The effect of oral omega-3 polyunsaturated fatty acid supplementation on muscle maintenance and quality of life in patients with cancer: A systematic review and meta-analysis

Rationale: Omega-3 polyunsaturated fatty acid (PUFA) supplementation is a promising therapy for cancer-relatedmalnutrition, which affects 20-70% of patients with cancer1,2. This systematic review aimed to examine the effects of oralomega-3 PUFA supplementation on muscle maintenance and quality of life in patients with cancer.
Methods: Randomised controlled trials in cancer patients aged >18 years were retrieved from 5 electronic databases;MEDLINE (via PubMed), EMBASE, CENTRAL, CINAHL (via EBSCOhost), and Web of Science, from database inceptionuntil 31st of December 2019. Trials supplementing ≥600 mg/d omega-3 PUFA (oral capsules, pure fish oil or oralnutritional supplements) or a control intervention for ≥3 weeks were included. Meta-analyses were performed in RevManto determine the mean differences (MD) in muscle mass and quality of life between omega-3 PUFA and control groupswith 95% confidence intervals (CI) and I2 for heterogeneity.
Results: We included 33 studies in patients with various types of cancers and degrees of malnutrition. The Cochrane riskof bias tool graded most trials as ‘unclear’ or ‘high’ risk of bias. Meta-analyses showed oral omega-3 PUFA supplementsimproved physical functioning (MD: 6.33; 95% CI: 0.32, 12.34, p=0.04; I2=0%) and potentially reduced fatigue (MD: -6.21;95% CI: -13.473, 1.05, p=0.09; I2=14%). However, there was no significant effect of omega-3 PUFA supplements onmuscle mass, global health status, emotional functioning and symptoms (nausea and vomiting, loss of appetite anddiarrhoea).
Conclusion: This review provides evidence for the benefits of oral omega-3 PUFA supplementation on quality of life butnot on muscle maintenance in patients with cancer. Well-designed large-scale randomised controlled trials inhomogenous patient cohorts are required to confirm these findings.