Post Menopausal? Vitamin K Key for Healthy Bones
A review by Japanese scientists shows that supplements of vitamin K can reduce the risk of fractures in post-menopausal women.
The review was published in the May 2009 issue of the journal Nutrition Research.
There are two main forms of vitamin K: phylloquinone (K1) and menaquinone (K2). Vitamin K1 is the form found in foods like lettuce, broccoli and spinach and it makes up about 90 percent of the vitamin K consumption in a western diet.
Vitamin K2 is more difficult to come by. It is most common in fermented foods such as cheese but can also be found in meat, green leafy vegetables and milk products. It needs to be synthesized by intestinal bacteria before your body can use it. As a result, antibiotics - which kill both good and bad bacteria in the digestive tract - have been shown to reduce vitamin K2 absorption.
Japanese scientists from Keio University School of Medicine in Tokyo analyzed 7 randomized clinical trials for the review.
The clinical trials all sought to investigate the relationship between vitamin K1 and K2 and bone health in post-menopausal women.
The trials involved at least 50 subjects and vitamin K1 doses ranged from 200 micrograms to 5 milligrams per day. The vitamin K2 doses in the study were all at least 45 milligrams per day.
According to the researchers, the data showed that both forms of the vitamin are effective in reducing the risk of bone fracture for post-menopausal women.
The researchers note that the most important finding of the review was the fact that while supplementation with lower doses of vitamin K may be sufficient to reduce fracture risk, supplementation with higher doses may be necessary for optimal bone strength.
Further studies will be necessary to determine both the mechanisms behind these bone health benefits as well as the optimum dosage of vitamin K for post-menopausal women.
Beyond the growing body of research backing vitamin K for bone health, other studies have shown that the vitamin may be essential for cell growth, joint health, heart health, and disease prevention.