Vitamin K has one main purpose: it allows your body to form blood clots and prevents you from bleeding to death. Dietary vitamin K, also known as phylloquinone or K-1, is present in kale, cabbage, spinach and other leafy green foods, as well as soybeans, cereals and other veggies. Bacteria that live in your gastrointestinal tract also create a form of vitamin K called K-2, or menaquinone. The Merck Manuals Online Medical Library says that you can consume large amounts of vitamin K-1 without any toxic effects.
Function
Vitamin K is essential in a chemical reaction that allows certain proteins, called coagulation factors, to bind calcium and form blood clots. There are 13 different coagulation factors, and each plays a specific role in a chain of chemical reactions known as the coagulation cascade. If any of these factors are deficient, a blood clot can not set up properly, and bleeding will continue. Vitamin K regulates the production of four of these coagulation factors, and others are dependent on vitamin K in order to function properly. As the coagulation cascade occurs, the vitamin K that aids in the clot formation is changed into a reaction product called vitamin K epoxide. Enzymes then convert this back to active vitamin K, which is then ready for re-use.
Toxicity
A synthetic vitamin K precursor known as menadione, or K-3, can cause overdose and brain damage in infants, according to the Pharmacogenomics Knowledge Base. For that reason, over-the-counter supplements containing menadione have been banned by the Food and Drug Administration. Large doses of menadione can cause allergic reactions, hemolytic anemia and cytotoxicity in liver cells in humans.
Deficiency
Fears about too much vitamin K should not deter you from eating foods that are rich in vitamin K. Leafy green vegetables rich in vitamin K can help prevent you from experiencing the excessive bleeding that can result from lack of sufficient vitamin K. Symptoms such as nosebleeds, bloody gums and blood in your urine and feces can result when you don't have enough vitamin K in your system. However, vitamin K deficiencies are rare in adults. Newborn infants may experience vitamin K deficiencies due to the lack of normal intestinal bacteria that produce vitamin K and the relatively low concentrations of vitamin K found in breast milk.
Dosages
Your need for vitamin K grows as you do. The Linus Pauling Institute states that adequate intake of this nutrient grows from 2 mcg daily in infants below six months of age to 75 mcg for adolescents that are 14 through 18 years of age. Adult males are advised to consume 120 mcg daily, while adult females should consume 90 mcg per day. Consult your doctor if you have concerns about a possible vitamin K deficiency.
Member Comments