Plain language summary
Being overweight increases the risk of the development of metabolic conditions such as non-alcoholic fatty liver disease (NAFLD). Omega-3 polyunsaturated fatty acid (PUFA) supplementation is recommended for prevention of chronic disease, and is thought to reduce liver fat, but there have been few randomised controlled trials that accurately measure liver fat. The aim of this double-blind randomised controlled trial was to assess the effect of 12 weeks of supplementation with omega-3 PUFA from fish oil on liver fat, liver tests, and body composition. Fifty healthy overweight men were given either fish oil (1,728 mg marine triglycerides, of which 588 mg EPA and 412 mg DHA, combined with 200 mg antioxidant, coenzyme Q10) or placebo (capsules containing 2g olive oil) daily for 12 weeks. Participants were assessed at the beginning of the study, and following 6 and 12 weeks of supplementation. At the start of the study, 16 (32%) participants met the criteria for NAFLD (>5.5% liver fat). There were no significant changes in liver fat, liver function or body composition in either of the groups over 12 weeks. When the researchers looked at the results for those participants with NAFLD at the start of the study, there were no significant changes here either. The authors concluded that omega-3 PUFA did not appear to be an effective agent for reducing liver fat in overweight men. The factors determining the health benefits of omega-3 PUFA supplementation on an individual level need to be clarified.
Abstract
Being overweight increases the risk of the development of metabolic conditions such as non-alcoholic fatty liver disease (NAFLD), which is itself an independent predictor of cardiovascular disease. Omega-3 polyunsaturated fatty acid (PUFA) supplementation is recommended for prevention of chronic disease, and is thought to reduce raised liver fat, yet there have been few randomized controlled trials with accurate measurement of liver fat. We assessed the effect of 12 weeks of supplementation with omega-3 PUFA from fish oil versus placebo on quantified liver fat, liver tests, and body composition including visceral adipose tissue (VAT) in a double-blind randomized controlled trial. Fifty apparently healthy overweight men (BMI 25.0⁻29.9 kg/m²; waist > 94 cm) were randomly allocated to consume fish oil (total daily dose: 1728 mg marine triglycerides, of which 588 mg EPA and 412 mg DHA, combined with 200 mg antioxidant, coenzyme Q10) or placebo (olive oil capsules) daily for 12 weeks. Liver fat was assessed using proton magnetic resonance spectroscopy. All outcomes were assessed at baseline and following 6 and 12 weeks of supplementation. Baseline liver fat was 4.6 ± 0.5% (range: 0.6 to 18.2%); 16 (32%) participants met the criteria for NAFLD (>5.5% liver fat). Repeated measures ANOVA revealed no significant time or group × time effect for fish oil versus placebo for liver fat, liver enzymes, anthropometry, or body composition including VAT (p > 0.05 for all), with similar finding for sub-analysis of participants with NAFLD. Omega-3 PUFA did not appear to be an effective agent for reducing liver fat in overweight men. The factors determining the health benefits of omega-3 PUFA supplementation on an individual level need to be clarified.
Methodological quality
Jadad score
:
5
Allocation concealment
:
Yes
