What food group is vitamin K in? Understanding its Dietary Sources

October 31, 2025 •

4 min read

An estimated one-third of the U.S. population has a vitamin K intake below the recommended Adequate Intake, though severe deficiency is rare in adults. To avoid suboptimal intake and support crucial bodily functions like blood clotting and bone health, it is important to know what food group is vitamin K in.

Quick Summary

Vitamin K is found in several food groups, most notably leafy green vegetables for vitamin K1 and fermented foods, meat, and dairy for vitamin K2. Consuming a varied diet ensures adequate intake for blood clotting, bone health, and heart function.

Key Points

Two Primary Forms: Vitamin K exists as K1 (phylloquinone), mainly from plants, and K2 (menaquinones), from animal and fermented foods.
Best K1 Sources: Dark leafy greens like kale and spinach are among the richest dietary sources of vitamin K1.
Key K2 Sources: Fermented soybeans (natto), certain cheeses, and meat/liver are top sources of vitamin K2.
Crucial Functions: Vitamin K is essential for blood clotting and supports bone health by activating specific proteins.
Warfarin Interaction: Individuals on blood-thinning medication like warfarin must maintain consistent vitamin K intake to avoid dangerous interactions.
Fat-Soluble: Because it is a fat-soluble vitamin, consuming K1 sources with a healthy fat can improve absorption.

Vitamin K is a vital, fat-soluble nutrient that plays a crucial role in several physiological processes, including blood clotting and bone metabolism. It comes in two primary forms: vitamin K1 (phylloquinone) and vitamin K2 (menaquinones), each found in different food groups. By understanding the sources of each form, you can ensure a balanced intake of this essential vitamin.

Vitamin K1: The Plant-Based Source

Most of the vitamin K consumed in a typical diet comes from vitamin K1, also known as phylloquinone. This form is predominantly found in plant-based foods, especially dark, leafy green vegetables. Since vitamin K is fat-soluble, consuming these vegetables with a source of healthy fat, like olive oil in a salad, can enhance absorption.

Vegetables

Green leafy vegetables are the most potent sources of vitamin K1. Some of the best options include:

Kale
Spinach
Collard greens
Turnip greens
Beet greens
Swiss chard

Other vegetables also contain significant amounts of vitamin K1:

Broccoli
Brussels sprouts
Cabbage
Asparagus
Green beans

Other Plant Sources

Beyond vegetables, other plant-based items contribute to vitamin K1 intake:

Vegetable oils, such as soybean and canola oil.
Fruits like blueberries, figs, grapes, and prunes also provide modest amounts.

Vitamin K2: The Animal and Fermented Source

Vitamin K2, or menaquinones, is a different family of compounds produced by bacteria. It is found in animal products and fermented foods. While the body can produce some K2 from K1, obtaining it directly from dietary sources is important, as K2 may have distinct benefits for extrahepatic tissues, such as bones and blood vessels.

Fermented Foods

Certain fermented foods are particularly rich in vitamin K2:

Natto: A traditional Japanese dish of fermented soybeans, natto is one of the richest sources of K2, specifically the MK-7 subtype.
Cheese: Various types of cheese contain K2, including hard cheeses like Cheddar and soft cheeses like Brie.
Sauerkraut: Fermented cabbage can also provide a good source of K2.

Animal Products

Some animal-based foods contain vitamin K2, specifically the MK-4 subtype.

Meat and Poultry: Liver and dark meat from chicken are notable sources of vitamin K2.
Eggs: The yolks from eggs provide vitamin K2, though the amount can vary.
Dairy: Whole milk and butter from grass-fed animals may also contain K2.

Health Benefits of Vitamin K

Ensuring adequate vitamin K intake through a varied diet supports overall health, with key benefits including:

Blood Clotting: Vitamin K is required for the liver to produce several key proteins, or clotting factors, that allow blood to clot and wounds to heal properly.
Bone Health: The vitamin is essential for synthesizing proteins that help regulate bone mineralization and keep bones strong. Research suggests a correlation between higher vitamin K intake and lower risk of fractures and improved bone density.
Cardiovascular Health: Vitamin K activates proteins that help prevent the calcification of arteries, which is a major risk factor for heart disease.

Vitamin K1 vs. Vitamin K2: A Comparison


Feature	Vitamin K1 (Phylloquinone)	Vitamin K2 (Menaquinones)
Primary Source	Plant-based foods, especially leafy greens and vegetable oils.	Animal products (meat, eggs, dairy) and fermented foods.
Absorption Rate	Less efficiently absorbed from plants; absorption improved with fat.	Generally better absorbed by the body than K1.
Half-Life	Relatively short half-life of 1–2 hours.	Longer half-life (MK-7, ~72 hours), allowing for greater distribution.
Distribution	Primarily transported to the liver to regulate coagulation.	Distributed to extra-hepatic tissues like bone and arteries.
Primary Function	Supports blood clotting functions in the liver.	May have a more significant role in long-term bone and cardiovascular health.

Dietary Recommendations and Special Considerations

For most healthy adults, a balanced diet is sufficient to meet their daily vitamin K needs. For adult men, the Adequate Intake (AI) is 120 micrograms per day, and for adult women, it is 90 micrograms per day.

It is important to note that sudden changes in vitamin K intake can interfere with the effectiveness of certain medications, particularly the anticoagulant warfarin. Individuals on this medication should maintain a consistent intake of vitamin K and consult with their healthcare provider or dietitian before making any major dietary changes.

Conclusion

In conclusion, vitamin K is not limited to a single food group but is available from both plant and animal sources. Vitamin K1 is abundant in green leafy vegetables and certain oils, while vitamin K2 is found in fermented foods, meats, and dairy. A diversified diet rich in these food groups ensures that you are receiving the necessary amounts of this essential nutrient to support blood clotting, maintain strong bones, and promote cardiovascular health. While deficiencies are uncommon in healthy adults, knowing the best sources is key to a nutrient-dense and health-promoting diet. For more detailed information on vitamin K, consult authoritative sources such as the NIH Office of Dietary Supplements.

Frequently Asked Questions

The best food sources of vitamin K1 are dark green leafy vegetables such as kale, spinach, collard greens, turnip greens, and Swiss chard. Other good sources include broccoli, Brussels sprouts, cabbage, and certain vegetable oils.

Vitamin K2 is primarily found in fermented foods like natto (fermented soybeans), sauerkraut, and various cheeses. Animal products such as meat, liver, and eggs also contain menaquinones (vitamin K2).

Vitamin K1 is mainly sourced from plants and is primarily used by the liver for blood clotting. Vitamin K2 comes from animal and fermented products and is more effectively utilized by extra-hepatic tissues like bones and arteries, giving it a potentially more significant role in long-term bone and heart health.

Severe vitamin K deficiency is rare in adults, but can lead to impaired blood clotting. Symptoms may include easy bruising, excessive bleeding from wounds or gums, nosebleeds, and blood in urine or stool. A deficiency can also weaken bones.

Vitamin K and warfarin work in opposition; warfarin blocks the activity of vitamin K. Individuals on warfarin need to maintain a consistent daily intake of vitamin K from food, as large, sudden changes can interfere with the medication's effectiveness and lead to dangerous bleeding or clotting.

While it's important to have a consistent intake, you don't necessarily need to consume vitamin K every single day. Your body stores any excess vitamin K in the liver for future use.

Vitamin K deficiency is rare in healthy adults who eat a balanced diet. However, those with malabsorption disorders, such as celiac disease or cystic fibrosis, or those taking certain medications, are at higher risk.