Soy product consumption and the risk of all-cause, cardiovascular and cancer mortality: a systematic review and meta-analysis of cohort studies
Currently, the association of soy intake with total- and cause-specific mortality is inconsistent. The aim of this study was to systematically review cohort studies on the association between the consumption of soy products and mortality from all-causes, cardiovascular disease (CVD), and cancer. We conducted a systematic search of the PubMed/Medline, ISI Web of Knowledge and Embase electronic databases up to October 2016. Prospective cohort studies that examined the association of soy products with the risk of all-cause, CVD and cancer mortality using the relative risk (RR) or Hazard Ratio (HR) with 95% CIs were considered. Random-effect models were used to pool the study results and heterogeneity was examined using the I2 index and Q test. Finally, 7 studies were included for the meta-analysis; three studies reported the risk of all-cause mortality. Four studies assessed the risk of mortality from CVD and cancer. In total, 39 250 deaths were reported among 627 209 participants in a 7 to 18-year follow-up. A high consumption of soy products was not significantly associated with a lower risk of mortality from all-causes (HR: 0.96, 95% CI: 0.90, 1.02, I2: 38.5%, and Pheterogeneity = 0.14), CVD (HR: 0.95, 95% CI: 0.82, 1.10, I2: 49.9%, and Pheterogeneity = 0.07), and cancer (HR: 0.98, 95% CI: 0.92, 1.05, I2: 0%, and Pheterogeneity = 0.75). These findings indicated no significant association between a high intake of soy products and all-cause, CVD, and cancer mortality. Further studies are needed to clarify the association between the types of soy products and the risk of mortality.