (Phylloquinone) Sources

Vitamin K1 is the most common form found in the human diet and is synthesized by plants. It is most abundant in green, leafy vegetables, making these foods cornerstones of vitamin K intake. Its absorption can be enhanced when consumed with a source of dietary fat, such as a salad with a healthy oil-based dressing.

Dark, Leafy Greens: Kale, spinach, collard greens, Swiss chard, and mustard greens are exceptionally rich in vitamin K1.
Cruciferous Vegetables: Broccoli and Brussels sprouts also provide significant amounts.
Certain Fruits: While generally not as high in vitamin K1 as greens, some fruits contribute to overall intake, including blueberries, grapes, and kiwis.
Vegetable Oils: Oils like soybean and canola oil contain vitamin K1.

Vitamin K2 (Menaquinone) Sources

Vitamin K2 is primarily synthesized by bacteria, both in fermented foods and within the human gut, and is also found in some animal products. Different subtypes of K2 (MK-4 through MK-13) exist, each with unique dietary sources.

Fermented Foods: Natto, a traditional Japanese food made from fermented soybeans, is an exceptionally potent source of K2 (specifically MK-7). Other fermented products like sauerkraut and certain cheeses also contain K2, but in varying amounts.
Animal-Based Products: Foods from animal sources, including liver, chicken, eggs, and dairy products, contribute to K2 intake. Specifically, chicken liver and egg yolks are notable sources of the MK-4 subtype.

Bacteria in the Gut: A Natural Source

In addition to dietary sources, the beneficial bacteria residing in the large intestine can synthesize their own menaquinones (vitamin K2). While this endogenous production contributes to the body's overall vitamin K status, the amount absorbed and utilized is not sufficient to meet daily needs alone. It does, however, supplement the vitamin K derived from food sources.

Vitamin K Source Comparison Table

To simplify how to get vitamin K from different food types, here is a comparison of typical sources and the type of vitamin K they provide:


Food Category	Vitamin K Type	Examples	Best For...
Leafy Greens	Vitamin K1 (Phylloquinone)	Kale, Spinach, Collards	Highest dietary source of K1
Fermented Foods	Vitamin K2 (Menaquinone)	Natto, Sauerkraut, Hard Cheeses	Primary source of K2 (especially Natto)
Animal Products	Vitamin K2 (Menaquinone)	Chicken, Eggs, Liver, Cheese	Good sources of MK-4 subtype
Vegetable Oils	Vitamin K1 (Phylloquinone)	Soybean Oil, Canola Oil	Adding K1 to salads and cooking

Conclusion: A Balanced Diet for Multiple Sources

In conclusion, the question "What are the sources of vitamin K more than one answer may be correct?" is best answered by understanding that both plant-based foods rich in K1 and animal-based or fermented foods containing K2 are correct answers. Green leafy vegetables are the most concentrated source of vitamin K1, while fermented soybeans (natto) and certain animal products are excellent for K2. For most individuals, maintaining a balanced diet that includes a variety of these different food groups is the best way to ensure sufficient vitamin K intake. Always consult a healthcare professional for personalized dietary advice, especially if taking blood-thinning medications like warfarin, as consistent vitamin K intake is critical in these cases. For further reading on the essential functions of this vitamin, see the NIH Office of Dietary Supplements fact sheet.

Frequently Asked Questions

The primary food source for vitamin K1 is green leafy vegetables, such as kale, spinach, broccoli, and collard greens.

Natto, a Japanese dish made from fermented soybeans, is one of the richest dietary sources of vitamin K2.

Yes, animal products such as eggs, liver, and some cheeses contain vitamin K, specifically the K2 form.

Yes, certain vegetable oils like soybean and canola oil are good sources of vitamin K1.

Yes, bacteria in the human gut can produce small amounts of vitamin K2, which the body can absorb and utilize.

Since vitamin K is fat-soluble, consuming K1-rich vegetables with a source of fat, such as a salad dressing made with vegetable oil, can increase absorption.

While both are essential, they have slightly different roles in the body. K1 is more associated with blood clotting, while K2 is often linked to bone and cardiovascular health.