The beneficial efficacy of soy is often attributed to the presence of isoflavones, capable of mitigating the excesses of endogenous estrogens, through the competition with estrogen receptors or by the activation of receptors, in the presence of low levels of endogenous estrogens. The detailed selection process is highlighted in Fig. Any later it delays ovulation. However, the number of combined participants of the two studies was very limited (n: 40). hasContentIssue true, Proposed mechanisms of isoflavones action, This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (, Copyright The Author(s), 2022. There was a significant correlation between dietary soy consumption and fertilisation rate (77% v. 71%, P=0004), age-adjusted pregnancy (52% v. 41%, P=003) or age-adjusted live birth rate (44% v. 31%, P=0007) among soy consumers compared with non-consumers. Independent Researcher, Via Venezuela 66, 98121Messina, Italy, Laboratory of Cardiovascular Endocrinology, IRCCS San Raffaele Roma, 00166Rome, Italy, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, 00166Rome, Italy, Center for Complementary Medicine, Department of Internal Medicine II, Faculty of Medicine, University of Freiburg, Freiburg, Germany, Reference Mosallanezhad, Mahmoodi and Ranjbar, Reference Setchell, Brown and Lydeking-Olsen, Reference Hamilton-Reeves, Vazquez and Duval, Reference Reed, Camargo and Hamilton-Reeves, Reference Oyawoye, Abdel Gadir and Garner, Reference Mumford, Sundaram and Schisterman, Reference Jacobsen, Jaceldo-Siegl and Knutsen, Reference Crawford, Pritchard and Herring, Reference Andrews, Schliep and Wactawski-Wende, Reference Sdergrd, Bckstrm and Shanbhag, Reference Escobar-Morreale, Luque-Ramrez and Gonzlez, Reference Showell, Mackenzie-Proctor and Jordan, Reference Romualdi, Costantini and Campagna, Reference Chavarro, Mnguez-Alarcn and Chiu, Reference Sinai, Ben-Avraham and Guelmann-Mizrahi, Reference Ropero, Alonso-Magdalena and Ripoll, Reference Valles, Dolz-Gaiton and Gambini, Reference Gunnarsson, Ahnstrm and Kirschner, Soy, soy foods and their role in vegetarian diets, Consumption of soy foods and isoflavones and risk of type 2 diabetes: a pooled analysis of three US cohorts, Cumulative meta-analysis of the soy effect over time, Soy, soy isoflavones, and protein intake in relation to mortality from all causes, cancers, and cardiovascular diseases: a systematic review and dose-response meta-analysis of prospective cohort studies, Consensus: soy isoflavones as a first-line approach to the treatment of menopausal vasomotor complaints, Soy isoflavones for osteoporosis: an evidence-based approach, 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 intake is associated with lowering blood pressure in adults: a systematic review and meta-analysis of randomized double-blind placebo-controlled trials, The antioxidant role of soy and soy foods in human health, Non-isoflavone phytochemicals in soy and their health effects. However, even in the West, it is currently widely used, especially due to its versatility in plant-based products for health purposes and vegetarian diets (Reference Rizzo and Baroni 1).Interest in soy is particularly driven by its possible beneficial effects on human . Notably, these latter compounds are present in several foods such as legumes, cereals and seeds, whereas soy is almost the only source of isoflavones in human diet. A total number of twenty-two experimental articles plus a meta-analysis was used for the final synthesis. Furthermore, there was no evaluation of metabolic utilisation capacity of isoflavones and their absorption by measuring serum and urinary levels. The dietary intake of isoflavones did not appear to be associated with fertility in the two cohorts but some marginal evidence of amelioration of fertility was related to a higher intake of isoflavones among 30 years old individuals after age stratification (Fecundability Ratios: 112, 95% CI 994, 134 and 119, 95% CI 092, 155 in the two cohorts comparing 90th with <24th percentile). In addition to the interventional study by Kohama and colleagues, we found three longitudinal cohort observational studies(Reference Jarrell, Foster and Kinniburgh36,Reference Mumford, Sundaram and Schisterman39,Reference Wesselink, Hatch and Mikkelsen44) and a cross-sectional study(Reference Jacobsen, Jaceldo-Siegl and Knutsen38) that investigated the association between soy and fertility. This, in turn, stimulates ovulation and can make you ready for pregnancy. The authors showed an inverse correlation between cycle length (detected via fertility