Liao reports receiving support from the Australian National Health and Medical Research Council grant.
In a study spanning 24 months, higher levels of vitamin K intake appeared to correspond with decreased knee symptoms in patients with osteoarthritis, according to data published in Arthritis Care & Research.
“To date there is no study examining if vitamin K intake is associated with reduced knee OA symptoms,” Zetao Liao, MD, of the rheumatology and immunology division of the third affiliated hospital of Sun Yat-Sen University, in Guangzhou, China, and co-authors wrote. “Therefore, the evidence for the relationship between vitamin K and knee OA is still insufficient.”
To investigate the associations between vitamin K intake and symptom and MRI structural changes in patients with knee OA, Liao and colleagues analyzed participants aged 50 to 79 years from the VIDEO study for 2 years. To be eligible for inclusion, participants were required to have symptomatic OA for at least 6 months, have knee pain between 20 mm and 80 mm on a 100 mm visual analogue scale, and demonstrate serum 25-hydroxyvitamin D levels ranging from 12.5 nmol per liter to 60 nmol per liter.
Participants completed questionnaires detailing knee symptoms at baseline and at every visit for 24 months. Symptoms were measured by way of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC). Visual analogue scores of knee pain were also assessed at each visit. Patients were also required to answer a survey measuring their dietary and physical activity habits at baseline. Cartlidge defects, bone marrow lesions and effusion-synovitis volumes were measured through MRI scans.
In all, 212 patients were followed and analyzed for 2 years. According to the researchers, higher vitamin K intake was “significantly associated” with a greater decrease in total WOMAC and dysfunction scores over that time. In addition, patients with severe visual analogue score-measured pain at baseline who consumed higher levels of vitamin K recorded better improvement in WOMAC scores, the authors wrote. There was no significant association between vitamin k intake and MRI feature changes.
In various subgroup analyses, vitamin K intake appeared to be negatively associated with changes in tibiofemoral, patellar and total cartilage defects in patients with severe baseline radiographic grade.
“The association of higher baseline vitamin K intake with decreased knee symptoms over 24 months in patients with knee OA in our study suggests that clinical trials examining the effect of vitamin K supplementation for knee OA symptoms are warranted,” Liao and colleagues wrote. “Whether there is an effect on knee structure is unclear and requires further investigation.”