Insufficient vitamin D levels associated with knee arthritis pain
Friday, November 9, 2012. Findings from the University of Florida reported on November 7, 2012 in the journal Arthritis & Rheumatism suggest a protective effect for increased vitamin D levels against knee osteoarthritis pain, which is greater in African Americans compared to those of European ancestry. African Americans have, on average, lower vitamin D levels compared to Caucasians, which may help explain some of the health disparities observed between these populations.
"Chronic pain is a disease," lead author Toni L. Glover, MSN, ARNP and her associates write. "The triage theory, proposed by Ames, hypothesizes long-term micronutrient deficiencies trigger chronic inflammation. In turn, chronic inflammation leads to chronic health conditions, many of which are characterized by pain as a disabling symptom. Recent research by Lee et al. supports the hypothesis that the etiology of osteoarthritis includes a systemic inflammatory component."
Forty-five African American and 49 Caucasians between 45 and 71 years of age with osteoarthritis of the knee completed questionnaires concerning knee symptoms and underwent tests of heat and mechanical pain sensitivity. Blood samples collected at the time of testing were analyzed for serum 25-hydroxyvitamin D.
African American participants reported more pain in comparison with Caucasian subjects. While half of the Caucasian participants had vitamin D levels that were lower than 30 nanograms per milliliter (ng/mL), these insufficient levels occurred in 84 percent of the African Americans. Average Caucasian vitamin D levels were 28.2 ng/mL, in contrast with 19.9 ng/mL among African Americans. "People associate vitamin D with good bone health," stated Glover, who is a research nurse practitioner and doctoral candidate at the University of Florida. "Yet, not everyone is aware of what factors decrease vitamin D and how low levels could contribute to health issues, including chronic pain."
"Our data demonstrate that differences in experimental pain sensitivity between the two races are mediated at least in part by variations in vitamin D levels," she concluded. "However, further studies are needed to fully understand the link between low vitamin D levels and racial disparities in pain. Although rare, vitamin D toxicity is possible and older adults should consult with their primary care provider regarding supplementation. It may be warranted that older black Americans with chronic widespread pain be screened for vitamin D deficiency to reduce disparities in pain."
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