monitors and daily journals) and total urinary phytoestrogen levels (0042d for 10% increase, 95% CI 0080, 0003). The study included the evaluation of patients microbiota composition as the primary endpoint, but androgen levels were also evaluated with AMH as markers of fertility as a secondary endpoint. No significant differences were appreciated for free testosterone and DHEAS. Sampling involved synchronisation on the third day of menstrual cycle follicular phase, spontaneous or pharmacologically induced. The adjustment for male partner intake of soy in the subgroup analysis did not change the association. This is justified by the fact that the study was not designed for the specific assessment of dietary soy concerning fertility-related outcomes. This phenomenon highlights how in literature there is greater attention to phytoestrogens and their effect, frequently underestimating the role of other components that have a marginal interest. On the other hand, many perplexities have been raised about possible negative mechanisms leading to endocrine disruptor effects(Reference Bar-El and Reifen20). The article processing charge was funded by the Baden-Wuerttemberg Ministry of Science, Research and Art and the University of Freiburg in the funding programme Open Access Publishing. Qin, Zhen However, soy intake did not correlate with cycle length (r: 012, P=045). In response, your body starts a cascade of events to boost estrogen production. There was no relationship between isoflavone intake and reported problems becoming pregnant. Soy is a key food in human nutrition. This effect persisted for at least one menstrual cycle after the suspension of soy intake, with a maximum of persistence for three menstrual cycles. After 6 months, estradiol levels of patients in the intervention group were higher compared with basal (P<005), whereas luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were unchanged. The influence on SHBG levels can have a beneficial effect from an endocrine point of view, without negative effects on ovulation. View all Google Scholar citations Soy isoflavones have repeatedly shown a mild estrogenic effect but at high concentrations they may have enough power to act on hypothalamus and pituitary gland, reducing the ovarian synthesis of estrogens. However, this omission does not necessarily imply that the assessment has not been carried out. The effects obtained from selected studies do not seem to show a clear significance regarding fertility and menstrual cycle length, as discussed in the previous paragraph. While the observational data better reflect the effects of diet in free-living conditions compared with experimental settings of clinical trials, the use of food frequency questionnaires exposes to possible misclassification and measurement errors. Soy consumption is supposed to have protective effects against cardiovascular disease by cholesterol-lowering and blood pressure improvement action and in the prevention of cancer or diabetes and it also supports bone health and the management of menopause symptoms(Reference Ding, Pan and Manson2Reference Mosallanezhad, Mahmoodi and Ranjbar8). Compliance with the intervention was suggested by urinary excretion of isoflavones. Main cellular mechanism for isoflavones. The study must be considered exploratory, because of the limited number of luteal phase deficiency cycles and a small number of fertility-related outcomes. 1. The authors highlighted a marginal reduction of luteal phase in the adjusted multivariable model for an increase of 10mg/d of dietary isoflavones (aOR: 138, 95% CI 099, 192, P=006), identified by monitoring LH levels in urine by a fertility monitor and 4-d per cycle 24-h dietary recalls. Corrections for confounding factors, such as diet, demographics, lifestyle factors, age, body composition and ethnicity, indicated reliable analysis. The use of urinary phytoestrogens and their metabolites is a more reliable system compared to the evaluation of dietary intake. Recently, in a prospective study by Levine et al., 326 American women eumenorrheic aged 1840 were followed for 12 months or until pregnancy(Reference Levine, Kim and Purdue-Smithe45). Isoflavones in human plasma are usually low (04157nM) in individuals consuming low-isoflavone diets but in large soy-consumers, such as Asian people, isoflavone concentration can reach up to ~4M, with equol reaching up to ~40nM in low consumers and up to ~2M in large soy-consumers(Reference Morton, Arisaka and Miyake88). These aspects considerably reduce the reliability of results, favouring