Vitamin K is a fat-soluble vitamin. Fat-soluble vitamins are stored in the body in the liver and fatty tissues. Unlike the other fat-soluble vitamins, the body actually stores very little vitamin K. This makes regular dietary intake important. Bacteria in the large intestines help by making a range of vitamin K forms called menaquinones. Vitamin K is also produced by plants (phylloquinone) and is primarily found in green vegetables (collards, spinach, salad green, broccoli), brussels sprouts, cabbage, and plant oils. The man-made vitamin K found in supplements is called menadione.

Functions

Vitamin K’s functions include:

• Playing an essential role in the blood-clotting process by making the proteins that stop bleeding
• Helping your body make other proteins essential for blood, bones, and kidneys

Recommended Intake:

Vitamin K Deficiency

If you do not get enough vitamin K, your blood will not clot normally. Among healthy people, a deficiency is rare. Symptoms of vitamin K deficiency include:

• Easy bruising and bleeding ( nosebleeds, bleeding gums, blood in the urine, blood in the stool, or extremely heavy menstrual bleeding)
• Bleeding in the skull (intracranial hemorrhage) in infants

Vitamin K Toxicity

As a fat-soluble vitamin, vitamin K is stored in the body and not excreted in the urine, like most water-soluble vitamins. While allergic reactions could happen, no symptoms have been observed among people consuming excess amounts of the natural-form of vitamin K. There have been some problems associated with the man-made form of the vitamin (menadione), though. Some infants who were given injections of menadione had liver toxicity, jaundice, and rupture of the blood cells. No tolerable upper intake level (UL)—that is, the highest amount healthy people can consume without endangering their health—has been established for vitamin K. But, to be safe, you should follow the intake guidelines based on your age and gender.

Major Food Sources

Health Implications

Tips For Increasing Your Vitamin K Intake

• Slice an avocado. Add a little balsamic vinegar and pepper, and scoop out for a snack. Or, mash the avocado and mix with chopped tomatoes and red onions for a refreshing salsa.
• Pack a kiwi and spoon in your lunch for an afternoon snack. The insides of the kiwi can be scooped out and eaten from this natural and easy container.
• Steam ½ cup broccoli or Brussels sprouts, add lemon juice (1 tbsp), pre-chopped garlic (1 tsp), and Dijon mustard (1 tbsp). Or add broccoli to your favorite lasagna or hot dish.
• Mix 2 (10-ounce) packages of frozen chopped spinach, thawed, well drained, 1 8-ounce package of softened low-fat cream cheese, ¼ cup milk, and 1 teaspoon lemon pepper until well-blended. Spoon into a 1-quart casserole dish and sprinkle with 1/3 cup crushed crackers or seasoned croutons. Bake at 350°F (177ºC) until thoroughly heated (about 25-30 min.).

Abbreviations: mcg = microgram; tbsp = tablespoon; tsp = teaspoon