Green, Eulalee 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. Conclusions: These data suggest that higher intake of soy foods and soy isoflavones is associated with lower sperm concentration. Furthermore, the search for sources has been extended to the single manuscripts reference lists. In 2015, a longitudinal study found no differences in sexual organ development at 5 years of age between cow milk formula, breast milk and soy formula feeding(Reference Andres, Moore and Linam69). Regarding the observational studies available, in 2015 Venegas et al. This was a short pilot study with a small sample size in subgroups. Romualdi and colleagues in 2008 enrolled twelve Italian women with metabolic syndrome and PCOS and with a follow-up of 6 months using 36mg/d of oral genistein as an intervention(Reference Romualdi, Costantini and Campagna34). To our knowledge, this is the first comprehensive review on soy effect on women's fertility. However, after removing data from studies with elevated bias risk, two studies were included in the sensitivity analysis with a consequent loss of statistical significance for LH levels. SMART [Internet]. The two observational studies also show different limitations, in particular, one of these studies uses a follow-up of only 2 months. The study must be considered exploratory, because of the limited number of luteal phase deficiency cycles and a small number of fertility-related outcomes. However, for articles selection, we used search engines both for scientific literature and specific for clinical trials, without filters application that could have limited the results. Similar significant association was observed for peak luteal progesterone 10ng/ml (aOR: 140, 95% CI 100, 196, P=005). 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. Furthermore, hormone levels were evaluated only at baseline, without taking into account the differences between the two groups. Similarly, the stratification by ethnicity and equol-producers may suggest the nature of interactions between soy and fertility. Phytoestrogens and breast cancer promoters or protectors? Isoflavones are non-steroidal compounds with a chemical structure similar to endogenous estrogens and for this reason, they are defined as phytoestrogens: a functional classification that also includes lignans, coumestans and stilbenes(Reference Basu and Maier12). Furthermore, the use of spot urine samples for BPA quantification may have underestimated its exposure. Regarding observational studies, in 2015 Andrews and colleagues conducted a prospective cohort study on 246 American women with normal menstrual cycle, aged 1844 and with 13% of participants of Asian ethnicity, for a follow-up of 12 whole menstrual cycles(Reference Andrews, Schliep and Wactawski-Wende41). Han, Jing SHBG levels were not associated with the intake of soy foods, except in the case of miso intake on the 22nd day of cycle (r: 036, P=002). Nevertheless, these studies often suffer difficulties in evaluating individual effectiveness as well as in identifying possible confounding factors and population characteristics (ethnicity, health conditions, equol-competence, etc.). Qin, Zhen Fertility is defined by the number of offspring produced by an individual. CA. Isoflavones are produced via a branch of the general phenylpropanoid pathway that produces flavonoid compounds in higher plants. Meanwhile, the possible influence on endocrine system, in particular by isoflavones, raised concerns among some researchers. Consequently, it is plausible that research efforts have been aimed at evaluating the effects of soy, especially isoflavones, on human fertility and hormonal regulation. Soy Isoflavones supplements and Fertility Infertility is a condition that prevents pregnancy despite having regular sexual intercourse with your partner for at least a year. Isoflavones also show effects that do not imply ER and ER involvement. However, because of the paucity of studies exploring the impact of soy intake on women's fertility, as well as the limited population sample size, the frequently incomplete specimens collection to investigate all cycle phases and the insufficient characterisation of participants, the evidence is suggestive and it needs further in-depth research taking into account all these aspects. Such shorter menstrual cycle length seemed not clinically relevant because shorter than 1d. Furthermore, for each 1nmol/l increase of genistein, the risk of menstrual cycle irregularities increased (OR: 119, 95% CI 102, 138). Main characteristics of selected studies. Soy is a very popular food and its consumption is part of the traditional cuisine of South-East Asian countries. 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. Clinical trials can provide solid causal inferences, but they often have limitations in terms of study duration or intervention design. 1 The FDA based this decision on clinical studies showing that at least 25 g of soy protein per day lowered . 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. Why did you take Soy Isoflavones: I had tried most other things so decided to be a guinea pig. From the analysis of urinary excretion of isoflavones normalised for creatinine during the intervention with soy, Asian women had significantly greater excretion of isoflavones than non-Asian women. 