Vitamin K: Everything You May Need to Know

Vitamin K is a group of vitamins that share similar chemical structures. Two different forms of vitamin K are most commonly found in the human diet.

Vitamin K1, the predominant dietary form of vitamin K, is also known as phylloquinone. You can find it in plant foods such as leafy greens. Vitamin K2 — also called menaquinone — is found in some animal products and fermented foods. Your gut bacteria also produce it.

The body absorbs vitamin K1 and K2 at different rates, which can affect the health benefits they each offer. More research is still needed, but you can learn more about vitamin K1 and K2 here.

One other important thing to note is that vitamin K is a fat-soluble vitamin, so when you consume extra quantities it is stored in the liver and other body tissues.

Vitamin K and potassium are both essential nutrients and help in many of the same body functions. But vitamin K and potassium aren’t the same thing.

Potassium is a mineral with its own unique chemical composition, not a vitamin. It functions as an electrolyte helping the body maintain a proper water balance and blood pressure.

While the body can produce small amounts of vitamin K, you have to obtain all of the body’s potassium from foods and supplements. You can read more about the differences between vitamin K and potassium here.

Vitamin K is essential in supporting blood clotting. It also plays an important role in bone and heart health. People who are deficient in vitamin K are at increased risk of developing osteoporosis and heart disease.

Between 8–31% of people have vitamin K deficiency.

Serious vitamin K deficiency is rare, but symptoms can include:

• hemorrhaging or uncontrolled bleeding
• bruising
• nosebleeds
• dark stools with blood in them
• small bruises under the fingernails

Those at a higher risk of vitamin K deficiency include:

• newborns who haven’t received a vitamin K injection
• people with conditions such as celiac disease, ulcerative colitis, and short bowel syndrome that affect the amount of nutrients absorbed
• those who have had weight loss surgery

Foods that contain vitamin K include:

• leafy greens (ex. kale, spinach, lettuce)
• Brussel sprouts
• broccoli
• cauliflower
• vegetable oils
• blueberries
• figs
• eggs

Most people can get enough vitamin K through a balanced diet, making vitamin K supplements unnecessary. Also, the liver stores extra vitamin K, which can eliminate the need for daily consumption.

Vitamin K supplements can be an effective way to increase levels of this essential nutrient in the body if health conditions or medications prevent sufficient absorption through food consumption.

Current research is insufficient to prove serious complications from consuming too much vitamin K.

But certain medications can affect vitamin K needs including:

• blood thinners such as Warfarin
• antibiotics
• bile acid sequestrants such as cholestyramine and colestipol, which are used to lower cholesterol levels
• weight loss drugs such as Orlistat

If you’re taking any medications, it’s important to talk with your doctor about how they may affect your nutrient needs.

Vitamin K is an essential nutrient necessary for blood clotting and bone health.

While the body can produce a small amount of this essential nutrient, you should consume the majority of it through foods such as leafy greens and vegetable oils.

Although vitamin K deficiency is rare, you may experience bruising problems and increased bleeding if you don’t consume enough. Your doctor can advise you whether vitamin K supplements would be beneficial.