Here’s everything you need to know about this important nutrient.
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.
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 created by bacteria. Menaquinone-4 (MK-4) and menaquinone-7 (MK-7) are two of the most important types of K2.
Vitamin K is involved in some important bodily processes.
1. Promotes blood clotting
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 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.
These foods are rich in vitamin K1:
- kale (145 μg/100 g)
- brussels sprouts (177 μg/100 g)
- broccoli (180 μg/100 g)
- spinach (380 μg/100 g)
- sauerkraut (22.4 μg/100 g)
- collards (706 μg/100 g)
- roasted soybeans (57.3 μg/100 g)
- kiwi (33.9 to 50.3 μg/100 g)
These foods have lots of vitamin K2:
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 fall into one of these groups, a doctor might suggest supplementing with vitamin K.
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.
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.