Vitamin K, also called phylloquinone, is a fat-soluble nutrient that plays a vital role in sustaining health and preventing disease. Vitamin K is found in nutrient-dense foods, including vegetables you can eat raw or cooked. The bioavailability of vitamin K differs between raw and cooked versions of the same vegetable. However, you do not have to cook vegetables to obtain sufficient amounts of vitamin K. Consult your nutritionist about vitamin K in vegetables.
Vitamin K Requirements
The recommended dietary intake per day of vitamin K is 90 micrograms for women and 120 micrograms for men ages 19 years and older. Nonetheless, vitamin K deficiency in adults is rare, primarily because the nutrient is found in many foods, and certain bacteria in your large intestine synthesize the vitamin. However, you can become deficient in vitamin K if you take anti-coagulant drugs, also called blood thinners, such as warfarin, or have liver disease or fat malabsorption.
Vegetable Sources
Vitamin K is found in dark green leafy vegetables that include spinach, cabbage, Swiss chard, Brussels sprouts, kale, Romaine lettuce, collard greens and bok choy. In addition to vitamin K, these nutrient-dense vegetables contain minerals, vitamins and antioxidants. Plus vegetables are good sources of soluble fiber and insoluble fiber, indigestible substances that reduce absorption of dietary cholesterol and add bulk to speed up excretion of waste.
Bioavailability
Vitamin K is available from both raw and cooked raw green leafy vegetables. However, the available amount of vitamin K for absorption into your body is higher from cooked vegetables than raw vegetables. A 1-cup serving of boiled chopped kale that is drained without salt contains 1,062.1 micrograms of vitamin K, whereas a 1-cup serving of raw chopped kale contains 547.4 micrograms. A 1-cup serving of boiled spinach that is drained without salt contains 888.5 micrograms of vitamin K, whereas a 1-cup serving of raw spinach contains 144.9 micrograms. A 1-cup serving of boiled Brussels sprouts that is drained without salt contains 218.8 micrograms of vitamin K, whereas a 1-cup serving of raw Brussels sprouts contains 155.8 micrograms.
Function
Vitamin K has two primary functions in the human body. Vitamin K helps you stop bleeding after an injury or surgery. People with a risk of blood clots who take anti-coagulants must limit the amount of vitamin K in the diet because the nutrient interferes with the drug. The second function of vitamin K is to promote bone mineralization.
References
- Colorado State University; Fat-Soluble Vitamins; 2010
- United States Department of Agriculture; Vitamin K: Another Reason to Eat Your Greens; January 2000
- Linus Pauling Institute at Oregon State University; Vitamin K; Sarah Booth; May 2008
- United States Department of Agriculture; National Nutrient Database for Standard Reference, Release 23; September 2010
- MayoClinic.com; Dietary Fiber: Essential for a Healthy Diet; 2009
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