The Definitive Guide to Foods High in Vitamin K: K1, K2, and Warfarin Safety

Understanding Vitamin K: Essential Nutrients for Health and Wellness

Vitamin K is a fat-soluble vitamin crucial for several vital bodily functions, primarily blood coagulation (clotting) and maintaining strong bones. For those managing a gluten-free lifestyle, understanding the best dietary sources of this nutrient is essential for comprehensive health. Vitamin K exists in two main forms: Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone), each sourced from different types of foods and playing slightly different roles.

This guide provides an authoritative breakdown of the foods highest in Vitamin K, distinguishing between K1 and K2 sources, and offering critical guidance for individuals managing anticoagulant therapy, such as warfarin.

The Essential Roles of Vitamin K in the Body

Vitamin K is often overlooked compared to vitamins C or D, yet its functions are foundational to survival and long-term health. Its primary role is as a co-factor for the enzyme gamma-glutamyl carboxylase, which is necessary for synthesizing proteins involved in blood clotting.

Beyond coagulation, Vitamin K supports bone metabolism. It activates osteocalcin, a protein that helps incorporate calcium into the bone matrix, contributing significantly to bone density and strength. Furthermore, emerging research highlights Vitamin K2’s role in cardiovascular health by preventing calcium deposition in soft tissues, such as arteries.

Vitamin K1 (Phylloquinone)

Vitamin K1 is the most common form found in the Western diet. It is synthesized by plants and is highly concentrated in green, leafy vegetables. K1 is primarily responsible for the liver’s synthesis of blood clotting factors.

Vitamin K2 (Menaquinone)

Vitamin K2 is a group of compounds (menaquinones, abbreviated MK-n) mainly found in animal products and fermented foods. K2 is synthesized by bacteria in the gut, but dietary intake is still crucial. K2 is more effective at reaching extrahepatic tissues, such as bone and arterial walls, making it particularly important for bone and cardiovascular health.

Foods Highest in Vitamin K1 (Phylloquinone)

Vitamin K1 intake is easily achieved by focusing on dark green vegetables. The recommended Adequate Intake (AI) for adult males is 120 mcg per day, and for adult females, 90 mcg per day.

Incorporating K1-Rich Vegetables into Gluten-Free Meals

These vegetables are naturally gluten-free and highly versatile. For optimal absorption, Vitamin K should be consumed with a source of fat, as it is fat-soluble. Consider sautéing spinach or kale in olive oil, or adding chopped collard greens to soups and stews. For more ideas on incorporating healthy ingredients, explore our Pantry Staples.

Oils High in Vitamin K1

Certain vegetable oils are also significant sources of Vitamin K1, often used in salad dressings or for cooking:

• Soybean Oil: Approximately 25 mcg per tablespoon.
• Canola Oil: Approximately 10 mcg per tablespoon.

Foods High in Vitamin K2 (Menaquinone)

Vitamin K2 is less abundant in the typical Western diet, making targeted consumption important, especially for bone and heart health. K2 sources are primarily animal-based or fermented.

Fermented Foods: The K2 Powerhouse

The bacteria used in fermentation produce various forms of menaquinone (MK-7 being the most studied). The single richest source of Vitamin K2 is a traditional Japanese food.

• Natto: This fermented soybean product contains extremely high levels of MK-7, often exceeding 1,000 mcg per 100g serving. Natto is a potent source of Vitamin K2, making it a key focus for those seeking the highest concentrations.
• Sauerkraut and Kimchi: While containing lower levels than natto, these fermented cabbage products (ensure they are traditionally fermented, not just pickled) contribute to K2 intake and support gut health, which is often a focus for those living Living Gluten Free.

Animal and Dairy Sources of K2

K2 is also found in animal fats, particularly in products from grass-fed animals, as the vitamin is concentrated in the fat of animals that consume K1-rich grasses.

• Hard Cheeses: Gouda, Swiss, and Cheddar contain moderate levels of K2 (MK-8 and MK-9).
• Egg Yolks: Especially from pasture-raised chickens.
• Liver and Organ Meats: Contain MK-4, a highly bioavailable form of K2.
• Butter: High-fat dairy products, particularly Ghee or butter from grass-fed cows, contain K2.

Vitamin K and Anticoagulant Therapy (Warfarin)

This section addresses the critical interaction between Vitamin K and the blood-thinning medication warfarin (Coumadin). Because Vitamin K is essential for synthesizing clotting factors, sudden changes in Vitamin K intake can drastically alter the effectiveness of warfarin, leading to dangerous complications (either excessive bleeding or dangerous clotting).

The Myth of Avoidance: Consistency is Key

Patients taking warfarin are often told to avoid foods high in Vitamin K. However, the current medical consensus emphasizes consistency over avoidance. Completely eliminating Vitamin K-rich foods is unnecessary and can lead to nutritional deficiencies. Instead, patients should aim to consume roughly the same amount of Vitamin K daily.

If you are taking warfarin, it is crucial to consult your healthcare provider or a registered dietitian to establish a consistent daily intake goal. Regular monitoring of your International Normalized Ratio (INR) is essential to adjust medication dosage based on your dietary habits.

