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Effect of S-equol and Soy Isoflavones on Heart and Brain

[ Vol. 15 , Issue. 2 ]

Author(s):

Akira Sekikawa*, Masafumi Ihara, Oscar Lopez, Chikage Kakuta, Brian Lopresti, Aya Higashiyama, Howard Aizenstein, Yue-Fang Chang, Chester Mathis, Yoshihiro Miyamoto, Lewis Kuller and Chendi Cui   Pages 114 - 135 ( 22 )

Abstract:


Background: Observational studies in Asia show that dietary intake of soy isoflavones had a significant inverse association with coronary heart disease (CHD). A recent randomized controlled trial (RCT) of soy isoflavones on atherosclerosis in the US, however, failed to show their benefit. The discrepancy may be due to the much lower prevalence of S-equol producers in Westerners: Only 20-30% of Westerners produce S-equol in contrast to 50-70% in Asians. S-equol is a metabolite of dietary soy isoflavone daidzein by gut microbiome and possesses the most antiatherogenic properties among all isoflavones. Several short-duration RCTs documented that soy isoflavones improves arterial stiffness. Accumulating evidence shows that both atherosclerosis and arterial stiffness are positively associated with cognitive decline/dementia. Therefore, potentially, soy isoflavones, especially S-equol, are protective against cognitive decline/dementia.

Methods/Results: This narrative review of clinical and epidemiological studies provides an overview of the health benefits of soy isoflavones and introduces S-equol. Second, we review recent evidence on the association of soy isoflavones and S-equol with CHD, atherosclerosis, and arterial stiffness as well as the association of atherosclerosis and arterial stiffness with cognitive decline/ dementia. Third, we highlight recent studies that report the association of soy isoflavones and S-equol with cognitive decline/dementia. Lastly, we discuss the future directions of clinical and epidemiological research on the relationship of S-equol and CHD and dementia.

Conclusions: Evidence from observational studies and short-term RCTs suggests that S-equol is anti-atherogenic and improves arterial stiffness and may prevent CHD and cognitive impairment/ dementia. Well-designed long-term (≥ 2years) RCTs should be pursued.

Keywords:

S-equol, soy isoflavones, atherosclerosis, arterial stiffness, coronary heart disease, cognitive decline, cognitive impairment, dementia.

Affiliation:

Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, National Cerebral and Cardiovascular Center, Suita, Osaka, Department of Neurology, University of Pittsburgh, Pittsburgh, PA, National Cerebral and Cardiovascular Center, Suita, Osaka, Department of Radiology, University of Pittsburgh, Pittsburgh, PA, National Cerebral and Cardiovascular Center, Suita, Osaka, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, Department of Radiology, University of Pittsburgh, Pittsburgh, PA, National Cerebral and Cardiovascular Center, Suita, Osaka, Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA

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