Vitamin K is an essential fat-soluble vitamin. It helps synthesize proteins used for bone metabolism, blood clotting, and more. Since it’s fat-soluble, eating it with a source of fat can increase its absorption. You can take vitamin K as a supplement, or you can get it from certain types of food like leafy greens, soy-based foods, herbs, and some fruits.

Most adults consume the recommended daily 90–120 micrograms (mcg) of vitamin K, so deficiency is rare. While it’s generally safe to consume, folks taking blood thinners like Coumadin (warfarin) need to be careful about keeping their vitamin K intake steady throughout the day because of its role in blood clotting.

Leafy greens are some of the best sources of vitamin K. A few of these greens can fulfill your daily need for vitamin K in just one serving. For example, ½ cup of boiled collard greens contains 442% of the daily value (DV) of vitamin K.

Leafy green vegetables are also rich in fiber, antioxidants, iron, magnesium, potassium, and calcium.

Some of the best leafy greens for vitamin K include:

• Collard greens: 530 mcg per 0.5 cups boiled, or 442% of the DV
• Turnip greens: 426 mcg per 0.5 cups boiled, or 355% of the DV
• Spinach: 145 mcg per cup raw, or 121% of the DV
• Kale: 113 mcg per cup raw, or 94% of the DV
• Iceberg lettuce: 14 mcg per cup raw, or 12% of the DV

Cruciferous vegetables are another great way source of vitamin K. They’re also a good source of vitamin C, folic acid, and carotenes. The antioxidants in leafy greens can help reduce inflammation and oxidative stress.

Cruciferous vegetables high in vitamin K include:

• Brussels sprouts: 156 mcg per cup, or 130% of the DV
• Broccoli: 110 mcg per 0.5 cups boiled, or 92% of the DV
• Cabbage: 31.8 mcg per cup raw, or 27% of the DV
• Bok choy: 58 mcg per cup boiled, or 48% of the DV
• Cauliflower: 17 mcg per cup, or 14% of the DV

Eating certain fruits is another way to get vitamin K. Like vegetables, fruits are rich in fiber. They’re a good source of key nutrients like potassium, vitamin C, and folate. Plus, eating fruits and veggies as a part of a well-rounded diet is linked with reduced risk for chronic diseases like diabetes and heart disease. 

Fruits that are good sources of vitamin K include:

• Avocado: 29 mcg per fruit, or 24% of the DV
• Blueberries: 29 mcg per cup, or 24% of the DV
• Grapes: 22 mcg per cup, or 18% of the DV
• Pumpkin: 20 mcg per 0.5 cups canned, or 17% of the DV
• Pomegranate: 23 mcg per 0.5 cups raw, or 19% of the DV

Various soy-based foods can be excellent sources of vitamin K. Foods like roasted soybeans and edamame are also good sources of plant-based protein and fiber for muscle, digestive, metabolic, and heart health.

Some soy foods rich in vitamin K include:

• Natto: 850 mcg per 3 ounces (oz), or 708% of the DV
• Soybeans: 43 mcg per 0.5 cups roasted, or 36% of the DV
• Soybean oil: 25 mcg per tablespoon (tbsp), or 21% of the DV
• Edamame: 21 mcg per 0.5 cups, or 18% of the DV
• Tofu: 7 mcg per 3 oz fried, or 6% of the DV

Herbs offer plenty of flavor to add to your dishes, but they are also nutrient-dense. Herbs are full of antioxidants, and some research shows they may help lower cholesterol and blood sugars and reduce inflammation.

Even small amounts of herbs can be an excellent source of vitamin K. Herbs with the most vitamin K include:

• Thyme: 46 mcg per tbsp dried, or 38% of the DV
• Basil: 35 mcg per tbsp dried, or 29% of the DV
• Sage: 34 mcg per tbsp ground, or 28% of the DV
• Parsley: 22 mcg per tbsp dried, or 18% of the DV
• Marjoram: 11 mcg per tbsp dried, or 9% of the DV

Vitamin K’s two main roles are blood clotting and bone health. The body requires vitamin K to produce proteins known as clotting factors in the liver. Without these, blood would not clot. 

Vitamin K is also required to produce key proteins for bone metabolism. As a result, low vitamin K intake is linked to an increased risk of bone fracture. Some studies have found that taking a vitamin K supplement may help lower fracture risk, but more high-quality studies are necessary to confirm this benefit.

For most people, eating a variety of vitamin K-rich foods is enough to maintain adequate vitamin K levels. Many of these foods are full of other health-promoting nutrients like fiber, protein, and antioxidants. Plus, supplementing with vitamin K may be costly and inconvenient.

Most people get enough vitamin K from their diet, so deficiency isn’t common. If a deficiency does happen, it’s usually caused by a malabsorption disorder like cystic fibrosis (CF), celiac disease, or ulcerative colitis (UC). A deficiency may also be caused by long-term use of antibiotics, but maintaining adequate dietary vitamin K intake usually prevents a deficiency in this case.

In severe cases, a vitamin K deficiency can cause bleeding and hemorrhage, but this is very rare. It may also lower bone mass and ultimately lead to osteoporosis (bone thinning and weakening).

If you think you are at risk of vitamin K deficiency, speak with your healthcare provider. They can test you for vitamin deficiencies and, if you are deficient, may administer vitamin K intravenously. They can offer suggestions for increasing your vitamin K intake through food and supplements. Your provider can also help address the underlying cause of the deficiency, like a malabsorption issue or antibiotic use.

Although most fat-soluble vitamins have upper limits set to prevent excess buildup in your body, there isn’t an upper limit set for vitamin K because of its low potential for toxicity.

However, vitamin K can interact with the blood-thinning medication Coumadin (warfarin), so it’s important to maintain a consistent vitamin K intake if you’re taking this drug. Since vitamin K affects blood clotting, altering your daily vitamin K intake can cause potentially dangerous drug-nutrient interactions.

Vitamin K may also interact with antibiotics and bile acid sequestrants like Prevalite (cholestyramine) and Xenical (orlistat). If you’re taking one of these medications, consult with a healthcare provider before supplementing with vitamin K.

There have been some cases of intravenous (IV) administration of vitamin K causing bronchospasm (muscular tightening of the lungs) and cardiac arrest. However, taking vitamin K as an oral supplement isn’t associated with adverse effects, and supplementing with vitamin K is generally safe.

Most people get enough vitamin K through dietary sources, so supplementation may be unnecessary.

Vitamin K is a fat-soluble vitamin essential for blood clotting and bone health. To meet your vitamin K needs through food, incorporate leafy greens, cruciferous vegetables, soy foods, certain fruits, and herbs into your diet.

Many of these foods are excellent sources of vitamin K, as well as antioxidants, plant-based protein, fiber, and other vitamins.