Parsley, chard, kale, watercress and spinach contain the highest levels of vitamin K per 200 calorie serving of vegetables. Mustard, turnip, beet and collard greens contain significant amounts as well. Vitamin K plays a crucial role in the body's ability to effectively form blood clots.
Most people receive adequate vitamin K intake in their daily diet, according to WebMD. The recommended daily allowance of vitamin K ranges from 2 to 120 micrograms based on age and sex. Certain medications, including blood thinners, aspirin and antibiotics, interfere with the effects of vitamin K in the body. Some medical conditions, such as Crohn's and celiac disease, adversely affect the body's ability to absorb the nutrients consumed.