Habitual diets rich in phytoestrogens like isoflavones have been linked to a decreased incidence of hormone-dependent conditions such as breast cancer and menopausal complaints ^[1-5]. Despite the impressive scientific body of evidence that has been established over the past decades, some concerns have been raised over the estrogen-like effects of isoflavones that may exert a feminizing effect in men including reduced fertility. These concerns are based on published reports linking soy consumption in men to feminization ^[6] and reduced fertility ^[7-9] and are fuelled by studies indicating that isoflavones may affect sperm quality in vitro ^[10-14] and might impair reproductive health in animal studies ^[15-20]. However, animal studies mainly involved high soy diets leading to high serum levels of isoflavones and equol that far exceed those reached in humans consuming a typical Asian diet ^[20-21]. It is further well known that the negative effects of isoflavones on the reproductive system such as erectile dysfunction is due to a much higher rate of isoflavone metabolism in rodents compared to the human metabolism as well as the excessively high amount of isoflavones to which the animals were exposed ^[20].

 In 2002, a report was published and presented at the Fourth International Symposium on the Role of Soy in Preventing and Treating Chronic Disease ^[22]. In three intervention studies that were reviewed it was shown that in men consuming soyfoods or supplements containing 40–70 mg/d of soy isoflavones, minor effects on plasma hormones or semen quality were observed. The author concluded that these data do not support concerns about effects on reproductive hormones and semen quality. The intake levels from these studies are similar compared with those found in typical Asian diets ^[23].

An early review on the safety aspects concerning soy supplementation and men, published in 2003, presented an overview of clinical studies on soy isoflavones ^[24]. In this review, several short and long term studies on the effects on men were evaluated. In one study, six healthy male subjects were given an unrestricted diet supplemented with an intake of approximately 137 mg total isoflavones (aglycone equivalents). No significant changes in the metabolic pathways of soy isoflavones and no adverse effects were observed. In another longer-term study, no effects on endocrine function, including plasma estradiol concentrations, testicular volume and semen quality were reported in 14 healthy male volunteers consuming 40 mg aglycone isoflavones/d for 2 months. In a recent study, the effect of SoyLife 40 supplementation (116 mg aglycones/d) on the cognitive function of healthy men was investigated ^[25]. In this 12-week clinical study, the isoflavone supplements were well tolerated by the subjects and there were no adverse effects were reported.

 The concerns regarding possible feminizing effects of soy consumption in men are mainly based on three recent human studies ^{[6-7, 26]}. Two studies have described the possible feminizing effects of soy in two male individuals consuming excessive amounts of soy (as many as 14-20 servings per day) ^{[6, 26]}. Soyfoods consumption of this degree is considered abnormal and can, like nearly any other food, be expected to have negative effects on health. A more recent epidemiologic study investigated the relationship between soy consumption with fertility in sub-fertile men ^[7]. Although the soy consumption was associated with a reduced sperm concentration, there was no effect of soy intake on sperm morphology and motility. It should be noted that these results are in contrast with another similar study that reported that higher isoflavone intake was associated with levels of good sperm DNA integrity, sperm count and sperm motility ^[27]. Furthermore, one of the main weaknesses of the epidemiological study is that the researchers only looked at soy intake and no other dietary information was collected. It has been reported that different dietary factors such as supplementation with zinc and folic acid increase sperm count in fertile and infertile men, whereas a diet high in omega-6 fatty acids can have the opposite effect ^[28-29].

Furthermore, the concern regarding male fertility is based on the hypothesis that environmental estrogens might play a role in the observed decline of male fertility over the past decades ^[30-33]. The negative association between soy consumption and sperm concentration reported in the epidemiological study by Chavarro et al. (2008) ^[7], however, appear to follow the general trend of declining male fertility and this trend was not taken into account.

In contrast to the three human studies investigating association between soy isoflavone consumption and male fertility , a recently published (2010) review^[20] and meta-analysis^[34] discussed the clinical evidence related to the effect of soy isoflavones on the reproductive system in men, including the above mentioned reports. It was concluded that neither soyfoods nor isoflavones affect semen or sperm, or the levels of the male sex hormone, testosterone. It was generally concluded that soyfoods do not exert feminizing effects and that there was no clinical evidence that men’s fertility is negatively affected by soyfoods or isoflavones. It is generally advised that men can feel confident in making soy a part of their diet and that this will not compromise their virility or reproductive health.

