Insufficient intake of vitamin D has been associated with numerous health conditions, including musculoskeletal disorders and chronic pain. Low levels of 25-hydroxyvitamin D have been linked with a greater incidence of chronic pain and associations between various types of pain, season, and latitude may also suggest a role of vitamin D in chronic pain. An updated review in the Cochrane Library examined data published since the original 2010 review on vitamin D for the treatment of chronic pain conditions.
The ten studies on 811 participants investigated vitamin D for rheumatoid arthritis, knee osteoarthritis, polymyalgia rheumatica, non-specific musculoskeletal pain, diffuse musculoskeletal pain, and fibromyalgia; mean age ranged from 42–68 years and vitamin D preparation, dose, and duration varied significantly. The primary outcome was patient-reported clinically significant pain relief with other patient-rated pain outcomes as well as adverse events as secondary endpoints. Most studies reported treatment group average outcomes only, with only two studies reporting responder pain outcomes. Three studies were at high risk of bias due to incomplete outcome data and the other studies were at unclear or low risk of bias.
No convincing beneficial effects of vitamin D supplementation for chronic pain were observed in the studies and there were no consistent patterns that vitamin D treatment was associated with improved efficacy vs. placebo for any chronic painful condition (low quality evidence). Some participants were vitamin D sufficient at baseline, so a vitamin D effect could be difficult to prove. Overall, there was no consistent pattern in the efficacy of vitamin D for chronic pain. Based on the presently available research, pain intensity reduction should not be expected with vitamin D supplementation without additional investigation.