Vitamin D and Fish Oil Fail Osteoarthritis Trial

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New research published in Arthritis and Rheumatology shows that vitamin D and marine omega‐3 fatty acids (n‐3 FA) do not offer long-term relief from knee pain, stiffness or function in older adults with chronic knee pain.

The two supplements have been promoted commercially as possible treatments for knee pain. In theory, it seemed plausible because vitamin D promotes bone resorption and bone strength and has anti-inflammatory properties. Omega-3 fatty acids have anti-inflammatory effects and they promote cartilage degradation. But, apparently, neither treatment is associated with statistically significant improvements in pain, improved function or mobility.

This was a randomized, double-blind, placebo-controlled clinical trial of 25,871 adults enrolled in VITamin D and OmegA-3 TriaL (VITAL). The knee pain analysis was based on a subset of 1,398 patients (66% female, mean age 67.7 years) with knee pain of which 674 were randomized to active vitamin D and 695 received omega‐3 fatty acids. They were followed for 5.3 years and their pain scores were measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

No statistical difference in pain, function or stiffness was found between the vitamin D and placebo groups or the omega-3 fatty acid and placebo groups. Nor were there differences in the reduction of total knee replacement surgeries or a difference in the use of analgesics over the course of the five-year study.

“These results are in agreement with past smaller randomized control trials and suggest that supplementation of vitamin D or n-3 FA does not have a role in the management of symptomatic knee pain due to osteoarthritis,” wrote researchers who were led by Lindsey A. Macfarlane, M.D., MPH, of Brigham and Women’s Hospital in Boston.

“Identifying safe and inexpensive therapies that reduce pain could vastly improve management of chronic knee pain,” they wrote.

REFERENCE

Lindsey A. MacFarlane, Nancy R. Cook, Eunjung Kim, et al. "The Effects of Vitamin D and Marine Omega‐3 Fatty Acid Supplementation on Chronic Knee Pain in Older U.S. Adults: Results from a Randomized Trial," Arthritis and Rheumatology. First published: 25 June 2020, https://doi.org/10.1002/art.41416