Green leafy vegetables are the richest sources of vitamin K. The highest sources include parsley, kale and Swiss chard. One cup of raw parsley contains 984 micrograms of vitamin K; a cup of raw kale contains 472 micrograms; and 1 cup of raw Swiss chard contains 299 micrograms. Other excellent green leafy sources of vitamin K include spinach, collard greens, turnip greens and mustard greens.
Green leafy vegetables are not the only good sources of vitamin K. One cup of raw brussels sprouts contains about 156 micrograms of the vitamin; 1 cup of raw broccoli contains about 93 micrograms; and 1 cup of raw cabbage contains about 67 micrograms. Other good vegetable sources include asparagus, cauliflower, celery and leeks.
The Food and Nutrition Board at the Institute of Medicine set an adequate intake level for vitamin K based on the average intake of healthy individuals. The adequate intake level set for adults aged 19 years and older is 90 micrograms per day. Vitamin K deficiency is rare; however, it can occur in people with disease that may affect the absorption of vitamin K or in people on long-term antibiotic therapy. Symptoms of a vitamin K deficiency include easy bruising and bleeding that may occur as nose bleeds, bleeding gums, excessive menstrual bleeding or blood in the urine.
A tolerable upper level for vitamin K has not been established, as there are currently no known toxicities or adverse effects related to the intake of high amounts of vitamin K from foods or supplements. However, vitamin K can affect how certain blood-thinning medications work; therefore, vitamin K foods may need to be limited when taking these medications.