An analysis suggests that supplementing with either vitamin D or omega-3 fatty acids has no effect in the long-term on osteoarthritic knee pain.
A team from Harvard University analysed the results from a subgroup of patients in the VITAL study which was designed to examine the effect of both vitamin D and omega-3 fatty acid supplementation on the primary prevention of cancer. Patients were randomised to receive vitamin D3 (2000IU/day) or omega-3 fatty acids 1g/day or placebo and followed by 5.3 years. Within this group was a “knee pain cohort” of self-reported chronic knee pain at enrolment and who, based on screening questions, appeared to have osteoarthritis.
Patients completed a pain and stiffness tool designed to assess the impact on pain from daily activities such as walking, climbing stairs etc and the analysis comprised 674 patients taking vitamin D and 695 omega-3 fatty acids, with a mean age of 67 years in both arms.
The results showed that at the last appointment, the mean pain scores were not significantly different between the vitamin D and omega-3 fatty acid groups compared to their respective placebo groups. There was also no change in analgesic use between the two groups over the study period.
The authors concluded that neither intervention was of value in osteoarthritis.
Iversen MD, Katz JN, Costenbader KH. The effects of Vitamin D and Marine Omega-3 fatty acid supplementation on chronic knee pain in older US adults: results from a randomised trial. Arthritis Rheumatol 2020; https://doi.org/10.1002/art.41416