Effect of egg consumption on health outcomes: An updated umbrella review of systematic reviews and meta-analysis of observational and intervention studies

Aims: To evaluate the effect of egg consumption on health outcomes. Data synthesis: A systematic search in PubMed, Scopus, Lilacs, and Web of Science was developed using terms ("egg consumption" or "egg intake") and ("health" or "chronic diseases" or "diabetes" or "cancer" or "cholesterol" or "dyslipidemia"), and meta-analyses of observational or interventional studies published since January 2020 were included. The studies' quality was evaluated through AMSTAR-2 and NutriGrade, and the strength of evidence according to sample size, heterogeneity, and quality of articles. Fourteen meta-analyses were included (10 observational, 4 interventional studies). The wide range of outcomes, with substantial variability and high heterogeneity, indicated a lack of robust evidence. The overall quality of studies was critically low. The level of evidence was very weak for all the significant associations: risk of heart failure (RR 1.15; 95%CI: 1.02-1.30), cancer mortality (RR 1.13; 95%CI 1.06-1.20), higher levels of LDL cholesterol (WMD 7.39; 95%CI 5.82-8.95), total cholesterol (WMD 9.12; 95%CI 7.35-10.89), and apolipoprotein B-100 (WMD 0.06; 95%CI 0.03-0.08). Conversely, egg intake has been weakly associated with improvements in HDL cholesterol (WMD 1.37; 95%CI 0.49-2.25), apolipoprotein A1 (WMD 0.03; 95%CI 0.01-0.05), and growth parameters in children (WMD 0.47; 95%CI 0.13-0.80). No evidence of association was found among all cardiovascular outcomes and all-cause mortality risk between high vs. low egg consumption. Conclusion: Due to the critically low strength of studies, insufficient evidence is available to discourage egg consumption, suggesting eggs can be part of a healthy diet.