Role of vitamin D on knee osteoarthritis pain: a systematic review

Vitamin D3 (Cholecalciferol) has the chemical formula of (C27H44O), molecular weight (384.6), exact mass (384.339216023), and mono-isotopic mass (384.339216023). The researchers conducted this study to examine the role of Vitamin D on the knee osteoarthritis pain. The original published articles (interventional or correlational) aimed to investigate the role of vitamin D on Knee OA pain. The search was done by using the keywords “pain, knee osteoarthritis, osteoarthritis, Vitamin D, Vitamin D3, knee, Cholecalciferol, and vitamin D deficiency” and these mentioned keywords were used by OR and AND search methods. Regarding gray texts, all related articles and their references were reviewed. Based on the findings of 15 articles, there was no relationship between vitamin D and pain in 2 articles, pain was lower in the high vitamin D group (No significance 0.05) in 1 article, and increasing vitamin D reduced pain in 12 articles. In 9 articles, the search method was Randomized Trial, and in 6 ones, it was cross-sectional. According to the findings, although in most reviewed articles, vitamin D led to the reduction of Knee OA pain, in some of them, the difference in pain reduction between the group receiving vitamin D and the placebo group was not significant. Therefore, acceptable evidence for its effectiveness is not available and it is necessary to conduct more studies in this field.