The use of vitamin K supplements was called into question during the 1990s because of a proposed link in newborns given a vitamin K injection at birth and the increased risk of later developing childhood cancer. The controversy has since subsided with the endorsement of the American Academy of Pediatrics indicating that the claims of cancer risk are unfounded. Vitamin K is an essential vitamin that is safe when consumed from natural sources and in most cases not required in supplemental form.
Vitamin K Function
Vitamin K is fat-soluble, it stores in your fat tissue and liver and your body releases it as needed. It is referred to as the coagulation vitamin because the primary purpose of vitamin K is in helping your blood clot. Vitamin K is made up of different compounds, the natural forms include phylloquinone or menaquinones, that are required by your liver to form the proteins that promote coagulation. Without this vitamin, proteins in your blood would not properly clot and hemorrhage can occur. Vitamin K also plays a role in bone mineralization and supporting the nervous system but the exact mechanism of action is not fully understood, notes the Linus Pauling Institute.
Deficiency Risks
Newborns are at increased risk of vitamin K deficiency in utero because this vitamin does not pass the placental barrier and bacteria is not present in the fetus intestines in order to synthesize vitamin K properly. For this reason, newborns are given a one time injection of phylloquinone to prevent the life-threatening bleeding disorder of intracranial hemorrhage. Adults rarely experience vitamin K deficiency because it is widely available from food sources and easily synthesized by your bacteria inhabited colon. Those at increased deficiency risk include individuals on anticoagulant medications, those with liver damage and fat malabsorption disorders.
Adequate Intakes
The Food and Nutrition Board of the Institute of Medicine established adequate intakes for vitamin K based on age and gender. Infants from birth to one year are suggested to get vitamin K from breast milk at 2.0 to 2.5 mcg per day. Children between 1 and 13 years old are suggested to get 30 to 60 mcg from natural food sources. Fourteen to 18-year-old adolescents are recommended to get 75 mcg per day. Male adults need 120 mcg and female adults need 90 mcg of vitamin K per day. No upper limit is set for vitamin K and it is not associated with toxicity when taken in natural forms. The synthetic compound menadione, or vitamin K3, is toxic and is not available for human use.
Sources and Precautions
Vitamin K is abundant in green plant-based foods. One cup of raw spinach has 145 mcg, 1 cup of cooked broccoli contains 220 mcg and the same serving of raw kale has 547 mcg of vitamin K. Canola oil, soybean oil and olive oil at one tablespoon servings have 8.1 to 25.0 mcg of this vitamin. Multivitamin supplements typically include adequate dosing of vitamin K and are generally safe. Vitamin K foods and supplements may interfere with blood thinning medication like coumadin. Antibiotics in the class cephalosporins may inhibit vitamin K absorption when taken for more than 10 days, resulting in possible deficiency.
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