You get vitamin K2 primarily from animal-based foods, fermented foods, and supplements. Your body also produces some on its own through gut bacteria and by converting vitamin K1 from leafy greens. Unlike vitamin K1, which is abundant in vegetables like spinach and kale, K2 is found in a narrower range of foods, and most Western diets tend to be low in it.
Best Food Sources of Vitamin K2
The richest food sources of K2 fall into two categories: animal products and fermented foods. Each delivers different forms of the vitamin. Animal foods provide a form called MK-4, while fermented foods supply longer-chain forms like MK-7, MK-8, and MK-9.
Among animal foods, the top sources include:
- Chicken liver and other organ meats: These contain the highest concentrations of K2 among common animal products, along with iron and B vitamins.
- Chicken breast and dark meat poultry: A practical everyday source, since poultry fits easily into most meals.
- Egg yolks: A meaningful source of K2, though the amount varies depending on what the hens were fed. Pasture-raised eggs tend to contain more.
- Hard and semi-hard cheeses: Gouda, Emmental, Brie, and Edam all contain K2 produced by the bacteria used during fermentation. A Swiss study analyzing 121 cheese samples found K2 content ranged widely, from 23 to 1,312 micrograms per kilogram, depending on the type and the bacterial cultures used in production.
Natto, a Japanese dish made from fermented soybeans, is often cited as the single richest source of K2, specifically the MK-7 form. It has a strong flavor and sticky texture that many people outside Japan find challenging, but even small servings deliver substantial amounts. Other fermented foods like sauerkraut and kefir contain some K2, though in much smaller quantities.
Why Cheese Varies So Much
Not all cheeses are equal when it comes to K2. The type and amount depend almost entirely on which bacteria are involved in the fermentation process. Emmental cheese gets its K2 from a specific group of bacteria (Propionibacterium) that produces one particular form. Semi-hard and soft cheeses made with different starter cultures produce a broader mix of K2 forms. Interestingly, factors you might expect to matter, like fat content, water content, and how long the cheese was aged, don’t reliably predict K2 levels. The bacterial culture is what drives the difference.
K2 Your Body Makes on Its Own
Your gut bacteria produce several forms of vitamin K2 as a byproduct of their normal metabolism. Different species make different forms: E. coli produces MK-8, Bacteroides species produce MK-10 and MK-11, and Veillonella produces MK-7. This internal production may cover anywhere from 10 to 50 percent of your total vitamin K needs, though researchers still aren’t sure of the exact contribution because much of this K2 is produced deep in the colon where absorption is limited.
Your body also converts some vitamin K1 into K2. When you eat leafy greens, the K1 gets broken down in your intestine into a simpler intermediate compound, which then travels through your bloodstream and gets reassembled into the MK-4 form of K2 in various tissues, including your brain. This conversion happens, but it’s not efficient enough to fully replace dietary K2.
MK-4 vs. MK-7 Supplements
If your diet doesn’t include many of the foods listed above, supplements are a straightforward option. The two main forms sold are MK-4 and MK-7, and they behave differently in your body.
MK-7 stays in your bloodstream much longer than MK-4, which means a single daily dose maintains more consistent levels. MK-4 clears the body quickly and typically requires higher doses to achieve the same effect. Most supplement manufacturers favor MK-7 for this reason, and it tends to be more practical from both a dosing and cost perspective. That said, some bone health research has used very high doses of MK-4 (45 mg) and found benefits, while the evidence for MK-7’s effects on bone is still developing. Many supplements now combine both forms.
Most MK-7 supplements are produced through bacterial fermentation, often using the same species of bacteria (Bacillus subtilis) that ferments natto. This makes them suitable for people who want the benefits of natto without eating it.
How Much You Need
There is no official recommended intake specifically for K2. Government guidelines set an “adequate intake” for total vitamin K (K1 and K2 combined) at 120 mcg per day for adult men and 90 mcg for adult women. These numbers are based on what healthy populations typically consume, not on precise measurements of what’s optimal, because the research isn’t far enough along to set a firm requirement.
In practice, most people meet their total vitamin K needs through K1 from vegetables. The question with K2 is whether the additional benefits for bone and cardiovascular health justify seeking it out specifically. Many nutrition researchers think they do, even though the official guidelines haven’t caught up.
Getting the Most From K2
Vitamin K2 is fat-soluble, which means your body absorbs it best when you eat it alongside dietary fat. This is rarely a problem in practice, since most K2-rich foods already contain fat: cheese, egg yolks, dark meat poultry, and liver all come with built-in fat. If you’re taking a supplement, having it with a meal that includes some fat (a handful of nuts, olive oil on a salad, or any cooked dish with oil or butter) will improve absorption compared to taking it on an empty stomach.
For most people, the simplest strategy is eating a few eggs a week, choosing cheeses like Gouda or Emmental when you have the option, and including poultry or organ meats regularly. If those foods aren’t part of your diet, a daily MK-7 supplement taken with a meal covers the gap reliably.