Vitamin K

Vitamin K is a fat-soluble vitamin, and is naturally made by bacteria in our intestines. It is important for blood clotting, bone health, and for producing proteins needed by our blood, bones, and kidneys.

How much do I need?

  • 90 micrograms per day for adult women
  • 120 micrograms per day for adult men
  • For recommendations for infants, children, and teens, check out the chart in CSU Extension’s fact sheet: Fat-Soluble Vitamins: A, D, E, and K.

Food sources

Vitamin K is found in small amounts in many foods, but is highest in dark leafy greens like kale, spinach, turnip greens, collard greens, and Swiss chard. Each cup of these cooked greens contains 500-1100 micrograms of vitamin K. It is also found in large amounts of some vegetable oils like olive, canola, and soybean oil.

What happens if I don’t get enough?

Excess bleeding can occur with too little vitamin K. Deficiencies are rare in the United States, but are most common with the use of anticoagulants (blood thinners) or antibiotics, and with chronic diarrhea or other health problems that may result in poor absorption of nutrients from food.

Can I get too much?

Vitamin K is fat-soluble, which means it can be stored in the body for long periods of time. Toxicity doesn’t usually occur when vitamin K comes from food, but extra caution should be used with supplements. If you are taking blood thinners, or have a health condition that affects blood clotting, talk to your health care provider about the right amount of vitamin K for you.