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Meta-Analysis
. 2020 Feb 1;78(2):134-144.
doi: 10.1093/nutrit/nuz050.

Effects of soy isoflavones on cognitive function: a systematic review and meta-analysis of randomized controlled trials

Chendi Cui  1 , Rahel L Birru  2 , Beth E Snitz  3 , Masafumi Ihara  4 , Chikage Kakuta  4 , Brian J Lopresti  5 , Howard J Aizenstein  6 , Oscar L Lopez  3 , Chester A Mathis  5 , Yoshihiro Miyamoto  4 , Lewis H Kuller  1 , Akira Sekikawa  1
Affiliations
Meta-Analysis

Effects of soy isoflavones on cognitive function: a systematic review and meta-analysis of randomized controlled trials

Chendi Cui et al. Nutr Rev. .

Abstract

Context: The results of preclinical and observational studies support the beneficial effect of soy isoflavones on cognition.

Objective: This review aimed to evaluate the effects of soy isoflavones on cognition in adults.

Data sources: The PUBMED, EMBASE, Ovid Medline, Cochrane Library, and clinicaltrials.gov databases were searched.

Study selection: Two researchers independently screened 1955 records, using the PICOS criteria: participants were adults; intervention was dietary sources with soy isoflavones or isolated soy isoflavones; comparator was any comparator; outcome was cognitive function; study type was randomized controlled trials (RCTs). A third researcher was consulted to resolve any discrepancies. Sixteen RCTs were included and their quality assessed.

Data extraction: Information on study design, characteristics of participants, and outcomes was extracted. PRISMA guidelines were followed.

Data analysis: A random-effects meta-analysis was used to pool estimates across studies. In the 16 RCTs (1386 participants, mean age = 60 y), soy isoflavones were found to improve overall cognitive function (standardized mean difference [SMD], 0.19; 95% confidence interval [CI], 0.07-0.32) and memory (SMD, 0.15; 95%CI, 0.03-0.26).

Conclusion: The results showed that soy isoflavones may improve cognitive function in adults.

Systematic review registration: PROSPERO registration no. CRD42018082070.

Keywords: cognition; isoflavones; meta-analysis.

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Figures

Figure 1
Figure 1
Flow diagram of the literature selection process. Abbreviation: RCT, randomized controlled trial.
Figure 2
Figure 2
Overall standardized mean difference (SMD). The SMD with 95% confidence interval (CI) is displayed for each study. The weight was calculated using the inverse-variance weighting method. A random-effects model was used to calculate the summary SMD.
Figure 3
Figure 3
Standardized mean difference (SMD) for memory. The SMD with 95% confidence interval (CI) is displayed for each study. The weight was calculated using the inverse-variance weighting method. A random-effects model was used to calculate the summary SMD.
Figure 4
Figure 4
Subgroup analysis by duration, dose, age, region, and population. The SMD with 95% confidence interval (CI) was calculated for each subgroup. The P value was based on the Wald test.
See this image and copyright information in PMC

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