A Harvard University team found that neither vitamin D nor omega-3 fatty acids (FA) were associated with improvement in knee symptoms in older adults with chronic diurnal knee pain and self-reported knee OA when compared to placebo.
“Our study complements this evidence by using a large, racially diverse, population-based cohort with more than four years of follow-up,” says the team, led by Dr. Lindsey MacFarlane, lecturer in medicine at Brigham and Women’s Hospital in Boston, Massachusetts.
“Our results further support that vitamin D supplementation doses do not play a role in reducing knee pain in patients with OA, even in the low vitamin D subgroup.”
Recent interest has centered on the role of vitamin D in OA due to vitamin D’s role in bone resorption and muscle strength, as well as its anti-inflammatory properties.
Marine omega-3s found in fish oils have also been touted for their ability to reduce inflammation and the catabolic environment that promotes cartilage breakdown.
While studies have shown a link between lower vitamin D levels and pain and OA progression, several randomized controlled trials (RCTs) on vitamin D supplementation in OA have produced conflicting results.
However, fewer RCTs have been performed with fish oil a remarkable paperConducted a two-year RCT of low- or high-dose fish oil in patients with symptomatic knee OA.
Here the team showed that participants with low-dose fish oil had statistically significantly lower pain scores than the high-dose group after 18 and 24 months. However, no placebo group was analyzed.
In this latest analysis, the team took results from a patient subgroup enrolled in the nationwide study VITamin D and OmegA-3 TriaL (VITAL) with a five-year randomized intervention for the primary prevention of cancer and cardiovascular disease.
Almost 1,400 people were randomly assigned to receive vitamin D3 (cholecalciferol; 2000 IU / day), marine omega-3 fatty acids (Omacor 1 g / d, 840 mg eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in an amount of 1.3 up to supplement 1 ratio) or placebo and followed for 5.3 years.
The group completed a pain and stiffness test that looked at the effects of pain on performing activities such as walking and climbing stairs.
The results showed that at no point during the follow-up did the pain scores differ between vitamin D or omega-3 FA and placebo. No change in analgesic use was found between the two groups during the study period.
“During the mean follow-up period of 5.3 years, a slight decrease in reported knee pain was observed. However, this occurred in both the treatment and placebo groups and may be due to regression of the mean and some loss of total knee replacement (TKR) participants), ”says the team.
“At no point in time did the pain scores differ statistically between treatment and placebo, and the treatment arm had no significant influence on pain scores over time. .
“No clinically or statistically significant reductions in WOMAC function or stiffness were seen in either treatment group compared to placebo.”
Conflicting Evidence .
The team points to previous conflicting RCTs looking at the effectiveness of vitamin D for knee pain in OA. In a two-year study of subjects with symptomatic knee OA and low vitamin D (12.5 nmol / L to 60 nmol / L) randomized to vitamin D versus placebo, there were no significant changes in WOMAC pain scores between treatment groups .
However, the post-hoc analysis showed significant improvements in the vitamin D group for the overall WOMAC score and WOMAC function as well as a larger proportion of the OMERACT-OARSI responders.
In a year Pilot testIn subjects with symptomatic knee OA and vitamin D insufficiency, randomized to vitamin D compared to placebo, the study reported a significant improvement in pain and function scores in the vitamin D group
However, these differences did not meet the threshold for minimal clinically improved difference.
Source: Arthritis Rheumatol
Published online: doi.org/10.1002/art.41416.
“The Effects of Vitamin D and Marine Omega-3 Fatty Acids Supplementation on Chronic Knee Pain in Older Adults in the US: Results of a Randomized Study.”
Authors: Iversen MD, Katz JN, Costenbader KH.