Green leafy vegetables are the single best source of vitamin K, and just one cup of raw spinach (about 145 micrograms) or frozen kale (about 224 micrograms) can meet or exceed most adults’ daily needs. Vitamin K comes in two main forms: K1, found in plants, and K2, found in fermented and animal-based foods. Both play essential roles in blood clotting, bone health, and keeping calcium where it belongs in your body.
Two Forms of Vitamin K, Different Foods
Vitamin K1 (phylloquinone) is the form most abundant in the diet, and it comes almost entirely from plant foods. It’s the main player in blood clotting, helping your body produce the proteins that stop bleeding when you’re injured. It also supports a bone protein involved in bone mineralization and turnover.
Vitamin K2 (menaquinones) is produced by bacteria, which is why it shows up in fermented and animal-based foods rather than fresh vegetables. K2 is getting increasing attention for its potential role in cardiovascular health. A vitamin K-dependent protein found in blood vessels, cartilage, and bone may help prevent calcium from depositing in artery walls, and K2 appears to be particularly involved in activating that protein.
Leafy Greens: The Richest Sources
If you’re looking to boost your vitamin K intake, dark leafy greens deliver far more per serving than any other food group. Here’s what you get from common options, based on USDA data:
- Spinach (raw, 1 cup): 145 micrograms
- Spinach (canned, 1 cup): 891 micrograms
- Kale (frozen, 1 cup): 224 micrograms
- Kale (raw, 1 cup): 82 micrograms
Other excellent K1 sources include collard greens, Swiss chard, turnip greens, and broccoli. Even iceberg lettuce, which isn’t especially nutrient-dense overall, ranks among the most common vitamin K sources in the American diet simply because people eat so much of it. A large salad with mixed greens can easily provide several days’ worth of vitamin K in a single sitting.
Cooking Oils, Herbs, and Other Plant Sources
Leafy greens aren’t the only plant foods worth noting. Soybean oil and canola oil are significant contributors to vitamin K intake in the U.S. because they’re used so widely in cooking and processed foods. A tablespoon of soybean oil provides roughly 25 micrograms. Fresh herbs like parsley, basil, and cilantro are also concentrated sources, though you typically eat them in smaller amounts.
Broccoli, Brussels sprouts, cabbage, and green peas all provide meaningful amounts of K1 as well. Even if you’re not eating a big spinach salad every day, a varied diet that includes several green vegetables throughout the week will generally keep your intake on track.
Fermented and Animal Foods for K2
Natto, a traditional Japanese dish made from fermented soybeans, is by far the richest dietary source of vitamin K2. A single serving can contain hundreds of micrograms. Its strong flavor and sticky texture aren’t for everyone, but nutritionally it’s in a class of its own for this vitamin.
Beyond natto, other fermented foods contribute K2 in more modest amounts. Certain aged cheeses contain meaningful levels, and the amount varies depending on the bacterial cultures used in production. Hard, aged varieties tend to have more than soft cheeses. Poultry and pork products also contain a specific form of K2 (MK-4), particularly when the animals’ feed has been supplemented with a vitamin K precursor. Egg yolks and butter contribute small amounts as well.
How Much You Need
The adequate intake for vitamin K is 120 micrograms per day for adult men and 90 micrograms per day for adult women. These numbers are set by the National Institutes of Health and apply to pregnant and lactating women at the same level as their age group. There’s no established upper limit for vitamin K from food, and toxicity from dietary sources hasn’t been reported.
Meeting these targets is straightforward if you eat vegetables regularly. A single cup of raw spinach gets you past the recommendation for women, and a cup of frozen kale nearly doubles it for men. Even people who don’t eat many greens often get some K1 from cooking oils and the small amounts present in a wide range of fruits and vegetables.
Getting the Most From Your Food
Vitamin K is fat-soluble, meaning your body absorbs it best when there’s some dietary fat in the same meal. Sautéing spinach in olive oil, adding avocado to a kale salad, or drizzling dressing on your greens isn’t just tastier. It helps your body actually take up the vitamin K those foods contain. Eating raw greens without any fat source means you’re absorbing less than you could be.
One practical advantage of vitamin K is its stability. Unlike water-soluble vitamins such as vitamin C, vitamin K is not significantly lost during cooking or freezing. Boiling, steaming, roasting, and even canning all preserve K1 content well. That canned spinach figure of 891 micrograms per cup reflects this: the vitamin survives processing, and the concentrated volume of cooked spinach means you’re eating far more leaves per cup than you would raw.
A Note on Blood Thinners
If you take warfarin (a common blood-thinning medication), vitamin K intake matters in a specific way. Warfarin works by blocking vitamin K’s role in producing clotting proteins, so big swings in your vitamin K consumption can make the medication less predictable. The American Heart Association’s guidance is straightforward: you don’t need to avoid vitamin K foods, but you should eat a consistent amount from day to day. Going from zero greens to a huge spinach salad, or vice versa, is what causes problems. Pick a level of intake you can maintain and stick with it so your medication dose stays calibrated.