Vitamin K is routinely administered at birth in the United States, to prevent vitamin K deficiency bleeding (VKDB) in infants up to 6 months old (1). While coagulation is what this vitamin is most known for it also plays an active role in bone and vascular health.
Defining Vitamin K
Vitamin K is the name used to refer to a group of molecules with a similar chemical structure. This includes vitamin K-1 (phylloquinone) and vitamin k-2 (menaquinones). K-1 is found in leafy vegetables and many other plant products, while K-2 can be found in fermented foods and animal products.
We get the majority of our vitamin K-1 by consuming plant products. K-2, however, can be synthesized by microbes in the gut- a reason why probiotics promote K-2 and antibiotics oppose it.
Vitamin K is fat-soluble and can be stored in the liver and fat tissue- but only in small amounts. For this reason, it is necessary to maintain healthy levels of this vitamin through diet.
Roles in the Body
Blood Coagulation (clotting)- Vitamin K is a cofactor that helps activate many proteins involved in the coagulation of blood. This prevents an individual from bleeding out internally and helps repair damaged blood vessels in a process known as hemostasis.
Injection at Birth- A vitamin K shot is commonly given at birth to prevent hemorrhages (bleeding) in the newborn. The low vitamin K in the newborn is partly due to limited movement of vitamin K through the placenta and minute amounts in breastmilk. Furthermore, a newborn’s gut microbes aren’t developed enough to produce K-2 on the own.
Bone Health- Vitamin K seems to promote bone density in individuals with osteoarthritis and lower the incidence of bone fractures. This is partly due to vitamin k’s activation (gamma-carboxylation) of the protein osteocalcin, which is involved in the mineralization of bone. Research suggests that it might also work with vitamin D to promote bone density.
Vascular Health- Growing research suggests that vitamin k has a role in protecting blood vessels. It does so by limiting calcium deposition in the vascular lining- a contributing factor to atherosclerosis. Atherosclerosis is the process by which a plaque forms in an artery wall limiting blood flow and contributing to ischemia. It is a major risk factor for cardiovascular disease (CVD).
Vitamin K Deficiency
Deficiency is not very common although it can happen. Low vitamin K can predispose an individual to major bleeding, fractures, and atherosclerotic plaques. Symptoms may include bloody gums, easy bruising, and nosebleeds. An individual with a balanced diet, however, should not worry much about this deficiency.
Should I Supplement?
Unless recommended by a doctor or dietitian, avoid supplementing on vitamin k. There are plenty of food sources that provide this vitamin and its deficiency is already unlikely. Excess vitamin k may interfere with other medications -like blood thinners- which will only complicate things. It best to eat a well-balanced diet and to consult a professional when in doubt.
References-
- “Vitamin K Deficiency Bleeding.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 31 Mar. 2014, www.cdc.gov/ncbddd/vitamink/faqs.html.
- Weber, P. “Vitamin K and Bone Health.” PubMed, NCBI, Dec. 2001, www.ncbi.nlm.nih.gov/pubmed/11684396.