Table 2.
A brief summary of current evidence of studies regarding the preventive and therapeutic effects of isoflavones and soyfoods.
| Studies (Ref. No.) | Study Design | Contents | Main Preventive (P) and Therapeutic (T) Effects | |
|---|---|---|---|---|
| Hot flushes | ||||
| [32] St Germain | randomized controlled trial (RCT) | soy | T | no difference |
| [33] Tice | RCT | isoflavone tablets | T | no difference |
| [35] Cancellieri | RCT | isoflavone from herbal supplement | T | isoflavones more effective than placebo |
| [34] Cheng | prospective study | isoflavones extracted from soya bean | T | isoflavones more effective than placebo |
| [16] Welty | RCT, crossover | soy nut | T | soy more effective than placebo |
| [36] Thomas | systematic review | natural vs. synthetic isoflavones | T | synthetic or combination isoflavones more effective than natural soy |
| [37] Washburn | randomized crossover trial | soy protein | T | soy protein more effective than placebo |
| [38] Khaodhiar | RCT | daidzein-rich isoflavone aglycones | T | daidzein-rich isoflavone aglycones more effective than placebo |
| [39] Cianci | observational prospective study | calcium, vitamin D3, inulin, soy isoflavones | T | soy supplement + inulin effective |
| [40] Carmignani | RCT | soy vs. hormone replacement therapy (HRT) | T | HRT more effective than soy; both are superior to placebo |
| [41] Bolanos-Dıaz | meta-analysis | soy extracts vs. HRT | T | HRT more effective than soy extracts; both are superior to placebo |
| [42] Amato | multicenter RCT | aglycone hypocotyl soy isoflavone | T | no difference |
| [43] Daily | systematic review, meta-analysis | soy isoflavone and equol | T | equol or isoflavone in equol-producers more effective than placebo |
| [28] Newton | observational study | equol-producer status | T | soy in equol-producers more effective than non-producers |
| [19] Lambert | RCT | red clover extracts | T | red clover extracts more effective than placebo |
| Hormone-related osteoporosis | ||||
| [45] Ma | meta-analysis | isoflavone | T | increase spinal bone mineral density (BMD) |
| [42] Amato | multicenter RCT | aglycone hypocotyl soy isoflavone | T | slow BMD loss |
| [44] Lambert | systematic review and meta-analysis | isoflavone aglycone | T | preserve BMD |
| Urogenital tract | ||||
| [48] Reed | RCT | black cohosh or dietary soy | T | no effect on vaginal cytology |
| [46] Waetjen | prospective cohort study | dietary intake of isoflavones | T | no effect on stress or urge incontinence |
| [49] Vitale | prospective, randomized, placebo-controlled study | isoflavones, calcium, vitamin D, inulin | T | May improve sexual function |
| [50] Ribeiro | RCT | isoflavone | T | failed to yield an estrogenic effect on the urogenital tract and to relieve the vulvovaginal symptoms |
| Metabolic syndrome | ||||
| [51] Stuenkel | randomized clinical trial | isoflavone supplements | T | loss of weight and fat mass, but interpretation difficult |
| [52] Mueller | in vitro study | PPARγ binding and transactivational activity | T | red clover extracts may be used to treat metabolic syndrome |
| Cardiovascular disease | ||||
| [53] van der Schouw | prospective study | food phytoestrogens | P | low dose phytoestrogen not protective |
| [54] Nestel | randomized crossover trial | purified soybean extract | T | may improve systemic arterial compliance |
| [34] Cheng | prospective study | isoflavones extracted from soya bean | T | no difference in lipoprotein lipids |
| [56] Wong | RCT | soy hypocotyl isoflavones | T | no effect on nitric oxide metabolism or blood pressure |
| [57] Suparto | animal study | soy protein | T | HRT + soy harmful, soy or HRT not beneficial |
| [58] Sathyapalan | double-blind randomized study | soy protein +/− soy isoflavone | T | soy protein with isoflavones improved cardiovascular markers compared to soy protein alone |
| [59] Ma | 3 prospective cohort studies | isoflavones, tofu and soymilk | P | higher intake of isoflavones and tofu was associated with a moderately lower risk of developing coronary heart disease |
| Cognitive function and neuromuscular systems | ||||
| [61] Clement | systematic review | isoflavones and soy | T | may improve cognition |
| [60] Greendale | cohort study | dietary phytoestrogens | T | better processing speed but worse verbal memory |
| [62] Miyake | cross-sectional study | soy products and isoflavones | T | independent inverse relationships between intake of soy products and isoflavones and depressive symptoms during pregnancy |
| [63] Tabata | animal study | isoflavone aglycone | T | significantly modulated muscle atrophy after denervation in mice, probably due to the decrease in apoptosis-dependent signaling |
| Cancer risk | ||||
| [67] Hirose | case-control study | soy products as part of daily intake | P | lower risk of breast cancer in premenopausal women |
| [68] Alipour | case-control study | soy extracts | soy extracts may cause benign changes in breast | |
| [71] Kang | cohort study | dietary intake of soy isoflavones | P | lower recurrence of estrogen- and progesterone-receptor positive breast cancers receiving anastrazole therapy after surgery |
| [76] Shin | case-control study | dietary soyfood and isoflavone intake | P | reduced risk for overall colorectal cancer |
| [70] Zhao | meta-analysis | soy foods | P | a high dietary intake of soy foods may reduce breast cancer risk |
| [72] Budhathoki | prospective study | soy food and isoflavone | were not associated with the risk of endometrial cancer. | |
| [73] Quaas | double-blind RCT | isoflavone soy protein | no effect on the rates of endometrial hyperplasia and cancer | |
| [74] Ollberding | prospective study | isoflavone, daidzein and genistein intake | P | are associated with a reduced risk of endometrial cancer |
| [75] Wada | population-based prospective study | total soy and isoflavones | P | are associated with a decreased risk of bladder cancer |