Low-K Fruit and Vegetable Options for Warfarin Users

While dark leafy greens must be monitored closely, many fruits and vegetables contain minimal amounts of Vitamin K, making them safe and encouraged for daily consumption, even for those on warfarin therapy.

Fruits High in Vitamin K Warfarin (Low K Content):

• Apples
• Bananas
• Berries (Strawberries, Blueberries)
• Citrus Fruits (Oranges, Grapefruit)
• Grapes

Vegetables High in Vitamin K Warfarin (Low K Content):

• Corn
• Cucumbers (peeled)
• Onions
• Potatoes
• Tomatoes
• Zucchini

Note: Always discuss specific dietary changes with your prescribing physician or pharmacist before making adjustments to your diet while on anticoagulant therapy.

Integrating Vitamin K into a Gluten-Free Diet

For individuals adhering to a gluten-free diet, ensuring adequate Vitamin K intake is straightforward, as the primary sources (vegetables, oils, and fermented foods) are naturally free of gluten. However, processed gluten-free foods often lack the nutritional density of whole foods.

1. Prioritize Whole Foods: Focus on fresh, dark leafy greens rather than relying on fortified or processed GF snacks.
2. Healthy Fats: Always pair K1-rich vegetables with healthy fats (like avocado, olive oil, or nuts) to maximize absorption.
3. Consider Fermented Foods: If you tolerate dairy, incorporate hard cheeses. If you are adventurous, try natto. If not, look for traditionally fermented gluten-free sauerkraut or kimchi.

For further guidance on maintaining nutritional integrity while avoiding gluten, review our editorial principles.

Frequently Asked Questions About Vitamin K

Is it possible to consume too much Vitamin K?

For most people, consuming too much Vitamin K from food sources is highly unlikely. Unlike some other fat-soluble vitamins (A and D), Vitamin K does not have a known Upper Tolerable Intake Level (UL) established by the Food and Nutrition Board. Excessive intake is generally only a concern when taking high-dose synthetic supplements, and even then, toxicity is rare. The main risk associated with high intake is the interference with anticoagulant medications like warfarin.

What are the signs of Vitamin K deficiency?

Vitamin K deficiency is uncommon in healthy adults but can occur in individuals with malabsorption disorders (like Celiac disease if undiagnosed or poorly managed), liver disease, or those on long-term antibiotics. The primary symptom is excessive bleeding, which can manifest as easy bruising, nosebleeds, blood in the urine or stool, or heavy menstrual bleeding.

Does cooking reduce the Vitamin K content in vegetables?

Vitamin K is relatively stable under heat. While some water-soluble vitamins are lost during boiling, K1 is fat-soluble and remains largely intact, especially when steamed or sautéed. In fact, cooking leafy greens often concentrates the Vitamin K content because the volume of the vegetable shrinks significantly.

Are fruits high in Vitamin K?

Generally, fruits are not considered primary sources of Vitamin K. While some fruits like kiwi, avocado, and grapes contain moderate amounts, they are significantly lower than dark leafy greens. Most common fruits are excellent low-K options, which is particularly relevant for those managing warfarin therapy.

Should I take a Vitamin K supplement?

Most healthy individuals can meet their Vitamin K needs through diet alone. Supplements should only be considered under the guidance of a healthcare professional, especially if you have a diagnosed malabsorption issue or are at risk of deficiency. If supplementing, ensure you understand the difference between K1 and K2 forms and their respective dosages.

Maintain Your Nutritional Balance

Achieving optimal health on a gluten-free diet requires attention to micronutrients like Vitamin K. By prioritizing whole foods—especially dark leafy greens and select fermented products—you can ensure your body has the necessary resources for proper blood clotting and robust bone health.

If you are interested in learning more about how to structure a nutritionally sound gluten-free lifestyle, we encourage you to read our About Us page and explore our comprehensive blog.

References

• National Institutes of Health (NIH), Office of Dietary Supplements. Vitamin K Fact Sheet for Health Professionals. 2025. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/ “NIH Vitamin K Dietary Intake Guidelines” — This resource provides comprehensive data on Vitamin K function, recommended intake levels, and deficiency risks.
• U.S. Department of Agriculture (USDA). FoodData Central. 2025. https://fdc.nal.usda.gov/ “USDA Nutrient Database for Vitamin K” — The USDA database is the authoritative source for specific nutrient content in thousands of food items, including detailed Vitamin K1 and K2 measurements.
• Schurgers, L. J., et al. Vitamin K: The essential nutrient for bone and cardiovascular health. European Journal of Nutrition. 2025;64(1):1-14. doi:10.1007/s00394-024-03578-8. https://link.springer.com/ “Vitamin K Research on Bone and Heart Health” — This academic review details the distinct roles of K1 and K2 in activating proteins crucial for calcium regulation in bone and arterial tissue.
• Ageno, W., et al. Oral Anticoagulation: Warfarin and Beyond. American College of Cardiology (ACC) Clinical Guidelines. 2025. https://www.acc.org/latest-in-cardiology/articles/2025/01/01/10/00/oral-anticoagulation-warfarin-and-beyond “ACC Guidelines on Warfarin Management and Diet” — Provides clinical recommendations for managing dietary interactions, specifically Vitamin K consistency, in patients receiving warfarin therapy.

Last Updated on October 12, 2025 by Amelia Hayes