References

 [1]          K. D. R. Setchell, Phytoestrogens: The biochemistry, physiology, and implications for human health of soy isoflavones, Am. J. Clin. Nutr. 1998, 68.

[2]           H. T. Adlercreutz, Phytoestrogens. State of the art, Environ. Toxicol. Pharmacol. 1999, 7, 201-207.

[3]           M. J. Messina, Legumes and soybeans: Overview of their nutritional profiles and health effects, Am. J. Clin. Nutr. 1999, 70, 439S-450S.

[4]           D. M. Tham, C. D. Gardner, W. L. Haskell, Potential health benefits of dietary phytoestrogens: A review of the clinical, epidemiological, and mechanistic evidence, J. Clin. Endocrinol. Metab. 1998, 83, 2223-2235.

[5]           T. Usui, Pharmaceutical prospects of phytoestrogens, Endocr. J. 2006, 53, 7-20.

[6]           J. Martinez, J. Lewi, An Unusual Case of Gynecomastia Associated with Soy Product Consumption, Endocrin. Pract. 2008, 14, 415-418.

[7]           J. E. Chavarro, T. L. Toth, S. M. Sadio, R. Hauser, Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic, Human. Reprod. 2008, 23, 2584-2590.

[8]           R. M. Sharpe, Lifestyle and environmental contribution to male infertility, Br. Med. Bull. 2000, 56, 630-642.

[9]           M. C. L. West, L. Anderson, N. Mcclure, S. E. M. Lewis, Dietary oestrogens and male fertility potential, Hum. Fertil. 2005, 8, 197-207.

[10]         D. Anderson, T. E. Schmid, A. Baumgartner, E. Cemeli-Carratala, M. H. Brinkworth, J. M. Wood, Oestrogenic compounds and oxidative stress (in human sperm and lymphocytes in the Comet assay), Mutation Research/Reviews in Mutation Research 2003, 544, 173-178.

[11]         Y.-C. Chen, M. L. Nagpal, D. M. Stocco, T. Lin, Effects of genistein, resveratrol, and quercetin on steroidogenesis and proliferation of MA-10 mouse Leydig tumor cells, J. Endocrinol. 2007, 192, 527-537.

[12]         S. A. Adeoya-Osiguwa, S. Markoulaki, V. Pocock, S. R. Milligan, L. R. Fraser, 17β-Estradiol and environmental estrogens significantly affect mammalian sperm function, Human. Reprod. 2003, 18, 100-107.

[13]         L. E. Bennetts, G. N. De Iuliis, B. Nixon, M. Kime, K. Zelski, C. M. McVicar, S. E. Lewis, R. J. Aitken, Impact of estrogenic compounds on DNA integrity in human spermatozoa: Evidence for cross-linking and redox cycling activities, Mutat. Res. 2008, 641, 1-11.

[14]         L. R. Fraser, E. Beyret, S. R. Milligan, S. A. Adeoya-Osiguwa, Effects of estrogenic xenobiotics on human and mouse spermatozoa, Human. Reprod. 2006, 21, 1184-1193.

[15]         M. R. Fielden, S. M. Samy, K. C. Chou, T. R. Zacharewski, Effect of human dietary exposure levels of genistein during gestation and lactation on long-term reproductive development and sperm quality in mice, Food Chem. Toxicol. 2003, 41, 447-454.

[16]         A. B. Wisniewski, S. L. Klein, Y. Lakshmanan, J. P. Gearhart, Exposure to Genistein During Gestation and Lactation Demasculinizes the Reproductive System in Rats, J. Urol. 2003, 169, 1582-1586.

[17]         V. Kyselova, J. Peknicova, M. Boubelik, D. Buckiova, Body and organ weight, sperm acrosomal status and reproduction after genistein and diethylstilbestrol treatment of CD1 mice in a multigenerational study, Theriogenology 2004, 61, 1307-1325.

[18]         K. Svechnikov, V. Supornsilchai, M.-L. Strand, A. Wahlgren, D. Seidlova-Wuttke, W. Wuttke, O. Söder, Influence of long-term dietary administration of procymidone, a fungicide with anti-androgenic effects, or the phytoestrogen genistein to rats on the pituitary–gonadal axis and Leydig cell steroidogenesis, J. Endocrinol. 2005, 187, 117-124.

[19]         E. Kilian, R. Delport, M. S. Bornman, C. d. Jager, Simultaneous exposure to low concentrations of dichlorodiphenyltrichloroethane, deltamethrin, nonylphenol and phytoestrogens has negative effects on the reproductive parameters in male Spraque-Dawley rats, Andrologia 2007, 39, 128-135.

