Objectives: To determine the efficacy of chicken essence for improving cognitive performance.
Material and method: English language database including Embase, Medline, PsychINFO and Global Health (up to May 2014) were searched. Inclusion criteria were randomized double-blind controlled studies (RCT) or cross-over studies comparing chicken essence with placebo.
Results: Four trials were included. Three studies measured cognitive performance, while the remaining study assessed cognitive performance after fatigue-inducing tasks. When compared to placebo, chicken essence improved arithmetic (SMD -1.23, 95% CI -2.51 to -0.31) and memory (SMD -3.94, 95% CI -4.59 to -3.29). There were no ascertainable positive effects on attention/concentration (SMD -1.55, 95% CI -4.77 to 1.67), anti-fatigue (SMD 1.20, 95% CI 0.53 to 1.88), and recovery from mental fatigue (SMD -0.38, 95% CI -1.0 to 0.25). However, the levels of evidence with respect to each cognitive domain was rated as ‘very low’ using the GRADE system because of low sample size, inconsistency and high risk of bias.
Conclusion: There are few trials examining the efficacy of chicken essence to cognitive performance. Furthermore, the level of evidence was very low. Using it for this indication is not suggested at present. Additional high quality RCT designs are needed to arrive at a stronger conclusion.