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). Luteal phase deficiency can represent a relevant aspect for pregnancy outcomes and fertility disorders. Put simply, most of the evidence indicates that isoflavones do not adversely affect men's fertility. However, the association between soy and isoflavones with the reduction of luteal phase seems weak. This is justified by the fact that the study was not designed for the specific assessment of dietary soy concerning fertility-related outcomes. Soy can contain numerous other phytochemicals such as saponins, phytosterols, phytic acid, non-isoflavone flavonoids, peptides, protease inhibitors and other bioactive substances. Pettitt, Claire It is important to evaluate the levels of hormones that fluctuate during the cycle at several points. Researchers did not observe any clinical improvement, alteration of menstrual cycle or hormonal alteration (estradiol, SHBG, DHEAS, androstenedione, testosterone, FSH, LH) compared with baseline levels. After the intervention period, four patients became pregnant and twelve patients showed ovulation improvements based on ultrasonography (P<005). 44% of women of Asian descent were in the highest quartile of isoflavone intake. The concomitant treatment with soybean phytoestrogens significantly increased the implantation rate (254% v. 202%; P<005), the pregnancy rate (393% v. 209%; P<005) and the pregnancy-to-delivery rate (303% v. 162%; P<005) compared with placebo. Interest in soy is particularly driven by its possible beneficial effects on human health. For these reasons, studies that evaluated the ovarian hormones secretion were aimed at exploring the potential beneficial effect of soy on breast cancer prevention, but they were not designed for the evaluation of endocrine consequences, including fertility. Servier Medical Art. In response, your body starts a cascade of events to boost estrogen production. We have twins in the family and I like the thought, so a natural remedy would be nice :) "Isoflavones are polyphenolic compounds that are capable of exerting estrogen-like effects. Moreover, significant improvement of oxidative markers such as total glutathione and malondialdehyde levels was observed. United States California Eating Places. In both studies, the lowering of progesterone levels in luteal phase was also significant in the case of soy intake, mean 35% (P=0002) compared with baseline. How soy isoflavones help to induce ovulation Soy isoflavones have been found effective in inducing ovulation in women with irregular ovulation or anovulation. Among the studies already cited, however, we must consider the work of Kohoama and colleagues(Reference Kohama, Kobayashi and Inoue33), which showed fertility improvements following intervention with black soy extract in individuals with secondary amenorrhea, including patients with PCOS. In 2000, Wu et al. (Reference Moher, Liberati and Tetzlaff24). In particular, soy contains numerous non-isoflavone constituents such as phytic acid, triterpenes and sterols, BowmanBirk protease inhibitors, unsaturated fatty acids, saponins, inositol phosphates, proteins, peptides such as lunasin;(Reference Kang, Badger and Ronis10) nevertheless, soy isoflavones have attracted much attention in the last years for its estrogenic as well as non-hormonal properties(Reference Aulisa, Binda and Padua11). Many of its components show an antioxidant activity that can at least partially explain its effectiveness(Reference Rizzo9). Finally, twelve entries were identified and ten additional articles were obtained after the consultation of full-text bibliographic lists. 2023. The same type of soy phytoestrogen intervention was subsequently used by Unifer and colleagues in a second clinical trial on 213 infertile women undergoing in vitro fertilisation with embryo transfer cycles after intramuscular progesterone treatments (50mg/d) with or without (placebo) 1500mg/d of soy isoflavones intake(Reference Unfer, Casini and Gerli32). Using food frequency questionnaires, researchers found that women with high isoflavone intake ( 40 mg/day) had a 3% lower lifetime probability of giving birth to a live child compared to women with a low intake (< 10mg/day). Furthermore, considering soy as a mere source of isoflavones is extremely reductive. In the study by Nagata and colleagues, fifty Japanese women were enrolled to evaluate the association between soy intake (using an FFQ) and hormone levels. Corrections for confounding factors, such as diet, demographics, lifestyle factors, age, body composition and ethnicity, indicated reliable analysis. The generalisation of these results is complex due to the type of study, which does not allow to define a causal relationship. Soya Isoflavones and Vitamins The Group for those Using, Abusing and thinking about taking over the counter items to boost fertility. In the second study by Lu and colleagues(Reference Lu, Anderson and Grady29), ten American women aged 2342 who did not consume soy regularly were followed for the duration of a menstrual cycle, during which nutritional intervention with soy was performed (36 Oz/d soy drink; 113207mg/d IF), without observing significant changes in cycle length compared to baseline and with a marginal shortening of luteal phase (6%, P=007). The authors defined the unusual estradiol increase as erratic. Additional considerations regarding hormonal influences will be discussed in the next paragraph. In addition, no significant changes in progesterone, LH or SHBG were found in the whole study sample. In a logical perspective, the effect of soy cannot be attributed to the effect of its isoflavones alone. In addition, equol acts on incretins levels in endocrine L cell line GLUTag cells at concentration ranging from 50 to 300M, with long-term metabolic consequences(Reference Harada, Sada and Sakaguchi79). 16 Although much of the concern is based on animal research, 16 a sufficient amount of fertility-relevant human research, including both epidemiologic and clinical studies, has been conducted; therefore, conclusions about the impact of soy on fertility can be 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. 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