We performed a systematic review and dose–response meta-analysis of observational studies assessing the association between UPF consumption and adult mortality risk. A systematic search was conducted using ISI Web of Science, PubMed/MEDLINE, and Scopus electronic databases from inception to August 2021. Data were extracted from seven cohort studies (totaling 207,291 adults from four countries). Using a random-effects model, hazard ratios (HR) of pooled outcomes were estimated. Our results showed that UPF consumption was related to an enhanced risk of all-cause mortality (HR = 1.21; 95% CI: 1.13, 1.30; I² = 21.9%; p < 0.001), cardiovascular diseases (CVDs)-cause mortality (HR = 1.50; 95% CI: 1.37, 1.63; I² = 0.0%; p < 0.001), and heart-cause mortality (HR = 1.66; 95% CI: 1.50, 1.85; I² = 0.0%; p = 0.022), but not cancer-cause mortality. Furthermore, our findings revealed that each 10% increase in UPF consumption in daily calorie intake was associated with a 15% higher risk of all-cause mortality (OR = 1.15; 95% CI: 1.09, 1.21; I² = 0.0%; p < 0.001). The dose–response analysis revealed a positive linear association between UPF consumption and all-cause mortality (P_nonlinearity = 0.879, P_{dose–response} = p < 0.001), CVDs-cause mortality (P_nonlinearity = 0.868, P_{dose–response} = p < 0.001), and heart-cause mortality (P_nonlinearity = 0.774, P_{dose–response} = p < 0.001). It seems that higher consumption of UPF is significantly associated with an enhanced risk of adult mortality. Despite this, further experimental studies are necessary to draw a more definite conclusion.

(1) Background: Recent individual studies have demonstrated that consumption of ultra-processed food (UPF) may be related to type two diabetes mellitus (T2DM). We aimed to synthesize the results from these individual studies by conducting an updated systematic review and meta-analysis of observational studies evaluating the association between UPF consumption and the risk of T2DM. (2) Methods: A systematic search was conducted using ISI Web of Science, PubMed/MEDLINE and Scopus electronic databases from inception up to August 2021. Data were extracted from five studies (one cross-sectional study and four cohort studies, totaling 230,526 adults from four different countries). Risk ratios (RR) of pooled results were estimated using a random-effects model. (3) Results: Our results revealed that higher UPF consumption was significantly associated with an increased risk of T2DM (RR = 1.74; 95% CI: 1.36, 2.22; I² = 68.9%; p < 0.001; n = 5). Linear dose-response analysis indicated that each 10% increase in UPF consumption (kcal/d) was associated with a 15% higher risk of T2DM (RR = 1.15; 95% CI: 1.06, 1.26; I² = 86.0%; p < 0.001; n = 5) among adults. Non-linear dose-response analysis demonstrated a positive linear association between UPF consumption and T2DM (p_nonlinearity = 0.13, p_{dose-response} < 0.001; n = 5) among adults. (4) Conclusions: A higher intake of UPF was significantly associated with an increased risk of T2DM. However, underlying mechanisms remain unknown and future experimental studies are warranted.

There is some evidence supporting the beneficial effects of a Paleolithic diet (PD) on cardiovascular disease (CVD) risk factors. This diet advises consuming lean meat, fish, vegetables, fruits, and nuts and avoiding intake of grains, dairy products, processed foods, and added sugar and salt. This study was performed to assess the effects of a PD on CVD risk factors including anthropometric indexes, lipid profile, blood pressure, and inflammatory markers using data from randomized controlled trials. A comprehensive search was performed in the PubMed, Scopus, ISI Web of Science, and Google Scholar databases up to August 2018. A meta-analysis was performed using a random-effects model to estimate the pooled effect size. Meta-analysis of 8 eligible studies revealed that a PD significantly reduced body weight [weighted mean difference (WMD) = −1.68 kg; 95% CI: −2.86, −0.49 kg], waist circumference (WMD = −2.72 cm; 95% CI: −4.04, −1.40 cm), BMI (in kg/m²) (WMD = −1.54; 95% CI: −2.22, −0.87), body fat percentage (WMD = −1.31%; 95% CI: −2.06%, −0.57%), systolic (WMD = −4.75 mm Hg; 95% CI: −7.54, −1.96 mm Hg) and diastolic (WMD = −3.23 mm Hg; 95% CI: −4.77, −1.69 mm Hg) blood pressure, and circulating concentrations of total cholesterol (WMD = −0.23 mmol/L; 95% CI: −0.42, −0.04 mmol/L), triglycerides (WMD = −0.30 mmol/L; 95% CI: −0.55, −0.06 mmol/L), LDL cholesterol (WMD = −0.13 mmol/L; 95% CI: −0.26, −0.01 mmol/L), and C-reactive protein (CRP) (WMD = −0.48 mg/L; 95% CI: −0.79, −0.16 mg/L) and also significantly increased HDL cholesterol (WMD = 0.06 mmol/L; 95% CI: 0.01, 0.11 mmol/L). However, sensitivity analysis revealed that the overall effects of a PD on lipid profile, systolic blood pressure, and circulating CRP concentrations were sensitive to removing some studies and to the correlation coefficients, hence the results must be interpreted with caution. Although the present meta-analysis revealed that a PD has favorable effects on CVD risk factors, the evidence is not conclusive and more well-designed trials are still needed.