[20]         M. Messina, Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence, Fertil. Steril. 2010, 93, 2095-2104.

[21]         M. Messina, O. Kucuk, J. W. Lampe, An Overview of the Health Effects of Isoflavones with an Emphasis on Prostate Cancer Risk and Prostate-Specific Antigen Levels, J. AOAC Int. 2006, 89, 1121-1134.

[22]         M. S. Kurzer, Hormonal Effects of Soy in Premenopausal Women and Men, J. Nutr. 2002, 132, 570S-573S.

[23]         M. A. van Erp-Baart, H. A. Brants, M. Kiely, A. Mulligan, A. Turrini, C. Sermoneta, A. Kilkkinen, L. M. Valsta, Isoflavone intake in four different European countries: the VENUS approach, Br J Nutr 2003, 89 Suppl 1, S25-30.

[24]         I. C. Munro, M. Harwood, J. J. Hlywka, A. M. Stephen, J. Doull, W. G. Flamm, H. Adlercreutz, Soy Isoflavones: A Safety Review, Nutr. Rev. 2003, 61, 1-33.

[25]         A. A. Thorp, N. Sinn, J. D. Buckley, A. M. Coates, P. R. C. Howe, Soya isoflavone supplementation enhances spatial working memory in men, Br. J. Nutr. 2009, 102, 1348-1354.

[26]         T. Siepmann, J. Roofeh, F. W. Kiefer, D. G. Edelson, Hypogonadism and erectile dysfunction associated with soy product consumption, Nutrition 2011, 27, 859-862.

[27]         G. Song, L. Kochman, E. Andolina, R. C. Herko, K. J. Brewer, V. Lewis, O-115: Beneficial effects of dietary intake of plant phytoestrogens on semen parameters and sperm DNA integrity in infertile men, Fertil. Steril. 2006, 86, S49.

[28]         W. Y. Wong, H. M. W. M. Merkus, C. M. G. Thomas, R. Menkveld, G. A. Zielhuis, R. P. M. Steegers-Theunissen, Effects of folic acid and zinc sulfate on male factor subfertility: a double-blind, randomized, placebo-controlled trial, Fertil. Steril. 2002, 77, 491-498.

[29]         M. R. Safarinejad, S. Y. Hosseini, F. Dadkhah, M. A. Asgari, Relationship of omega-3 and omega-6 fatty acids with semen characteristics, and anti-oxidant status of seminal plasma: A comparison between fertile and infertile men, Clin. Nutr. 2010, 29, 100-105.

[30]         D. W. Singleton, S. A. Khan, Xenoestrogen exposure and mechanisms of endocrine disruption, Front Biosci 2003, 8, s110-118.

[31]         F. Eertmans, W. Dhooge, S. Stuyvaert, F. Comhaire, Endocrine disruptors: effects on male fertility and screening tools for their assessment, Toxicol. In Vitro 2003, 17, 515-524.

[32]         R. M. Sharpe, N. E. Skakkebaek, Are oestrogens involved in falling sperm counts and disorders of the male reproductive tract?, The Lancet 1993, 341, 1392-1396.

[33]         A. C. Vidaeff, L. E. Sever, In utero exposure to environmental estrogens and male reproductive health: a systematic review of biological and epidemiologic evidence, Reprod. Toxicol. 2005, 20, 5-20.

[34]         J. M. Hamilton-Reeves, G. Vazquez, S. J. Duval, W. R. Phipps, M. S. Kurzer, M. J. Messina, Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis, Fertil. Steril. 2010, 94, 997-1007.

Especially the outcome of the OPUS study, a multicenter, randomized, double-blind, placebocontrolled 24-month trial with supplementation of 80 or 120 mg aglycone equivalent soy hypocotyl isoflavones plus calcium and vitamin D on the health on 403 postmenopausal women is supporting that fact. Maskarinec at al did conclude in 2009 that isoflavone supplements containing of SoyLife did not modify breast density in postmenopausal women and that breast density decrease was normal throughout the course of the OPUS study. These results show that a long-term intake of soy germ isoflavones in high concentrations do not have a negative influence on breast health. In addition Steinberg et al did conclude in 2010 that daily supplementation of daidzein rich soy products can be regarded as safe in healthy menopausal women. In general research of the last year did show that consumption of soy products and/or supplements can be considered as safe. Also in the clinical trials where equol was supplemented no significant adverse effects were observed. Finally no significant side/adverse effects were reported by supplementation of daidzein rich products to male persons.

