Association of plasma omega-6 and omega-3 polyunsaturated fatty acids with synovitis in the knee: The MOST study
- Source: Osteoarthritis and Cartilage, Feb 4, 2012
By Kristin R Baker, et al.
[Note: Synovium is a thin layer of cells lining the joints and joint-stabilizing tendons, which when healthy produces joint lubricating synovial fluid. The ideal omega-3 to omega-6 ratio is thought to be 1:2 to 1:4, but with the typical Western diet it’s more like 1:20.]
In osteoarthritis (OA) the synovium is often inflamed and inflammatory cytokines contribute to cartilage damage.
Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) have anti-inflammatory effects whereas omega-6 polyunsaturated fatty acids (omega-6 PUFAs) have, on balance, proinflammatory effects. The goal of our study was to assess the association of fasting plasma phospholipid omega-6 and omega-3 PUFAs with synovitis as measured by synovial thickening on contrast enhanced (CE) knee MRI and cartilage damage among subjects in the Multicenter Osteoarthritis Study (MOST).
MOST is a cohort study of individuals who have or are at high risk of knee OA. [The collaborative is tracking patients long-term “to identify factors that affect the occurrence and progression of osteo-arthritis related knee symptoms.”]
An unselected subset of participants who volunteered obtained CE 1.5 T MRI of one knee. Synovitis was scored in six compartments and a summary score was created. This subset also had fasting plasma, analyzed by gas chromatography for phospholipid fatty acid content, and non-CE MRI, read for cartilage morphology according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS) method.
The association between synovitis and cartilage morphology [structure] and plasma PUFAs was assessed using logistic regression after controlling for the effects of age, sex, and BMI.
472 out of 535 subjects with CE MRI had complete data on synovitis, cartilage morphology and plasma phospholipids. Mean age was 60 years, mean BMI 30, and 50% were women.
We found an inverse relation between total omega-3 PUFAs and the specific omega-3, docosahexaenoic acid [DHA] with patellofemoral cartilage loss, but not tibiofemoral cartilage loss or synovitis. [That is, the lower the omega-3s, the greater was the cartilage loss in the joint between the thigh bone and knee cap, and conversely the higher the omega-3 level, the less cartilage loss.]
A positive association was observed between the omega-6 PUFA, arachidonic acid, and synovitis. [Higher omega-6, more synovial inflammation.]
In conclusion, systemic levels of omega-3 and omega-6 PUFAs which are influenced by diet, may be related to selected structural findings in knees with or at risk of OA.
Future studies manipulating the systemic levels of these fatty acids may be warranted to determine the effects on structural damage in knee OA.
Source: Osteoarthritis and Cartilage, Feb 4, 2012. By Baker KR, Matthan NR, Lichtenstein AH, Niu J, Guermazi A, Roemer F, Grainger A, Nevitt MC, Clancy M, Lewis CE, Torner JC, Felson DT. Boston University Clinical Epidemiology Research and Training Unit, Tufts Jean Mayer Human Nutrition Research Center and Department of Radiology, and Boston University Medical Center, Boston, Massachusetts, USA; ULeeds, Leeds, United Kingdom; Department of Epidemiology and Biostatistics, University of California, San Francisco, USA; Department of Preventive Medicine, University of Alabama, Birmingham, USA; Department of Epidemiology, University of Iowa, Iowa City, USA. [Email: firstname.lastname@example.org]