We conducted a meta-analysis to evaluate the effects of probiotics and prebiotics on the immune response to influenza vaccination in adults. We conducted a literature search of Pubmed, Embase, the Cochrane Library, the Cumulative Index to Nursing and Allied Health (CINAHL), Airiti Library, and PerioPath Index to Taiwan Periodical Literature in Taiwan. Databases were searched from inception to July 2017. We used the Cochrane Review risk of bias assessment tool to assess randomized controlled trial (RCT) quality. A total of 20 RCTs comprising 1979 adults were included in our systematic review. Nine RCTs including 623 participants had sufficient data to be pooled in a meta-analysis. Participants who took probiotics or prebiotics showed significant improvements in the H1N1 strain seroprotection rate (with an odds ratio (OR) of 1.83 and a 95% confidence interval (CI) of 1.19–2.82, p = 0.006, I2 = 0%), the H3N2 strain seroprotection rate (OR = 2.85, 95% CI = 1.59–5.10, p < 0.001, I2 = 0%), and the B strain seroconversion rate (OR = 2.11, 95% CI = 1.38–3.21, p < 0.001, I2 = 0%). This meta-analysis suggested that probiotics and prebiotics are effective in elevating immunogenicity by influencing seroconversion and seroprotection rates in adults inoculated with influenza vaccines.

BackgroundInfluenza infection is a common disease with a huge disease burden. Influenza vaccination has been widely used, but concerns regarding vaccine efficacy exist, especially in the elderly. Probiotics are live microorganisms with immunomodulatory effects and may enhance the immune responses to influenza vaccination.MethodsWe conducted a systematic review and meta-analysis to determine the influence of prebiotics/probiotics/synbiotics supplementation on vaccine responses to influenza vaccination. Studies were systematically identified from electronic databases up to July 2017. Information regarding study population, influenza vaccination, components of supplements, and immune responses were extracted and analyzed. Twelve studies, investigating a total of 688 participants, were included in this review.ResultsPatients with prebiotics/probiotics supplements were found to have higher influenza hemagglutination inhibition antibody titers after vaccination (for A/H1N1, 42.89 vs 35.76, mean difference =7.14, 95% CI =2.73, 11.55, P=0.002; for A/H3N2, 105.4 vs 88.25, mean difference =17.19, 95% CI =3.39, 30.99, P=0.01; for B strain, 34.87 vs 30.73, mean difference =4.17, 95% CI =0.37, 7.96, P=0.03).ConclusionSupplementation with prebiotics or probiotics may enhance the influenza hemagglutination inhibition antibody titers in all A/H1N1, A/H3N2, and B strains (20%, 19.5%, and 13.6% increases, respectively). Concomitant prebiotics or probiotics supplementation with influenza vaccination may hold great promise for improving vaccine efficacy. However, high heterogeneity was observed and further studies are warranted.

Cardiovascular disease (CVD) risk in individuals with metabolically healthy obesity (MHO) is unclear. We searched databases from inception to May 2019. Data were pooled using a random effects model. Newcastle-Ottawa Scale assessment was performed. Primary and secondary outcomes were CVD risk and all-cause mortality. Forty-three studies involving 4,822,205 cases were included. The median percentage of females, age and duration of follow-up was 52%, 49.9 years and 10.6 years, respectively. The mean Newcastle-Ottawa Scale score of the articles was 7.9 ± 1.0. Compared to individuals with a metabolically healthy normal weight, individuals with MHO had higher adjusted risk of CVD and all-cause mortality. We identified a significant linear dose-response relationship between body mass index (BMI) and CVD risk among metabolically healthy individuals (p < 0.001); every unit increase in BMI increased the CVD risk. Multivariate meta-regression analysis showed that an increased proportion of women and age resulted in the risk of CVD affected by MHO reduction (p = 0.014, p = 0.030, respectively). Age and sex explained the observed heterogeneity and reported the adjusted R2. MHO resulted in a significantly increased risk for CVD; therefore, long-term weight loss should be encouraged.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have shown impressive effects in reducing major vascular events in several randomized controlled trials (RCTs). The purpose of this study was to perform a meta-analysis to evaluate the effect of SGLT2 inhibitors on the risk of stroke and its subtypes. All data from prospective RCTs up to 20 October 2020 involving SGLT2 inhibitors that reported stroke events as the primary endpoint or safety in subjects with type 2 diabetes were subjected to meta-analysis. Five eligible RCTs (EMPA-REG, CANVAS, DECLARE-TIMI 58, CREDENCE and VERTIS CV) involving 46,969 participants were included. Pooled analysis of the RCTs showed no significant effect of SGLT2 inhibitors on total stroke [risk ratio (RR) = 0.95; 95% confidence interval (CI) 0.79–1.13, P = 0.585]. Subgroup analysis indicated that SGLT2 inhibitors had no significant effect against fatal stroke, non-fatal stroke, ischemic stroke or transient ischemic attack. When only hemorrhagic stroke was included, SGLT2 inhibitors were associated with a significant 50% reduction compared with placebo (RR = 0.49, 95% CI 0.30–0.82, P = 0.007). This meta-analysis shows that SGLT2 inhibitors have a neutral effect on the risk of stroke and its subtypes but a potential protective effect against hemorrhagic stroke.

Summary The risk of cancer among adults with metabolically healthy obesity (MHO) has not yet been established. We systematically searched from inception to 15 March 2020. We included prospective cohort studies that compared participants with MHO and participants with metabolically healthy non‐obesity (MHNO) for incidence of any type of cancer. Benign tumors, cancer mortality or cancer prognosis were not in the scope of our analysis. The Newcastle–Ottawa Scale was used for quality assessment. Ultimately, eight studies with a total of 12 542 390 participants were included. The pooled meta‐analysis using random effect model showed participants with MHO demonstrated a significantly increased risk of developing cancer (odds ratio [OR], 1.14; 95% confidence interval [CI], 1.05 to 1.23; and I2 = 39%) than those with MHNO. The subgroup analysis revealed a higher pooled estimate (OR, 1.17; 95% CI, 1.01–1.35; and I2 = 56%) in comparison with metabolically healthy normal weight. No evidence of effect modification by age, sex, ethnicity, smoking, sample size or length of follow‐up was found. In conclusion, the present study reports a positive association between MHO and cancer incidence. All individuals with obesity, even in the absence of metabolic dysfunction, should be encouraged to lose weight.