You can get vitamin K naturally from two main categories of food: leafy green vegetables for vitamin K1, and fermented foods plus animal products for vitamin K2. Most people easily meet the daily recommended intake of 90 mcg for women and 120 mcg for men through a normal diet that includes vegetables. A single serving of spinach or kale delivers several times that amount.
What makes this nutrient interesting is that K1 and K2 aren’t interchangeable. They come from different foods, travel to different parts of your body, and do different jobs once they arrive.
K1 vs. K2: Why Both Matter
Vitamin K1 (found in plants) heads straight to your liver, where it activates proteins that control blood clotting. Without enough K1, your blood can’t form clots properly, which is why the vitamin was originally named after the German word “Koagulation.” This is the form most people think of when they hear “vitamin K.”
Vitamin K2 (found in fermented and animal foods) behaves differently. After absorption, it circulates beyond the liver to reach your bones and blood vessels. There, it activates proteins that pull calcium into bone tissue and keep it out of your arteries. Studies in people over 50 have shown that adequate K2 improves bone quality and reduces fracture risk. It also activates a protein in blood vessel walls that prevents calcium from building up where it shouldn’t.
Both forms work by activating the same type of specialized proteins, but because they’re distributed to different tissues, getting both through your diet covers the full range of what vitamin K does in your body.
Best Plant Sources of Vitamin K1
Dark leafy greens are by far the richest natural sources. Cooked spinach contains roughly 525 mcg per 100 grams, which is nearly six times the daily intake for women in a single serving. Raw spinach still delivers about 380 mcg per 100 grams. Broccoli provides around 102 mcg per 100 grams. Other top sources include collard greens, kale, Swiss chard, turnip greens, and Brussels sprouts.
Beyond the standout greens, you’ll find meaningful amounts of K1 in:
- Herbs: Parsley, cilantro, and basil are surprisingly concentrated sources, though you typically eat them in smaller quantities.
- Lettuce: Even romaine and green leaf lettuce contribute moderate amounts, making a daily salad habit a reliable way to maintain intake.
- Vegetable oils: Soybean oil and canola oil contain K1, so cooking with these adds small but consistent amounts to your diet.
The takeaway is simple: if you eat a cup of cooked greens a few times a week, you’re almost certainly getting enough K1. The real gap for most people is K2.
Best Food Sources of Vitamin K2
Vitamin K2 comes from two places: bacteria that produce it during fermentation, and animals that accumulate it in their tissues. The richest source in any diet is natto, a Japanese fermented soybean dish. Natto contains dramatically more K2 than any other food, which is one reason researchers have linked traditional Japanese diets to lower fracture rates.
If natto isn’t your thing (its slimy texture and strong smell are polarizing), other fermented and animal foods provide K2 in smaller but still useful amounts:
- Cheese: Aged and fermented varieties like Gouda, Brie, Camembert, Munster, and cheddar all contain K2, though the amounts are modest. Cheddar, for instance, provides only about 0.42 mcg per 30-gram serving.
- Egg yolks: A regular part of many diets and a consistent, if small, source of K2.
- Liver: Chicken and goose liver are among the more concentrated animal sources.
- Chicken and other dark meat: These contain K2 because the animals convert K1 from their feed into K2 in their tissues.
The gap between natto and everything else is large enough that people who don’t eat natto regularly may struggle to get significant K2 from food alone. Eating a variety of cheese, eggs, and meat helps, but none of these foods are K2 powerhouses the way spinach is a K1 powerhouse.
Your Gut Bacteria Make Some K2
Your body has a backup source: the bacteria living in your colon actually produce vitamin K2 on their own. The main producers are E. coli and species from the Bacteroides genus, which are among the most common residents of the adult gut. In infants, these early colonizers appear to be especially active K2 producers.
However, most of this bacterial K2 is produced in the large intestine, where absorption is limited compared to the small intestine. Researchers still debate exactly how much of this internally produced K2 makes it into your bloodstream in usable amounts. It likely contributes something, but not enough to rely on as your primary source. A healthy, diverse gut microbiome supports this production, while antibiotic use can temporarily reduce it.
How to Absorb More From the Foods You Eat
Both forms of vitamin K are fat-soluble, meaning your body absorbs them through the same pathway it uses for dietary fats. Eating vitamin K-rich foods without any fat in the meal significantly reduces how much you actually take in. This matters most for raw salads: a plain spinach salad with fat-free dressing won’t deliver nearly as much vitamin K as the same salad with olive oil, avocado, nuts, or cheese.
Cooking greens also changes the equation. Heat breaks down plant cell walls and concentrates the vitamin (cooked spinach has more K1 per 100 grams than raw), and cooked vegetables are often served with butter or oil, which further improves absorption. Sautéing greens in olive oil is one of the most efficient ways to get vitamin K from food.
K2 absorption is less of a concern because the foods that contain it (cheese, eggs, meat) already come with built-in fat.
How Vitamin K Works With Vitamin D
Vitamin D increases how much calcium your intestines absorb from food. Vitamin K2 then directs where that calcium goes, activating proteins that deposit it into bones and other proteins that prevent it from accumulating in arteries. These two vitamins form a partnership: D gets calcium into your bloodstream, and K2 makes sure it ends up in the right place.
When vitamin D levels are high but vitamin K is low, the proteins responsible for routing calcium can’t function properly. In animal studies, vitamin K deficiency combined with high vitamin D accelerated arterial calcification. This doesn’t mean vitamin D is dangerous, but it does mean that boosting your vitamin D intake (through sunlight, food, or supplements) works best when your vitamin K intake is also adequate. Eating greens and fermented foods covers this naturally.
Keeping Intake Consistent on Blood Thinners
If you take warfarin or a similar blood-thinning medication, vitamin K has a direct effect on how well the drug works. Warfarin functions by blocking vitamin K’s role in producing clotting factors. A sudden increase in vitamin K from food can reduce the drug’s effectiveness, while a sudden decrease can make it too strong.
The key recommendation is consistency, not avoidance. You don’t need to stop eating greens. Instead, keep your dietary pattern roughly the same from week to week and let your doctor know about any planned changes in diet or supplement use. Stable intake allows your medication dose to be calibrated accurately. If your blood-clotting levels fluctuate for no clear reason, some clinicians will suggest a small daily vitamin K supplement to create a more predictable baseline.
Putting It All Together
Meeting your vitamin K1 needs is straightforward: eat green vegetables regularly. A cup of cooked spinach, a serving of broccoli, or a green salad with oil-based dressing a few times a week provides far more than the daily recommendation. For K2, the path requires a bit more intention. Include fermented foods like aged cheese or natto, along with eggs and poultry, as regular parts of your diet. Pair all of these with some dietary fat to maximize absorption, and you’ll cover both forms of this essential nutrient without any supplements.