Vitamin K: Food Sources & Daily Intake

Table of Contents

1. How to Read These Tables
2. Recommended Intakes & Upper Limits
3. Bioavailability & Absorption
4. Cooking & Storage
5. Vegetarian & Vegan Sources
6. Who Needs to Pay Attention
7. Key Research Papers
8. Connections
9. Featured Videos

How to Read These Tables

• Fat-soluble — absorbed with fat. Unlike water-soluble vitamins, vitamin K needs some dietary fat to be absorbed. A drizzle of olive oil or a vinaigrette on your greens genuinely improves how much you take up — plain steamed greens deliver less.
• %DV vs Adequate Intake (AI). The %DV column compares a serving against the U.S. Food and Drug Administration (FDA) Daily Value of 120 mcg. The age-specific guidance is the Adequate Intake (AI) — 120 mcg for men and 90 mcg for women — not a Recommended Dietary Allowance (RDA), because the data are too limited to set one. See the second table.
• Per 100 g vs per serving. Per-100 g lets you compare foods fairly; the serving size shown beside each food is what you actually eat. A single cup of cooked kale, collards or spinach clears several days’ worth in one go.

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Recommended Intakes & Upper Limits

Your personal target depends on age, sex and pregnancy. The Daily Value used for the %DV column above is a single label figure; the table below is the age-specific guidance.

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Bioavailability & Absorption

Vitamin K1 is wrapped inside the cell structures of plants, so the body absorbs only a modest fraction of it from raw greens — often well under a fifth of what’s on the label. Two things help a lot: fat in the same meal (the vitamin rides along with dietary fat into the bloodstream) and gentle cooking, which breaks down plant cell walls and frees the vitamin. This is the rare case where greens cooked in a little oil can beat the same greens raw. The K1 in plant oils and supplements is generally absorbed more readily than the K1 locked in vegetables.

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Cooking & Storage

Good news: vitamin K is one of the more stable vitamins. It holds up well to normal cooking, heat and storage — far better than fragile vitamin C — though prolonged exposure to light can slowly degrade it. Because it’s fat-soluble it does not leach away into cooking water the way water-soluble vitamins do, so boiling greens loses relatively little. Fat in the same meal increases K1 absorption — greens sautéed in olive oil, dressed with a vinaigrette, or eaten with avocado or nuts — and that pairing improves absorption more than any cooking method alone.

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Vegetarian & Vegan Sources

K1 is an easy win for plant-based eaters — every top source is a plant (kale, collards, spinach, chard, broccoli, herbs and plant oils), and a normal serving of greens far exceeds the Adequate Intake. The nuance is K2: apart from natto (fermented soybeans), the richest food source of K2 (menaquinone-7) — the Linus Pauling Institute lists about 998 mcg per 100 g — and fully plant-based, the menaquinone forms concentrate in animal foods (cheese, egg yolk, liver). Most evidence suggests adequate K1 covers the basics for healthy people, and the body converts some K1 to K2; K2 supplements are also sold.

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Who Needs to Pay Attention

This matters most for people taking warfarin or another vitamin-K-antagonist blood thinner. Warfarin works by blocking vitamin K, so what you eat directly affects how well it controls your clotting. The usual guidance is not to cut out greens but to keep vitamin K intake steady and consistent from week to week. Big swings (a sudden kale phase, then none) are what destabilize the dose and your international normalized ratio (INR). A large change in vitamin K intake — a major diet change or a new vitamin K supplement — shifts how strongly warfarin thins the blood, which is why the dose is adjusted by blood tests. Newer blood thinners (apixaban, rivaroxaban) are not affected by vitamin K. Outright deficiency is uncommon in adults; the group most at risk is newborns, who are born with very little — which is why a vitamin K shot at birth is standard and prevents dangerous bleeding. Because there is no documented toxicity, no Upper Limit exists for K1 or K2, but the warfarin interaction is real and important.

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Key Research Papers

1. NIH Office of Dietary Supplements — Vitamin K Fact Sheet (AI, DV, no UL, warfarin)
2. Linus Pauling Institute — Vitamin K Micronutrient Information Center
3. PubMed — vitamin K, phylloquinone, bone health and warfarin interaction. — Search PubMed

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Connections

• All Vitamins
• Vitamin K (Main Page)
• Vitamin K Benefits
• Vitamin K History
• Vitamin D3 (works with K for bone & arteries)
• Calcium (K helps direct it to bone)
• Kale
• Spinach

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