By Notox, The Netherlands, 2000 and 2001.
Maskarinec et al J. Nutr. 139 (2009), 981-986.
Francene M Steinberg, Am J Clin Nutr. 2011 Feb;93(2):356-67.

What is this?

SoyLife is a unique soy isoflavone ingredient manufactured exclusively from soy germ. Soy germ (rather than either whole bean or the fermented bi-products of ex- traction) contains the highest natural level of isoflavones combined with more than 40 other phytonutrients. SoyLife provides you with a powerful and rich ingredient for inclusion in either dietary supplement, functional food or cosmetic applications. SoyLife has been the leading isoflavone product for more than 14 years, contributing to the scientific understanding and acceptance of the health benefits of soy isoflavones and the market success of more than 800 products launched world-wide.

Advantages

• It is either a 100% natural source or a gently extracted ingredient for higher concentrations (no harsh solvents used).
• Extensive safety and efficacy studies have been completed at a daily dose of 120 mg (aglycones) over a 2 year period.
• Daidzein is a precursor to equol, a potent isoflavone which is proven to be a key to the health benefits of soy germ isoflavones.
• More than 35 proprietary studies provide support for health claims.
• The isoflavones are in a ‘matrix’ with other natural phytonutrients that work synergistically together for health benefits.
• Higher percentage of both daidzein and glycitein than other soy isoflavone ingredients.
• Readily bio-available in the natural glycoside form.
• Strong IP and patented protected ingredient.

Health Benefits

SoyLife has been extensively researched over the past 14 years and most of the earlier consumer products were developed for the relief of menopausal symptoms as well as reduction of LDL and improvement in HDL in post-menopausal women. More recent studies have been focussed on possible benefits in osteoporosis, incontinence and cognitive function when combined with other ingredients.

New study results provide exciting new evidence-based claims position

• Soylife, Calcium and Vit D in the prevention of osteoporosis – OPUS study 2004–2007

 SoyLife is superior to other isoflavone sources

Soy isoflavones are offered in various forms, such as soy germ concentrates and soy molasses extracts. The benefits of SoyLife over other isoflavone extracts all relate to the basic composition of the product:

• SoyLife contains a rich complex of bioactive soy nutrients, surrounding a guaranteed high isoflavone concentration. This is the SoyLife Soy Matrix®.
• SoyLife is high in daidz(e)in, the precursor of equol – an especially potent isoflavone.
• SoyLife ingredients are not manufactured from the by-product molasses, but from the all natural, nutritional soy germ.
• In SoyLife production, no harsh solvents are used.
• The safety and efficacy of SoyLife’s Soy Matrix is supported with numerous proprietary scientific studies.

Applications of SoyLife

In SoyLife research, a daily isoflavone intake of 40-80 mg per day (as aglycones) has shown beneficial effects on health. Manufacturers should check with local authorities regarding allowable dosages of isoflavones. This amount of isoflavones is contained in only 0.1-2 grams of SoyLife, depending on the type of SoyLife you prefer to use.

SoyLife is non-GMO, kosher and halal is available. Due to a complete profile of soy nutrients in SoyLife plus the small dosage requirements, SoyLife opens up an array of new opportunities for applications such as: one-per-day capsules and tablets, foods (cereals, bakery products etc.), cosmetics and more.

Go-Less bladder control product clinically shown to help:

• Reduce urinary urgency
• Regain bladder control
• Support prostate health

OsteoLife bone health product clinically shown to help:

• Promote new bone formation
• Helps improve bone health
• Prevention of bone loss

After the conclusion of the study two key findings were observed:

1. 120 mg of SoyLife aglycone isoflavones in combination with Calcium and Vitamin D had a significant favourable effect on whole body mineral density (BMD), and
2. this dosage had no undesirable effects after 2 years.

SoyLife EXTRA is a soy germ concentrate standardized to 10% isoflavones. Specially selected high-quality soy germs are the starting material for SoyLife EXTRA production. This is different from many isoflavone extracts, which are concentrated from soy molasses, or other materials that result from extensive fractionations.

Because SoyLife EXTRA has been produced from soy germ, the isoflavones in SoyLife EXTRA are present in their natural matrix of soy micronutrients, such as 8% unsaturated fatty acids, 14% dietary fibers, 15% prebiotic oligosaccharides, 30% highly nutritious protein and 10% saponins. More and more, scientists draw the conclusion that this natural Soy Matrix® may enhance the efficacy of the isoflavones.

