Effects of Vitamin D and marine-derived Omega-3 Fatty Acid Supplementations on Inflammation and Clinical Outcomes in Autoimmune Diseases: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Keywords:
Vitamin D, Marine Omega-3 Fatty Acid, Rheumatoid Arthritis, Systemic Lupus Erythematosus, Psoriasis, Adjunct therapiesAbstract
Objective:
Vitamin D and omega-3 fatty acids are proposed immunomodulatory therapies due to their anti-inflammatory properties in autoimmune diseases. However, evidence remains inconsistent. This meta-analysis evaluates their impact on inflammation and disease activity in autoimmune diseases
Methods:
A systematic search (June 24–July 21, 2024) was conducted using PubMed, ScienceDirect, Google Scholar, and Cochrane Library. Eligible randomized controlled trials assessed vitamin D or marine-derived omega-3 fatty acids on inflammatory biomarkers (CRP as primary outcome) in autoimmune diseases, including Rheumatoid Arthritis, Systemic Lupus Erythematosus, and Psoriasis. Study quality was assessed using Cochrane Risk-of-Bias tool with heterogeneity evaluated via I² in a random-effects model using RevMan.
Results:
Nineteen RCTs (1,827 participants) included; 15 qualified for meta-analysis. Neither vitamin D nor omega-3 supplementation significantly reduced CRP levels. Vitamin D improved VAS-pain scores in RA (SMD: –0.22; 95% CI: –0.45 to –0.00; I² = 0%; p = 0.05). Omega-3 significantly reduced Tender Joint Count (SMD: –1.59; 95% CI: –2.73 to –0.46; I² = 70%; p = 0.006) and showed a statistically significant effect on IL-6 levels (SMD: 0.56; 95% CI: 0.02 to 1.10; I² = 65%; p = 0.04) in RA; however, this finding was inconsistent across individual studies and should be interpreted cautiously. No significant effects were observed for SLE or psoriasis. Funnel plots were not considered reliable for assessing publication bias due to the limited number of studies. Risk-of-bias assessment rated 2 studies as low risk, 7 moderate, and 10 high.
Conclusion:
Vitamin D and omega-3 fatty acid supplementation showed no significant effect on CRP levels and limited, inconsistent effects on clinical outcomes in autoimmune diseases. The overall evidence remains inconclusive due to small sample sizes, heterogeneity, and risk of bias. Larger, well-designed randomized controlled trials are required to confirm these findings.
Keywords:
Vitamin D; Marine Omega-3 Fatty Acid; Rheumatoid Arthritis; Systemic Lupus Erythematosus; Psoriasis.
