Do soy isoflavones improve cognitive function in postmenopausal women? A meta-analysis

Area of Science:

• Neuroscience
• Nutritional Science
• Gerontology

Background:

• Soy isoflavone (SIF) supplementation has been suggested to enhance cognitive function.
• Previous research findings on SIF's cognitive benefits in postmenopausal women are inconsistent.
• A quantitative synthesis is needed to clarify the effects of SIF on cognition in this demographic.

Purpose of the Study:

• To conduct a meta-analysis evaluating the efficacy of SIF supplementation on cognitive function in postmenopausal women.
• To quantify the overall effect and identify potential influencing factors such as age, geography, and treatment duration.

Main Methods:

• A systematic search of databases and websites was performed for relevant randomized controlled trials (RCTs) up to March 2014.
• Ten placebo-controlled RCTs involving 1,024 participants were included in the meta-analysis.
• Study quality was assessed using the Jadad scale and Cochrane's Risk of Bias Tool; standardized mean differences (SMDs) were calculated.

Main Results:

• The meta-analysis revealed a statistically significant overall positive effect of SIF supplementation on summary cognitive function scores (SMD = 0.08, P = 0.014).
• Significant improvements were observed in visual memory (SMD = 0.10, P = 0.016).
• Subgroup analyses indicated significant benefits in non-US countries, for women younger than 60 years, and with treatment durations under 12 months.

Conclusions:

• SIF supplementation appears to positively impact overall cognitive function and visual memory in postmenopausal women.
• Optimal timing for SIF intervention may exist, with age, geographical location, and treatment duration influencing outcomes.
• Further research should monitor long-term effects on neurodegenerative diseases and report adverse events.