Vitamin K & Bone Metabolism

Vitamin K is a fat-soluble vitamin your body needs primarily for normal blood clotting; however, it's also necessary for bone metabolism, and you need adequate amounts to keep your bones strong as you age. Vitamin K is synthesized by probiotic bacteria in your digestive tract, and it's found in foods of both plant and animal origin.

Bone Metabolism

Vitamin K is necessary for the synthesis of proteins called osteocalcin, matrix GIa protein and protein S. All have roles in bone metabolism. Osteocalcium and matrix GIa are necessary for mineralization of the bone matrix and normal bone growth. The role of protein S is not clear; however, according to the Linus Pauling Institute, children who suffer from an inherited protein S deficiency have problems with blood clotting and decreased bone density.

Vitamin K

Two forms of vitamin K appear in nature: phylloquinone, or vitamin K1; and menaquinone, or vitamin K2. Plants synthesize phylloquinone -- it's the form of vitamin K you get when you eat spinach, green vegetables and vegetable oils. Menaquinone is the form made by animals and is the type of vitamin K made by the bacteria in your digestive system. Meat, fish and fermented foods contain small amounts menaquinone.

Adequate Intake

The Food and Nutrition Board of the Institute of Medicine determined the adequate intake of vitamin K for all age groups. Infants ages 7 to 12 months need 2.5 mcg per day. Children need 30 mcg per day from age 1 to 3, 55 mcg per day from age 4 to 8, and 60 mcg from age 9 to 13. Teens need 75 mcg per day. Adult males need 120 mcg per day, while adult females need 90 mcg per day.

Vitamin K Supplements

According to the Linus Pauling Institute, vitamin K in very large doses appears to decrease the rate of bone loss in people with osteoporosis. It also increases bone density and may reduce the risk of bone fractures. Dietary levels of vitamin K may not have as strong an impact on bone health. Vitamin K is available in supplemental form; however, they can interact with certain medications, so speak to your doctor before taking vitamin K supplements.