Dietary soybean isoflavones in Alzheimer's disease prevention.

Soybean isoflavone (SIF) is a type of polyphenol present extensively in legumes. Because of its unique chemical construction and the physiological activity of the phenolic hydroxyl group, SIF exhibits strong antioxidant activity in antioxidant and nonantioxidant enzyme systems. Genistein is the major isoflavone in soy foods, accounting for more than 50% of the isoflavone content. The health effects of soybean dietary isoflavones on humans have gained increased attention. Recent studies have suggested that SIF may alleviate neurodegenerative diseases such as Alzheimer's disease (AD). Despite the comprehensive research on AD, effective treatments for AD are yet to be established. The early diagnosis and prevention of mild cognitive impairment (MCI) have become crucial for delaying AD development. Several dietary polyphenols have exerted cognitive effects on AD, and the appropriate intake of dietary SIF helps reduce the risk of AD. This study reviews the possible mechanisms of AD pathogenesis and their relationships with SIF intake; the results provide useful insights for AD prevention in the future.