Vitamin K is a nutrient that the body requires in small, regular amounts. It is essential for the formation of several substances called coagulation factors as well as protein C and protein S that work together to clot the blood when injuries to blood vessels occur and to prevent excessive clotting.
Insufficient Vitamin K can lead to excessive bleeding and easy bruising.
Vitamin K has been implicated in chronic diseases associated with increased risk for mobility disability, such as osteoarthritis and cardiovascular disease. However, the association between vitamin K status and mobility disability is unknown.
In a new study, scientists examined the association between vitamin K status and incident mobility disability in the Health, Aging, and Body Composition Study. They found a positive correlation between low levels of circulating vitamin K and mobility limitation and disability in older adults.
Kyla Shea, first and corresponding author and a nutrition scientist in the Vitamin K Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University said, “Because of our growing population of older people, it’s important for us to understand the variety of risk factors for mobility disability.”
“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. Here, we’re building on previous studies that found that low levels of circulating vitamin K are associated with slower gait speed and a higher risk of osteoarthritis.”
The new study examined two biomarkers: circulating levels of vitamin K (phylloquinone) and a functional measure of vitamin K (plasma ucMGP). Using participant data from the Health, Aging, and Body Composition Study (Health ABC), scientists discovered that older adults with vitamin K deficiency more likely to develop mobility limitation and disability. On the other hand, the biomarker plasma ucMGP did not display any visible relation with mobility limitation and disability.
Specifically, older adults with low circulating vitamin K levels were nearly 1.5 times more likely to develop mobility limitation and nearly twice as likely to develop mobility disability compared to those with sufficient levels. This was true for both men and women.
The study used data from 635 men and 688 women ages 70-79 years old, approximately 40 percent of whom were black, who participated in Health ABC. In Health ABC, mobility was assessed every six months for six to ten years through annual clinic visits and phone interviews in the intervening time.
Senior author Sarah Booth, a vitamin K and nutrition researcher, and director of the HNRCA said, “The connection we saw with low levels of circulating vitamin K further supports vitamin K’s association with mobility disability. Although the two biomarkers we looked at are known to reflect vitamin K status, biomarker levels can also be affected by additional known or unknown factors. Further experiments to understand the mechanisms of biomarkers and vitamin K and their role in mobility are needed.”
Circulating vitamin K levels reflect the amount of vitamin K in the diet. The best food sources of vitamin K include leafy greens such as spinach, kale and broccoli and some dairy products. For an average adult, one cup of raw spinach provides 145 micrograms (mcg) of vitamin K1 or 181 percent of the Daily Value; one cup of raw kale provides 113 mcg or 141 percent, and half of a cup of chopped boiled broccoli provides 110 mcg, or 138 percent.