Isoflavone profile

The isoflavone profile of SoyLife EXTRA has a typical soy germ ratio of genistein : daidzein : glycitein, which is 15 : 50 : 35. Isoflavones are related to health benefits such as relief of menopausal symptoms, PMS, bone health, and heart health. The efficacy of SoyLife extracts has been confirmed in a number of clinical studies. The fact that SoyLife EXTRA is relatively rich in the isoflavone daidzein is interesting, as scientists increasingly attach value to the efficacy of its metabolite equol.

Application and dosage

SoyLife EXTRA offers you the convenience of one-per-day capsules and tablets. The ingredient is also ideal for soft-gel capsules, as it is has a lighter color and a smaller granulation than many other isoflavone ingredients. In a wide variety of food applications, SoyLife EXTRA behaves like soy flour. It can add to the structure of food products, without altering the taste profile. Depending on the health message on your label, the recommended inclusion of SoyLife EXTRA varies between 300 and 600 mg per day.

Quality

SoyLife EXTRA is a tan / white powder. Its taste is slightly bitter, due to its richness in isoflavones. SoyLife EXTRA is kosher, halal and non-GMO, and packaged in 10 kg cardboard drums with polyethylene inliner.

Females perform better in certain memory-related tasks than males. Sex differences in cognitive performance may be attributable to differences in circulating oestrogen acting on oestrogen beta receptors (ERbeta) which are prevalent in brain regions such as the hippocampus, frontal lobe and cortex that mediate cognitive functions. Since soya isoflavones are known to activate ERbeta, chronic isoflavone supplementation in males may improve cognitive performance in memory-related tasks. A 12-week double-blind, placebo-controlled cross-over trial was conducted in thirty-four healthy men to investigate the effect of isoflavone supplementation on cognitive function. Volunteers were randomised to take four capsules/d containing soya isoflavones (116 mg isoflavone equivalents/d: 68 mg daidzein, 12 mg genistein, 36 mg glycitin) or placebo for 6 weeks, and the alternate treatment during the following 6 weeks. Assessments of memory (verbal episodic, auditory and working), executive function (planning, attention, mental flexibility) and visual-spatial processing were performed at baseline and after each treatment period. Isoflavone supplementation significantly improved spatial working memory (P = 0.01), a test in which females consistently perform better than males. Compared with placebo supplementation, there were 18 % fewer attempts (P = 0.01), 23 % fewer errors (P = 0.02) and 17 % less time (P = 0.03) required to correctly identify the requisite information. Isoflavones did not affect auditory and episodic memory (Paired Associate Learning, Rey’s Auditory Verbal Learning Task, Backward Digit Span and Letter-Number Sequencing), executive function (Trail Making and Initial Letter Fluency Task) or visual-spatial processing (Mental Rotation Task). Isoflavone supplementation in healthy males may enhance cognitive processes which appear dependent on oestrogen activation.

Genetic toxicology focuses on the process of mutagenesis, that includes the induction of DNA damage and all kinds of genetic changes, ranging from alterations in one or a few DNA base pairs (gene mutations) to gross changes in chromosome structure (chromosome aberrations) or chromosome number. Mutagens are of concern, because genetic damage may contribute to diseases like cancer. Mutagenicity testing should detect the diverse kinds of mutations that are relevant for human health. Therefore a set of tests are needed.

Subacute 28-day oral toxicity with SoyLife COMPLEX by daily gavage in the rat, 2000. 14-day oral range finding with SoyLife EXTRA by daily gavage in the rat. 2001. For both SoyLife COMPLEX and SoyLife EXTRA the maximum dosage administered to the rats was 1000 mg, because the rats were practically not able to eat more than this quantity per day. From the results presented in this report a No Observed Adverse Effect Level (NOAEL) for SoyLife COMPLEX of 1000 mg / kg / day was concluded. For the interpretation of this result, it is important to note that 1000 mg SoyLife / kg / day for rats equals 70 g SoyLife / day for humans. In both studies, no adverse effects were detected with respect to growth, behavior, food & water intake, and organ weights and structure.

