K — it’s the text you dread, OR vitamin K — the powerhouse nutrient that helps your body with blood clotting and provides a whole host of other benefits.
It mostly comes from leafy greens and meat, but you can also take it as a supplement.
So, when you’re trying to fuel your body with all the vitamins and minerals it needs, getting a “K” is a great thing. Here’s everything you need to know about this important nutrient.
Fast facts on vitamin K
What is vitamin K?
Vitamin K refers to a whole group of fat-soluble compounds with a similar chemical structure.
What are the benefits of vitamin K?
- Promotes blood clotting
- Improves bone health
- Protects your heart
How much vitamin K do you need per day?
According to the National Institutes of Health, the recommended adequate intake of vitamin K for folks older than 19 is:
- 120 micrograms (mcg) for males
- 90 mcg for females
Vitamin K can be found throughout your body, including your liver, bones, brain, heart, and pancreas.
Vitamin K isn’t a singular nutrient. The term “vitamin K” actually refers to a group of fat-soluble compounds. They’re K vitamins, which means they have a common chemical structure.
Vitamin K1 (phylloquinone) and vitamin K2 (menaquinone) are the most important substances in this group.
Vitamin K1 is created by green plants and algae. A 2015 research review showed that it makes up about 90 percent of the vitamin K you get through your diet.
Even though K1 supplements are absorbed well by your bod, the vitamin K1 naturally found in vegetables isn’t. In fact, a 2012 research review showed that you only absorb about 10 percent of the K1 from plant foods.
But it’s possible to absorb more. K1 is a fat-soluble nutrient, so adding a fat source (like butter or olive oil) to veggie dishes can help.
Vitamin K2 refers to a group of menaquinones that are primarily created by bacteria. Menaquinone-4 (MK-4) and menaquinone-7 (MK-7) are two of the most important types of K2.
You get K2 from animal-based foods and certain fermented foods. The bacteria in your gut can also produce K2.
Your body is better at absorbing some forms of K2 (like MK-4) than others. You can get more MK-4 by eating foods like eggs and meat.
So, exactly what does vitamin K do in your body? It’s involved in some important bodily processes.
1. Promotes blood clotting
Vitamin K activates the enzymes that help with blood clotting. Why’s that important? If your blood doesn’t clot correctly it can increase your risk of experiencing bleeding.
Vitamin K doesn’t get delivered through the placenta very effectively, so newborns are given a vitamin K injection when they’re born. This helps prevent vitamin K deficiency bleeding.
2. Improves bone health
Vitamin K helps keep your bones healthy. Osteocalcin, one of the main proteins found in the bones, needs vitamin K in order to bind to calcium. That’s part of how it builds the bone matrix.
Vitamin K also helps osteoblasts (cells that form new bone) and other proteins involved in bone metabolism.
3. Protects your heart
Vitamin K can help prevent heart conditions. “Bless its heart!”
Matrix Gla protein (MGP) is a protein that stops the calcification of your arteries. If calcium can build up, these important pathways that deliver blood to your heart can narrow. That’s not great for your ticker.
MGP (and its anti-calcification powers) is activated by vitamin K. Without enough vitamin K, MGP can’t perform its job and this may lead to an elevated risk of developing heart conditions.
Vitamin K1 and K2 are found in different types of foods. Vitamin K1 is primarily found in plant foods, while K2 is found in animal-based and fermented foods. This table summarizes how much vitamin K is in certain foods:
|Amount of vitamin K||% Daily Value (DV)|
|3 ounces natto||850 mcg||708%|
|1/2 cup cooked collard greens||530 mcg||442%|
|1 cup raw spinach||145 mcg||121%|
|1 cup raw kale||113 mcg||94%|
|1/2 cup cooked broccoli||110 mcg||92%|
|1/2 cup roasted soybeans||43 mcg||36%|
|1/2 cup canned pumpkin||20 mcg||17%|
|1/2 cup raw okra||16 mcg||13%|
|1 tablespoon Caesar dressing||15 mcg||13%|
|1 ounce pine nuts||15 mcg||13%|
|3 ounces cooked chicken breast||13 mcg||11%|
|1 ounce roasted cashews||10 mcg||8%|
Most people get enough vitamin K through their diet, and true vitamin K deficiency is extremely rare, especially in healthy people.
There are a few populations that commonly experience vitamin K deficiency, including people who:
- live with malabsorption conditions like celiac disease and ulcerative colitis
- had bariatric surgery
- take long-term antibiotics or bile acid sequestrants
- are infants
If you’re in one of these groups, a doctor might suggest supplementing with vitamin K.
Severe vitamin K deficiency can lead to symptoms like increased bleeding (including hemorrhage). Vitamin D deficiency can also increase your risk of developing osteoporosis.
Vitamin K isn’t likely to cause toxicity.
There’s no known toxicity for vitamin K1 or K2 from food or supplements. That’s why there’s no established tolerable upper intake level set for it.
If you’re taking a blood thinning medication (like warfarin), try to keep your vitamin K intake consistent and avoid large quantities of vitamin K-rich foods. Why? Because sudden increases in vitamin K could interact with your medication. That could lead to increased or decreased blood clotting.
Can you take vitamin K supplements every day?
Vitamin K has no known toxicity, so it’s generally safe to take it on a daily basis.
Keep in mind, though, that most people don’t need to supplement with vitamin K at all. The daily recommended amount of vitamin K is pretty easy to get just through the foods that you eat.
If you don’t eat many foods that are high in vitamin K, or if you have questions about your vitamin K levels, ask a doctor for their advice.
Vitamin K refers to a group of fat-soluble nutrients, including K1 and K2.
K1 is primarily found in plant foods like leafy greens, while K2 is concentrated in certain animal products and fermented foods.
Vitamin K supplements are safe and not associated with toxicity or side effects in healthy people. If you take certain medications (like blood thinners), though, be aware of your vitamin K intake and have your levels monitored regularly.
Most people get enough vitamin K through their diet. Vitamin K deficiency is extremely rare, but it can happen if you have certain medical conditions.
If you’re interested in supplementing with vitamin K, talk with a doctor. They can help you decide if it’s necessary and find the right dosage for you.