data misinterpretation. (Reference Filiberto, Mumford and Pollack37). Since there are no scientific studies on the effects of soy isoflavones and ovulation, these are just general guidelines. However, the work had several strengths: the real evaluation of luteal and follicular phase through the dosage of urinary LH:creatinine ratio, the characterisation of sampling according to the cycle; the evaluation of isoflavone content in foods used for the intervention and quantification of urinary isoflavones to check compliance; the use of soy foods and not supplements or extracts to approach a real-life pattern; the characterisation of diet at various steps of clinical trial to avoid confounding mechanisms; the stratification by ethnicity which indirectly showed the effect on equol-producer individuals. Although some works investigate the relationship between consumption of soy formulations in infancy and age at menarche, as well as the onset of puberty or pre-puberty reproductive organ size, these outcomes are not strictly related to fertility in reproductive age(Reference Andres, Moore and Linam69Reference Sinai, Ben-Avraham and Guelmann-Mizrahi71). The present paper aims to conduct a review of available data on the effect of soy, soy foods and soy components on women's fertility and related outcomes. The reduction of estradiol and progesterone could postpone ovulation by lengthening the menstrual cycle. and Polycystic ovary syndrome (PCOS) is a major endocrine and metabolic disorder in women(Reference Meier62,Reference Liu, Zhang and Shi63) . Published by Cambridge University Press on behalf of The Nutrition Society. between 128 women fed with soy-based formula and 268 women fed with cow milk formula during infancy. Furthermore, the type of dietary survey carried out in the proposed environmental questionnaire was not clear. They may be useful in alleviating menopause symptoms or preventing osteoporosis in postmenopausal women. 2022. For example, it should be identified whether the interest is related to pharmacological effect, thus implying the use of high concentrations of soy components, or if the aim is to investigate soy functional effects that can be obtained mimicking eating habits, thus providing soy foods with realistic intake levels. The same authors admitted that they had no information on the type of soy used and about the last ingestion. The evaluation at two different times of menstrual cycle allowed to discriminate the effect between luteal and follicular phases but not day by day hormonal fluctuations. The consumption of soy over time, the possible use of certain foods considered healthy in seeking pregnancy or the willingness to avoid pregnancy could generate spurious associations. [1] Similar significant association was observed for peak luteal progesterone 10ng/ml (aOR: 140, 95% CI 100, 196, P=005). Steroid hormones (estradiol, progesterone and DHEAS) play a role in epithelial cell proliferation in mammals. Furthermore, even at high concentrations, they did not show a clear influence on fertility. The authors defined the unusual estradiol increase as erratic. Regarding the observational studies available, in 2015 Venegas et al. You should take them like Clomid hun so cd 1-5, 2-6, 3-7, 4-8 or 5-9. It is important to evaluate the levels of hormones that fluctuate during the cycle at several points. The phytoestrogen actions of soy isoflavones may increase estrogen levels in the body and induce ovulation in women, thus, may speed up the process of pregnancy. The disease etiology is still debated but it seems to involve inflammatory mechanisms and oxidative stress(Reference Escobar-Morreale, Luque-Ramrez and Gonzlez65,Reference Showell, Mackenzie-Proctor and Jordan66) . The authors of this recent literature review of available evidence from observational and interventional studies concluded that soy and its components cannot be classified as an endocrine disruptor. It does not appear to be randomised and blinded, but the nature of outcomes should not be affected by these limitations. Day 22 should correspond to the mid-luteal phase, however, the authors pointed out that participants exhibited different lengths of menstrual cycle and this could have been a source of heterogeneity that was used as a covariate in the regression model. In another clinical trial already discussed, although no changes in cycle length were found following soy foods intervention in twenty women with a follow-up of at least seven menstrual cycles, a significant reduction in follicular phase by 93% (P<005) in estradiol