Does phytoestrogen supplementation improve cognition in humans? A systematic review

Abstract

Recent evidence indicates that resveratrol, a phytoestrogen, can improve cognitive function in postmenopausal women by enhancing cerebral vasodilator responsiveness. We examine the effects of phytoestrogen supplementation on cognition and compare resveratrol with other phytoestrogens. Databases were searched for reports of randomized controlled trials (RCTs) containing terms describing phytoestrogens together with terms relating to cognition. Effect sizes were determined for changes in cognition. We identified 23 RCTs, 15 with isoflavone and eight with resveratrol or grape formulations. Six soy isoflavone studies showed positive cognitive effects of medium size. Greater benefits were seen in women who were <10 years postmenopausal and supplemented for <6 months. Small-to-medium effect-size cognitive benefits of resveratrol were seen in four studies of older adults of mixed gender and in postmenopausal women who took 150-200 mg resveratrol daily for at least 14 weeks. No benefits were seen in three studies using red clover or grape formulations. Supplementation with either soy isoflavone or resveratrol improved executive function and memory domains of cognitively normal older adults in half of the included studies, mostly with medium effect sizes. The cognitive benefit of resveratrol was related to improved cerebral perfusion.

Estrogen Interactions With Lipid Rafts Related to Neuroprotection. Impact of Brain Ageing and Menopause

“…Isoflavones are abundant in soybean products (e.g., tofu), and resveratrol is highly abundant in grape skin and berries. Interestingly, some evidence indicates that supplementation with either isoflavones or resveratrol to menopausal women in early stages (<10 years) show some beneficial effects in memory and cognition, as well as improved cerebral vascularization (Evans et al, 2016 ; Thaung Zaw et al, 2017 ).…”

Soy and Isoflavone Consumption and Multiple Health Outcomes: Umbrella Review of Systematic Reviews and Meta‐Analyses of Observational Studies and Randomized Trials in Humans

“…Soy isoflavone supplementation seems to have a positive effect on improving summary cognitive function and visual memory in postmenopausal women . Greater benefits were seen in women who are less than 10 years postmenopause and supplemented for less than 6 months . The dose and duration efficacy was found to be 60–116 mg per day for at least 12 weeks .…”

“…Greater benefits were seen in women who are less than 10 years postmenopause and supplemented for less than 6 months . The dose and duration efficacy was found to be 60–116 mg per day for at least 12 weeks . Soy was also found to have a beneficial effect on depression and anxiety in menopausal women …”

Is There Such a Thing as “Anti-Nutrients”? A Narrative Review of Perceived Problematic Plant Compounds

“…It is hypothesized that regular consumption of isoflavone-rich foods provides substrates for equol producing bacteria to thrive, if present [ 123 ]. There are many suggested health benefits of phytoestrogens, including reduced menopausal symptoms, reduced risk of cardiovascular disease, obesity, metabolic syndrome, type 2 diabetes, cognitive disorders, and various forms of cancer [ 124 , 125 , 126 , 127 , 128 ]. Nonetheless, concerns are frequently raised that soy isoflavones and other phytoestrogens may act as endocrine disruptors and stimulate the growth of estrogen-sensitive cancers [ 129 , 130 , 131 , 132 ].…”