Vitamin K benefits the bones of both elderly men and women

May 16, 2011

The bone benefits of a diet rich in vitamin K extends to both elderly men and women, according to findings from a new study from Spain. Data from 200 elderly people showed that high dietary intakes of vitamin K were associated with higher measures of bone mineral density (BMD), and higher scores in an ultrasound test, say findings published in the journal Bone.

“The results of the present study showed, for the first time, a direct association between dietary vitamin K intake and calcaneous quantitative ultrasound measurements, suggesting that vitamin K has a direct role in qualitative bone features along with bone mineral density, in a cohort of elderly Caucasian subjects with healthy dietary habits,” wrote the researchers, led by Dr. Monica Bullo from the Human Nutrition Unit at the Universitat Rovira i Virgili in Reus, Spain.

The new Spanish study did not differentiate between the various forms of vitamin K, but looked at overall vitamin K intakes from dietary sources, including greens, dairy, and meat. A cross-sectional analysis was performed with 200 elderly people with an average age of 67 who completed a 137-item food frequency questionnaire (FFQ) and were followed for two years. The researchers used the USDA’s database to estimate vitamin K intakes, and the average intake was calculated to be 334 micrograms per day for men and 300 micrograms per day for women.

Various measures of bone health, including bone mineral density (BMD), were performed using quantitative ultrasound assessment (QUS) in 125 subjects. When comparing vitamin K intakes, the researchers report that for every 100 microgram increase in vitamin K intake there was a 0.008 g/m2 increase in BMD. High dietary vitamin K intake was associated with superior bone properties. Moreover, an increase in dietary vitamin K was significantly related to lower losses of bone mineral density and smaller increases in the porosity and elasticity attributed to aging, which helps to explain the previously described protective effect of vitamin K intake against osteoporotic fractures.

There is biological plausibility for the potential bone health benefits of vitamin K. Osteocalcin is a vitamin K-dependent protein and is essential for the body to utilise calcium in bone tissue. Without adequate vitamin K, the osteocalcin remains inactive, and thus not effective. The study is published online ahead of print in the March 2011 issue of the journal Bone.