concentrations was observed, but not in luteal phase(Reference Wu, Stanczyk and Hendrich28). The small number of participants significantly limited the quality of results. Pending further confirmation, soy and its components do not appear to have a clinically relevant influence on menstrual cycle in healthy women. Among the six women in the first clinical trial(Reference Lu, Anderson and Grady26), the intervention with soy also led to a significant reduction in dehydroepiandrosterone sulphate (DHEAS) levels (23%, P=003), an intermediary in estradiol synthesis. Published online by Cambridge University Press: The Adventist Church is a community with very homogeneous habits and a high prevalence of vegetarians (54% lacto-ovo vegetarian and 7% vegan from this study)(Reference Kent, Morton and Ward51,Reference McBride, Bailey and Landless52) . Among selected prospective cohort studies, in 2012 Jarrell and colleagues conducted an observational study of 323 Canadian women with late pregnancy (aged at least 35) followed from the second month of pregnancy until delivery(Reference Jarrell, Foster and Kinniburgh36). Furthermore, the possible ameliorative influence of soy or its components in the case of assisted reproduction techniques outcomes and pregnancy seeking appears promising and worthy of interest. View the latest deals on Natrol Menopause Support Supplements. Several studies and case-reports describing feminizing effects including lowering testosterone levels and raising estrogen levels in men have been published. Shop Soy Isoflavones Menopause Relief and read reviews at Walgreens. The ethnicity assessment of participants was useful in identifying, as might be expected, a greater consumption of soy foods by Asian individuals. Fig. The clinical trial was limited to a small sample size, lacking of control/placebo group and there was no characterisation of equol-competence. The soy isoflavones block the estrogen receptors in your brain and fool your body into thinking its natural estrogen levels are low. Publication types Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't MeSH terms The sooner you take it the more eggs start to mature and the later it focuses on the quality of the most maturing egg, or at least this is what I read. The study involved a large number of couples seeking pregnancy. Guo, Tingting Find company research, competitor information, contact details & financial data for Lucky Twins Distribution of Rancho Cucamonga, CA. Unfortunately, the work of Kohama et al. This was a short pilot study with a small sample size in subgroups. The standard guidelines for Clomid are to take it either on cycle days 3-7 or 5-9. Main characteristics of selected studies. Although isoflavones can be found in many foods, not soy foods can be considered negligible sources of these compounds. The authors declare that they have no conflicts of interest. Go. Jia, Liyan This could have introduced other confounding factors such as the influence of male on couple's fertility or possible changes in habits caused by the desire to conceive. . However, levels of progesterone, estradiol, free estradiol, estrone and SHBG did not show significant differences. However, the intake of isoflavones in diet has not been investigated, and therefore, it was not possible to define the presence of equol-producers among participants. Despite adjustments for demographic, lifestyle, dietary factors, including ethnicity and other phytoestrogens, it would have been useful to check the dietary intake of isoflavones for equol-producers evaluation. DPO you got your BFP: 14dpo. Isoflavones also bind to ER receptor, albeit with lower affinity. 2023. FSH levels were not significantly changed after genistein intervention. Moreover, couples with male infertility issues were excluded. was a pilot study without a characterisation of diet among participants and without data on soy composition (isoflavone or antioxidant contents). Recently, the anti-Mllerian hormone (AMH) concentrations have proved to be a useful tool for predicting female fertility, especially because it is independent of the cycle phase(Reference Dewailly and Laven48). However, the association between soy and isoflavones with the reduction of luteal phase seems weak. Overall, a trend toward improvement can be appreciated but further studies are necessary to confirm the beneficial effect. Based on our literature search, we also identified two observational studies: a cross-sectional study published in 1997 by Nagata et al. However, ethnicity was not used for outcomes stratification.