Objective: We systematically reviewed available randomized clinical trials (RCTs) to elucidate the overall effects of synbiotic supplementation in patients with nonalcoholic fatty liver disease (NAFLD). Methods: PubMed, Scopus, ISI Web of science and Google Scholar were searched up to December, 2017. All RCTs using synbiotic supplements to treat NAFLD included in this systematic review and meta-analysis. Mean Difference (MD) was pooled using a random-effects model. Results: Eleven eligible databases from seven RCTs were identified for the present meta-analysis. Our results showed that synbiotic supplementation can decrease body weight, fasting blood sugar, insulin, low density lipoprotein cholesterol, total cholesterol, triglyceride, high-sensitivity C-reactive protein, tumor necrosis factor alpha, alanine transaminase and aspartate transaminase levels among patients with NAFLD. In contrast, synbiotic did not have favorable effects on body mass index (BMI), waist circumference, homeostasis model assessment for insulin resistance (HOMA-IR), and high density lipoprotein cholesterol (HDL) levels compared with the placebo group. Conclusion: The current study revealed that synbiotic supplementation has favorable effect on inflammatory factors, liver enzymes and some anthropometric indices, lipid profiles and glucose homeostasis parameters in patients with NAFLD.

Several investigations have been reported the beneficial effects of synbiotic in participants with obesity, but these findings have been inconsistent. Therefore, we systematically reviewed available randomized clinical trials (RCTs) to elucidate the overall effects of synbiotic supplementation on anthropometric indices among participants with overweight or obesity. Five electronic databases including PubMed, Scopus, ISI Web of science, Cochrane Library and Google Scholar were searched up to October 2018. All RCTs using synbiotic supplements to treat obesity included in this systematic review and meta-analysis. Weighted mean difference (WMD) was pooled using a random-effects model. The present meta-analysis of 23 randomized trials indicated that supplementation with synbiotic can decrease body weight (WMD: −0.80 kg; 95% CI: −1.56 to −0.03, p = 0.04) and WC (WMD: −2.07 cm; 95% CI: −3.11 to −1.03, p < 0.001). In contrast, synbiotic did not have favorite effects on BMI (WMD: −0.12 kg/m²; 95% CI: −0.40 to 0.16, p = 0.39) and body fat (WMD: 0.02%; 95% CI: −1.27 to 1.87, p = 0.74) compared with the placebo group. Meta-regression analyses revealed that the dosage of probiotic did not have any effect on anthropometric measures. Based on our findings, modulation of gut microbiota composition through synbiotic supplementation might have modest effects on body weight and waist circumference. In this field, however, our knowledge is progressing.

We aimed to conduct this dose-dependent meta-analysis to examine the relation between total protein, animal protein, and its sources with inflammatory bowel disease (IBD). We searched databases, comprising PubMed/Medline, Web of Science (ISI), Embase, and Google Scholar, for the published studies up to 28 March 2023. Prospective cohort study designs that investigated associations between dietary intake of various animal protein sources and with risk of IBD in the general population were identified. Eleven prospective cohort studies with 4,302,554 participants and 8067 cases were considered eligible. Findings indicated that higher intake of dairy was significantly associated with a lower risk of IBD (relative risk [RR]: 0.81; 95% confidence interval [CI]: 0.72, 0.90), Crohn disease (RR: 0.69; 95% CI: 0.56, 0.86), and ulcerative colitis (RR: 0.84; 95% CI: 0.75, 0.94). There was no association between different sources of animal protein and the risk of IBD. The dose-response analysis suggested that each 100 g/d increment in dietary total meat consumption was associated with a 38% greater risk of IBD. Moreover, a positive linear association was found between total meat intake and risk of IBD (P_nonlinearity = 0.522, P_{dose-response} = 0.005). Overall, among the dietary sources of protein, the risk of IBD increased only with increasing total meat intake, and the consumption of protein from dairy products was found to be a protective factor against the IBD risk. This trial was registered at PROSPERO as CRD42023397719.