Low Vitamin K Status Associated with Osteoarthritis
What problem was studied?
Poor intake of vitamin K, a fat-soluble vitamin present in leafy, green vegetables and some vegetable oils, is a common problem with potentially negative effects on a number of body systems and functions, including joint health. Insufficient vitamin K can result in abnormal cartilage and bone mineralization and thus possibly the formation of osteophytes (“bone spurs”) that are seen in osteoarthritis (OA). Arthritis Foundation postdoctoral fellow Tuhina Neogi, MD, and colleagues undertook a study to determine if poor vitamin K status is associated with the features of OA seen on X-ray.
What was done in the study?
The researchers conducted an analysis of 672 participants in the Framingham Offspring study, a study of the adult children (and their spouses) of the original Framingham Heart Study, which was designed to study the incidence and prevalence of cardiovascular disease and its risk factors over time. The study participants had already had blood tests to measure levels of phylloquinone (the primary form of vitamin K) between 1996 and 1998 as well as hand and knee X-rays between 2002 and 2004.
The investigators calculated the prevalence of OA, bone spurs and joint-space narrowing (an indication of cartilage destruction) in the participants’ joints in each of four ranges of blood phylloquinone levels. Results of those in the highest-level phylloquinone groups were compared with those in the lowest group. The researchers conducted the analyses in hands and knees separately, accounting for a number of factors – including age, sex, body mass index, total energy intake and bone mineral density.
What were the study results?
The prevalence of osteoarthritis, bone spurs, and joint-space narrowing decreased significantly with increasing blood levels of phylloquinone. In other words, people who had the highest vitamin K levels had the least severe OA as evidenced by the number of joints affected and the severity of affected joints.
These observational data support the hypothesis of an association between low plasma levels of vitamin K and increased prevalence of OA manifestations in the hand and knee.
What is the relevance to people with osteoarthritis?
Although research has yet to prove that consuming a diet rich in vitamin K will actually prevent osteoarthritis or repair damage that has occurred, it does suggest that vitamin K may help slow or stop the progression of OA. Foods that are good sources of vitamin K include spinach, leaf lettuce, broccoli, kale, asparagus and olive, soy bean and canola oils. The same research group has been awarded another Arthritis Foundation award to further study vitamin K and OA in a clinical trial.