Effect of n-3 (Omega-3) Polyunsaturated Fatty Acid Supplementation on Metabolic and Inflammatory Biomarkers and Body Weight in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of RCTs

Abstract

Beneficial effects of n-3 fatty acids on metabolic biomarkers in patients with type 2 diabetes (T2DM) has been reported. The objectives of this current research were to investigate the effects of n-3 supplementation on metabolic factors, weight, and body mass index (BMI) in patients with type 2 diabetes mellitus (T2DM), using a meta-analysis of randomized, controlled trials (RCTs). Online databases PubMed, Embase, Web of Science, and Science Direct were searched until 2021 to identify eligible articles. Thirty trials were included. The results showed that n-3 consumption can significantly reduce glycemic factors including fasting blood sugar (FBS) (−0.36 (−0.71 to −0.01)), glycated hemoglobulin (HbA1c) (−0.74 (−1.13 to −0.35)), and homeostatic model assessment of insulin resistance (HOMA.IR) (−0.58 (−1.13 to −0.03)). Furthermore, significant improvement in lipid profile including triglycerides (TG) (−0.27 (−0.37 to −0.18)), total cholesterol (−0.60 (−0.88 to −0.32)), low density lipoprotein (LDL) (−0.54 (−0.85 to −0.23)), and high-density lipoprotein (HDL) (0.60 (0.23 to 0.96)) levels were found in the present meta-analysis. The reduction in the inflammatory marker’s tumor necrosis factor-alpha (TNF-α) (−0.13 (−0.75 to 0.48)) and c-reactive protein (CRP) (−0.72 (−1.70 to 0.27)), as well as weight (−0.09 (−0.24 to 0.07)) and BMI (−0.13 (−0.29 to 0.02)) were not statistically significant. Furthermore, the findings revealed that the optimal dose and duration of n-3 consumption for patients with T2DM is 1000–2000 mg/d for more than 8 weeks. The present meta-analysis and review reveals that n-3 supplementation can improve glycemic factors and lipid profile in patients with T2DM. Furthermore, n-3 supplementation may provide beneficial effects on inflammatory markers and body weight if used at the appropriate dose and duration.

Effects of marine-derived and plant-derived omega-3 polyunsaturated fatty acids on erythrocyte fatty acid composition in type 2 diabetic patients

“…Fish oil and ALA have also been shown to exhibit anti-inflammatory effects [23][24][25]. Although the meta-analysis indicated that the reduction in the c-reactive protein were not statistically significant [20,26]. The reduction of IL-6 after EPA and DHA supplementation was significant in T2DM patients [27].…”

“…Many meta-analyses showed that EPA and DHA consumption can significantly reduce the levels of TG, LDL in T2DM patients [5,19]. And n-3 PUFA intake for both ≤8 and > 8 weeks could significantly increase the HDL level [20]. It is well established that T2DM is associated with dyslipidemia and that EPA and DHA supplementation has long been indicated in the treatment of hyperlipidemia in T2DM and pre-diabetes patients.…”

“…The possible reason for these inconsistent results is that the n-3 PUFA sources were different in the inclusion trials. Khalili's meta-analysis included the trials using ALA as the intervention [20]. Another reason is the intervention time.…”

“…Another study showed that flaxseed intake could reduce blood glucose and insulin levels and increase insulin sensitivity in overweight and obese people with pre-diabetes [31]. Besides, Khalili et al's metaanalysis found that there was the significant decrease of glucose after n-3 PUFA intake and the suggested dose and duration for T2DM patients was 1-2 g/d for more than 8 weeks [20]. This meta-analysis included studies administrating not only marine-based n-3 PUFA but also plant-based n-3 PUFA.…”

Polyunsaturated fatty acids and metabolic health: novel insights

“…The findings revealed that ω-3 PUFA doses >1 g/d significantly changed LDL and HDL levels. However, the statistically significant reduction in LDL concentration occurred only when ω-3 PUFAs were consumed for more than 8 weeks, while improvement in HDL level was noticed during all analyzed periods [41 ▪ ]. A previous meta-analysis of 45 RCTs, involving 2647 patients with T2DM, showed an association between ω-3 PUFA supplementation and favorable improvement in lipid profile, inflammatory markers and HbA1c level [42].…”