Effect of a Diet Supplemented with Marine Omega-3 Fatty Acids on Inflammatory Markers in Subjects with Obesity: A Randomized Active Placebo-Controlled Trial

Background/Objectives: Obesity is associated with chronic low-grade inflammation. Polyunsaturated fatty acids (PUFAs) such as omega-3 (n-3), are essential in anti-inflammatory processes. Therefore, the aim of this study was to evaluate the effect of a dietary intervention along with supplementation of 1.8 g of marine n-3 PUFAs on anthropometric, biochemical, and inflammatory markers in adults. Methods: An 8-week double-blind randomized clinical trial was conducted with a diet (200 kcal/day reduction each 4 weeks based on the estimated basal caloric expenditure) containing a n-6/n-3 PUFA ratio ≤ 5:1, along with daily 1.8 g of marine n-3 supplementation (EPA and DHA) vs. active placebo 1.6 g (ALA). A total of 40 subjects were included in the study, 21 in the marine omega-3 group and 19 in the active placebo group. Inclusion criteria included subjects aged 25 to 50 years with obesity as determined by body mass index (BMI) and/or abdominal obesity according to ATP III criteria. Results: The marine omega-3 supplemented group had a better effect compared to the active placebo group, increasing Resolvin D1 [129.3 (−90.1–193.5) vs. −16.8 (−237.8–92.5) pg/mL, p = 0.041], IL-10 [1.4 (−0.7–4.6) vs. −2.0 (−5–0.05) pg/mL, p = 0.001], and decreasing IL-6 [−0.67 (2.72–−0.59) vs. 0.03 (−0.59–1.84) pg/mL, p = 0.015], and MCP-1 [−29.6 (−94.9–5.50) vs. 18.3 (−97.3–66.35) pg/mL, p = 0.040]. Conclusions: A diet supplemented with marine n-3 improves inflammatory markers by increasing systemic levels of Resolvin D1 and IL-10 and decreasing IL-6 and MCP-1.