Vitamin K Deficiency in Adults

Vitamin K represents a group of fat-soluble vitamins that are essential for the process of blood clotting, or coagulation. In fact, vitamin K is named after the German word, "koagulation" and was discovered by a Danish researcher in 1929. Vitamins K1 and K2 are derived from plant and animal sources, respectively, while K3, K4 and K5 are synthetic versions that are added to commercially produced foods. Vitamin K deficiency is more common in children, but can occur in adults under certain circumstances.

Vitamin K Function

Vitamin K is required as a co-factor for an enzyme that catalyzes glutamic acid into gamma-carboxyglutamic acid, which is essential for the coagulation cascade to occur. Coagulation is a process of stopping blood flow by forming clots, which is critical for healing injuries. Vitamin K deficiency leads to uncontrollable bleeding, and clinically resembles the genetic disease hemophilia. People at risk of forming clots, which could block arteries and cause strokes, are often given anticoagulants that block the actions of vitamin K, which also plays a role in bone mineralization, which facilitates normal bone growth and development.

Adequate Intake Levels

The Food and Nutrition Board of the Institute of Medicine established the adequate intake level for vitamin K in 2001 based on consumption levels of healthy individuals. For adult males of all ages, the adequate intake level for vitamin K is 120 mcg daily. For adult females, including those pregnant and breast feeding, the recommended daily intake is 90 mcg.

Deficiency in Adults

Vitamin K deficiency is considered rare in healthy adults, mainly because it's widespread in foods, the body conserves and recycles it, and bacteria of the large intestine produce the K2 variety. Adults primarily at risk of vitamin K deficiency include those who take anticoagulant drugs, those with liver conditions and individuals with fat absorption problems. In practical terms, people suffering from alcoholism, cystic fibrosis, bulimia and inflammatory bowel disease are at significantly increased risk of vitamin K deficiency. The symptoms of vitamin K deficiency include increased clotting time, excessive bruising, nosebleeds, bleeding gums, blood in urine and feces, anemia and heavy menstruation.

Natural Sources

Vitamin K1 is the main dietary form of the vitamin K group. Rich sources of vitamin K include spinach, kale, broccoli, Brussels sprouts, watercress, Swiss chard, avocado, parsley, kiwifruit and some oils, including soybean, cottonseed, canola and olive. Vitamin K2, which is produced primarily in the large intestine, is also found in meat, eggs and cheeses.

References

• Linus Pauling Institute: Vitamin K Requirements
• "Advanced Nutrition: Macronutrients, Micronutrients and Metabolism"; Carolyn Berdanier; 2009
• "Human Biochemistry and Disease"; Gerald Litwack; 2008
• "American Dietetic Association Complete Food and Nutrition Guide"; American Dietetic Association; 2006