Objective: The purpose of the systematic review and meta-analysis was to determine if low-ratio n-6/n-3 long-chain polyunsaturated fatty acid (PUFA) supplementation affects serum inflammation markers based on the current studies. Methods: PubMed, Embase and The Cochrane library databases were systematically searched to find randomized controlled trials (RCTs) on the effect of low-ratio n-6/n-3 PUFA intervention on inflammation markers up to July 2020. Data were pooled using standardized mean difference (SMD) and 95% confidence intervals (95% CI), with P value ≦ 0.05 as statistical significance. Results: Thirty-one RCTs were included in the meta-analysis. The analysis indicated that increasing low-ratio n-6/n-3 PUFA supplementation decreased the level of tumor necrosis factor-α (TNF-α) (SMD = −0.270; 95% CI: −0.433, −0.106; P = 0.001) and interleukin 6 (IL-6) (SMD = −0.153; 95% CI: −0.260, −0.045; P = 0.005). There were no significant effects on C-reactive protein (CRP) (SMD = −0.027; 95% CI: −0.189: 0.135; P = 0.741). Subgroup analysis indicated that there was a significant reduction in TNF-α serum concentration in subjects from Asia (SMD: −0.367; 95% CI: −0.579, −0.155; P = 0.001) and in subjects with diseases (SMD: −0.281; 95% CI: −0.436, −0.127; P < 0.001). In the subgroup of the n-6/n-3 ratio ≦5, low-ratio n-6/n-3 PUFA supplementation could decrease the level of TNF-α (SMD: −0.335; 95% CI: −0.552, −0.119; P = 0.002). Serum IL-6 decreased significantly in patients from the Europe subgroup (SMD: −0.451; 95% CI: −0.688, −0.214; P < 0.001), but not in Asia (SMD: −0.034; 95% CI: −0.226, 0.157; P = 0.724), North America (SMD: −0.115; 95% CI: −0.274, 0.044; P = 0.157) and Oceania (SMD: 0.142; 95% CI: −0.557, 0.842; P = 0.690). Conclusion: Low-ratio n-6/n-3 PUFA supplementation could decrease significantly the concentration of serum TNF-α and IL-6, but not decrease CRP concentration.

Animal experimental studies have found that resistant starch can significantly improve bowel function, but the outcomes are mixed while conducting human studies. Thus, we conducted a systematic review and meta-analysis of randomized controlled trials to evaluate the relationship between resistant starch supplementation and large intestinal function. Three electronic databases (PubMed, Embase, Scopus) were searched to identify eligible studies. The standardized mean difference (SMD) or weighted mean difference (WMD) was calculated using a fixed-effects model or a random-effects model. The pooled findings revealed that resistant starch significantly increased fecal wet weight (WMD 35.51 g/d, 95% CI 1.21, 69.82) and butyrate concentration (SMD 0.61, 95% CI 0.32, 0.89). Also, it significantly reduced fecal PH (WMD −0.19, 95% CI −0.35, −0.03), but the increment of defecation frequency were not statistically significant (WMD 0.04stools/g, 95% CI −0.08, 0.16). To conclude, our study found that resistant starch elicited a beneficial effect on the function of large bowel in healthy adults.