Iron metabolism and anemia may play an important role in multiple organ dysfunction syndrome in Coronavirus disease 2019 (COVID-19). We conducted a systematic review and meta-analysis to evaluate biomarkers of anemia and iron metabolism (hemoglobin, ferritin, transferrin, soluble transferrin receptor, hepcidin, haptoglobin, unsaturated iron-binding capacity, erythropoietin, free erythrocyte protoporphyrine, and erythrocyte indices) in patients diagnosed with COVID-19, and explored their prognostic value. Six bibliographic databases were searched up to August 3rd 2020. We included 189 unique studies, with data from 57,563 COVID-19 patients. Pooled mean hemoglobin and ferritin levels in COVID-19 patients across all ages were 129.7 g/L (95% Confidence Interval (CI), 128.51; 130.88) and 777.33 ng/mL (95% CI, 701.33; 852.77), respectively. Hemoglobin levels were lower with older age, higher percentage of subjects with diabetes, hypertension and overall comorbidities, and admitted to intensive care. Ferritin level increased with older age, increasing proportion of hypertensive study participants, and increasing proportion of mortality. Compared to moderate cases, severe COVID-19 cases had lower hemoglobin [weighted mean difference (WMD), − 4.08 g/L (95% CI − 5.12; − 3.05)] and red blood cell count [WMD, − 0.16 × 1012 /L (95% CI − 0.31; − 0.014)], and higher ferritin [WMD, − 473.25 ng/mL (95% CI 382.52; 563.98)] and red cell distribution width [WMD, 1.82% (95% CI 0.10; 3.55)]. A significant difference in mean ferritin levels of 606.37 ng/mL (95% CI 461.86; 750.88) was found between survivors and non-survivors, but not in hemoglobin levels. Future studies should explore the impact of iron metabolism and anemia in the pathophysiology, prognosis, and treatment of COVID-19.

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Ultra-processed food (UPF) consumption have increased in the world during the last decades since they are hyper-palatable, cheap and ready-to-consume products. However, uncertainty exists on their impact on health. We conducted a systematic review and meta-analysis evaluating the association of UPF consumption with the all-cause mortality risk. Five bibliographic databases were searched for relevant studies. Random effects models were used to calculate pooled relative risks (RR) and 95% confidence intervals (CI). Of 6,951 unique citations, 40 unique prospective cohort studies comprising 5,750,133 individuals were included. Publication date of the included studies ranged from 1984 to2021. Compared to low consumption, highest consumption of UPF (RR=1.29, 95% CI 1.17-1.42), sugar-sweetened beverages (SSB) (RR=1.11, 95% CI, 1.04-1.18), artificially sweetened beverages (ASB) (RR=1.14, 95% CI, 1.05-1.22) and processed meat/red meat (RR=1.15, 95% CI, 1.10-1.21) were significantly associated with increased risk of mortality. On the contrary, breakfast cereals were associated with a lower mortality risk (RR=0.85, 95% CI, 0.79-0.92). Conclusion: This meta-analysis suggests that high consumption of UPF, SSB, ASB, processed meat and processed red meat might increase all-cause mortality, while breakfast cereals might decrease it. Future studies are needed to address lack of standardized methods in UPF categorization.