Throughout life, bone is constantly changing, breaking down and being replaced. Bone building slows with age, tipping the balance in favor of bone breakdown and resulting in bone loss that can progress to osteoporosis. A new study found that taking vitamin K–fortified dairy foods prevented bone loss in postmenopausal women.
Green leafy vegetables are a major source of vitamin K1
The study, published in Calcified Tissue International, included 173 healthy postmenopausal women without osteoporosis. They were divided into four groups: the control group ate their usual diet and received no supplements; the other three groups received diet and exercise counseling, and were given milk and yogurt products fortified to provide 800 mg of calcium and 10 mcg (400 IU) of vitamin D3 per day for one year. In addition, 100 mcg of vitamin K1 (phylloquinone) was added to the dairy products of one group and 100 mcg of vitamin K2 (menaquinone-7) was added to the dairy products of another group. Bone density and blood and urine markers of bone turnover (breakdown and repair) were measured at the beginning and end of the study.
Several significant differences between the groups were identified at the end of the study:
“The present study revealed more favorable changes in bone metabolism and bone mass indices for the two vitamin K supplemented groups,” the study’s authors said.
Scientists used to think vitamin K was only important because of its role in blood clotting. Now vitamin K is attributed with heart-protective and bone-preserving actions. The form of vitamin K known as phylloquinone, or K1, is the most abundant form in plants and is believed to play the biggest role in blood clotting; K2 refers to a group of related types of vitamin K known as menaquinones that are thought to be more involved in the other effects of vitamin K.
This study showed that a comprehensive osteoporosis-prevention program is more effective if it includes vitamin K. Here are some ways to increase your intake:
(Calcif Tissue Int 2012;90:251–62)