Vitamin K?s main function is to help blot clot, according to WebMD. The vitamin may also help with osteoporosis, but the evidence is conflicting. Although vitamin K is an essential nutrient, most people receive enough vitamin K from their diets.
Vegetables, such as kale, spinach, cauliflower and cabbage, supply vitamin K, according to MedlinePlus. Vitamin K can also be found in fish, liver and eggs. The bacteria in the gastrointestinal tract synthesize vitamin K as well.
Those at risk of a vitamin K deficiency include newborns and people who drink heavily, according to WebMD. In addition, celiac disease and other diseases that affect the digestive tract may interfere with vitamin K absorption, causing a deficiency.