18 Jun New study seeks to clarify link between vitamin K and mobility
Older adults with insufficient vitamin K are likely to be at higher risk for mobility disability,
according to new research.
Dietary sources of vitamin K include spinach, broccoli, and other leafy greens. Some dairy foods
also, contain vitamin K.
The investigators who carried out the study say that their findings suggest vitamin K may be
involved in the disablement process in older age." They describe their work in a paper that
features in a recent issue of The Journals of Gerontology: Series A.
Previous studies have established links between vitamin K and long-term conditions that can
raise the risk of mobility disability. These conditions include cardiovascular disease and
osteoarthritis. However, none of those earlier investigations had examined the relationship
between vitamin K and mobility disability directly.
M. Kyla Shea is the new study's first and corresponding author. She researches Vitamin K at the
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston,
Shea explains that: Low vitamin K status has been associated with the onset of chronic diseases
that lead to disability, but the work to understand this connection is in its infancy."
She and her colleagues believe that they are the first to evaluate the relationship between
&vitamin K status and incident mobility disability" in older adults.
The new evidence builds on earlier studies that have associated low levels of circulating vitamin
K with slower gait speed and a higher risk of osteoarthritis," Shea explains.
Vitamin K is a group of fat-soluble compounds that have a similar chemical structure and are
present in some foods. Phylloquinone is the main dietary form of vitamin K and is present
mainly in leafy greens.
To assess vitamin K status, Shea and her colleagues measured two blood biomarkers:
phylloquinone and uncarboxylated matrix Gla protein (ucMGP), a protein that requires vitamin
K. They note that ucMGP in the blood increases when vitamin K status is low."
The Health ABC study assessed mobility every 6 months for a period of between 6 and 10 years.
The participants attended clinics and also completed interviews on the phone.
The researchers defined mobility limitation as two consecutive 6-monthly reports of
experiencing any amount of difficulty either with walking a quarter of a mile or climbing 10
steps without resting."
They defined mobility disability as two consecutive 6-monthly reports of experiencing a lot of
difficulty or inability" to complete the same walking and climbing challenge.
The researchers found that developing mobility limitation was almost 1.5 times more likely in
those with low blood levels of phylloquinone compared with those who had sufficient levels.
In addition, the chance of developing mobility disability for those low in phylloquinone was
almost double that of those with sufficient levels.
There was no clear relationship between either mobility limitation or disability with blood levels
The researchers call for further studies to confirm their findings and clarify the mechanisms that
might link vitamin K to mobility