Natto. A fermented soybean dish most people outside Japan have never touched, carrying roughly 1,000 micrograms of vitamin K2 per 100 grams. If you meant vitamin K1 instead, the top everyday cooking green is collard greens at 623 micrograms per 100 grams, with raw spinach close behind at 483.
Two answers, because vitamin K is two different vitamins sharing one letter. Which one you are asking about changes the list completely, and most food charts only bother with half of it.
The short version
- Natto holds the most vitamin K2 of any common food.
- Collard greens and spinach are among the richest everyday sources of vitamin K1.
- K1 comes from green leaves. K2 comes from ferments and animal foods.
- Natto raised blood K2 about ten times higher than spinach raised K1.
- Adults need roughly 1 microgram per kilogram of body weight daily.
Vitamin K is two vitamins wearing one name
K1 is phylloquinone. It sits in green leaves, which is why every "eat your greens" article ends up being a vitamin K article without saying so. K2 is a family of menaquinones, and it turns up somewhere else entirely: in meat, liver, butter, egg yolk, cheese and fermented soy, according to the food database built by Schurgers and Vermeer at Maastricht University.
The body uses vitamin K as a cofactor. It switches on clotting factors in the liver, osteocalcin in bone, and matrix Gla protein in cartilage and the vessel wall, as set out in the 2007 study in Blood. The NHS puts it more simply: vitamin K is needed for blood clotting and wound healing, with some evidence it helps keep bones healthy.
The foods highest in vitamin K1, ranked
All values are micrograms per 100 grams, from USDA FoodData Central, for common greens eaten by the portion. Fresh parsley scores higher still, at 1,640 micrograms, but it goes on as a garnish, not a bowlful. Green wins, and it is not close.
- Collard greens, frozen then boiled: 623 micrograms
- Spinach, raw: 483 micrograms
- Collard greens, boiled from fresh: 407 micrograms
- Kale, frozen: 334 micrograms
- Brussels sprouts, raw: 177 micrograms
- Chinese broccoli, cooked: 85 micrograms
A 100 gram portion of raw spinach is a large bowl, so the number looks better on paper than it does on a plate. Cooked collards are the more realistic way to hit these figures, since a mound of leaves boils down to a few forkfuls.
The foods highest in vitamin K2
Natto sits so far ahead of everything else that the rest of the list is a footnote. In the Maastricht food database work, a 200 gram portion supplied 3.1 micromoles of K2, which works out at roughly 1,000 micrograms per 100 grams. Nothing else in an ordinary shop comes near that.
After natto, K2 turns up in hard cheese, curd cheese, egg yolk, liver and butter, all of them recorded in the same database. The quantities involved are far below natto's, and they shift with how the animal was fed and how the cheese was made.
Here is the part that trips people up. Most food tables are built around phylloquinone. The USDA one above lists only the MK-4 form of K2, and only for some foods, which leaves out the MK-7 that natto carries. Natto is listed at 23 micrograms of K1, which makes it look unremarkable, while its K2 content goes unrecorded. If you have ever wondered why K2 never appears in food charts, that is why. The data was never collected at the same scale.
Why natto beat spinach in the blood test
Six healthy men ate a meal of 400 grams of spinach and 200 grams of natto, with near-identical vitamin K doses coming from each food. Circulating K2 from the natto ran about ten times higher than circulating K1 from the spinach. Same vitamin on the label, very different outcome in the blood.
Part of that is timing and staying power. A 2007 comparison in Blood found K1 and natto-derived K2 supplements were both absorbed well, peaking around four hours, while the long-chain K2 had a far longer half-life. Over weeks of steady intake it built up to serum levels seven to eight times higher and produced more complete carboxylation of osteocalcin.
Spinach still earns its place. The greens on your plate and the ferment in the fridge do different jobs at different speeds, and a food chart that lumps them together under one heading hides that difference.
How much vitamin K you actually need
The NHS guidance is about 1 microgram per kilogram of body weight per day. A 75 kilogram man needs around 75 micrograms. The US adequate intake is set higher, at 120 micrograms a day for men and 90 for women.
Low intakes are common. A 2020 paper in Foods opens by noting that national nutrition surveys have found more than half of adults in the UK and the US have low vitamin K intakes. That is a shortfall against a target most people have never heard of, for a nutrient nobody markets.
Two practical notes. Vitamin K is fat soluble, so greens eaten with olive oil or butter give up more of it than greens eaten dry. And if you take warfarin, sudden swings in vitamin K intake from food or supplements can raise or lower the drug's effect, so take any change to your greens habit or your supplements to your doctor before you make it.
If natto is never happening
Most people will not start eating fermented soybeans for breakfast, and that is a fair position. The realistic version looks like this: leafy greens several times a week with some fat alongside them, plus whatever K2 comes with the cheese, egg yolks and butter already in your diet. That covers the clotting requirement comfortably.
A daily multivitamin sits underneath all of that as a backstop. Fireblood carries vitamin K1 as phylloquinone at 120 micrograms and vitamin K2 as menaquinone-4 at 120 micrograms per scoop. That puts a floor under a normal week of eating. The greens still do the heavy lifting. The same logic applies to food sources of vitamin C, where the diet carries most of the load and the supplement covers what it misses.
Vitamin K also has a habit of being discussed only as a partner to something else, usually vitamin D, which is a conversation worth having separately.
The honest answer to "what food is highest in vitamin K" is a dish most readers will never order. The useful answer is that a bowl of cooked collards takes ten minutes and covers the US adequate intake five times over.
Frequently asked questions
What food is highest in vitamin K?
Natto, a fermented soybean dish, carries roughly 1,000 micrograms of vitamin K2 per 100 grams. Nothing else in an ordinary shop comes near that for K2.
What food is highest in vitamin K1?
Among greens eaten by the portion, collard greens lead at 623 micrograms per 100 grams when frozen then boiled, with raw spinach close behind at 483 micrograms per 100 grams. Fresh parsley scores higher at 1,640 micrograms, but it is eaten as a garnish.
How much vitamin K do I need a day?
NHS guidance is about 1 microgram per kilogram of body weight per day, so a 75 kilogram man needs around 75 micrograms. The US adequate intake is 120 micrograms a day for men and 90 for women.
Is vitamin K1 or K2 better absorbed?
In a 2007 supplement study, both were absorbed well and peaked in the blood around four hours after intake. Natto-derived long-chain K2 has a much longer half-life, building up to serum levels seven to eight times higher over weeks of steady intake.
Why is vitamin K2 missing from most food charts?
Most food tables are built around phylloquinone, which is vitamin K1. USDA lists only the MK-4 form of K2, and only for some foods, so natto is listed at 23 micrograms of K1 while its MK-7 goes unrecorded.
Fireblood is a daily vitamin and mineral powder containing K1 and K2 alongside 37 other nutrients, built to cover the nutritional floor across the whole label. The full formula is on the product page if you want to read it.