SoyLife EXTRA was tested in the Salmonella typhimurium reverse mutation assay with four histidine-requiring strains of Salmonella typhimurium (TA1535, TA1537, TA100 and TA98) and in the Escherichia coli reverse mutation assay with a tryptophan-requiring strain of Escherichia coli WP2uvrA in two independent experiments. 2000. Part of these tests are better known as “Ames- test”, and is a bacterial test to detect gene mutations (changes in DNA base pairs). Based on the results of this study, it is concluded that SoyLife EXTRA is not mutagenic in the Salmonella typhimurium reverse mutation assay and the Escherichia coli reverse mutation assay at a concentration of 5,000μg SoyLife EXTRA per plate. These tests have been carried out in the absence and presence of metabolic activation (the rat liver homogenate S9- mix).

Effect of SoyLife EXTRA on the induction of chromosome aberrations in cultured peripheral human lymphocytes in the presence and absence of a metabolic activation system, 2000.

Gros changes in chromosome structures can be detected by microscopy in human lymphocytes incubated with the compound of interest. SoyLife EXTRA did not produce a biologically relevant or statistically significant increase in the number of cells with chromosome aberrations in the absence and in the presence of S9-mix (metabolic activation) at a dose of 333μg SoyLife EXTRA / ml. From this test it is concluded that SoyLife EXTRA is not clastogenic (the correct term “inducing chromosome aberrations”) in human lymphocytes.

Micronucleus test with SoyLife EXTRA in mice to evaluate its genotoxic effect on erythrocytes in bone. 2000.

This in vivo cytogenetic test involves treating intact animals with SoyLife EXTRA, and the preparation of cell samples for the detection of chromosome abarrations. This test offers the advantage that the mammalian metabolism and distribution of the compound are part of the essay. SoyLife EXTRA was tested in rats to evaluate its genotoxic effect on erythrocytes in bone marrow. Male and female rats were appointed to 2000, 1000 or 500 mg SoyLife EXTRA / kg body weight, or a negative or positive control. The SoyLife EXTRA groups showed no decrease in the ratio of polychromatic to normochromatic erythrocytes compared to the vehicle controls. This reflects the absence of toxic effects of this compound on the erythropoiesis. Based on the results in this study, it is concluded that SoyLife EXTRA is not mutagenic in the micronucleus test.

High mammographic densities confer a higher risk to develop breast cancer. Several studies have indicated that dietary and hormonal factors may modify breast density. Discussion exists sometimes if soy isoflavones may protect against breast cancer as a result of their antiestrogenic activity or could be hypothesized to increase risk as a result of their estrogen-like properties. Also, breast density is inversely associated with age and BMI (1). The Osteoporosis Prevention Using Soy (OPUS) study examined the relation between different doses of an isoflavone supplement and mammographic density in a 2-year long clinical trial designed to document the safety, efficacy and optimal dosage of soy isoflavones to prevent bone loss after menopause.

Study design

The OPUS study was a 2-year, follow-up, multicenter, randomized, double-blind, placebocontrolled, and intent-to-treat clinical trial. A group of 406 postmenopausal women in their early years of menopause were enrolled at 3 collaborating sites. Of the participants, 135 women received 80 mg/d of isoflavone therapy, 134 received 120 mg/d of isoflavone therapy, and the remaining 135 received a placebo. To account for potential differences and changes in isoflavone intakes across groups, each woman completed a Food Frequency Questionnaire (FFQ) before and after 12 and 24 months of treatment.

Mammograms were retrieved for participants performed at baseline, after 1 year, and after 2 years. All films were scanned and quantified for total breast area as well as the dense tissue in the breast to determine percent breast density. Statistical analysis was performed to determine the effects of isoflavones on breast density.

Results

The mammographic density analysis included 358 women, 88% of the OPUS study participants, 303 of whom had a complete set of 3 mammograms. At baseline, the groups were similar in age, BMI, and percent density. There were small variations in density per study site. Measures of mammographic density, i.e. the dense area and percent density, decreased significantly over time by approximately 3%, which reflects the normal decline in fibroglandular tissue in the aging breast. There were no statistically significant differences in percent annual decrease in densities between the treatment groups (placebo = 1.4% ± 0.3; 80mg = 1.6% ± 0.3; 120mg = 1.3% ± 0.3; P = 0.85).

Conclusion

The present OPUS study was well designed to examine possible effects of isoflavones: 2-year duration, large sample size (n = 358); low loss to follow-up (10%); and 2 different dosages of isoflavones to study the dose-response. Intake of an isoflavone supplement did not influence mammographic density. Stratification by age and BMI also did not indicate an effect of the treatment for any subgroup of women.

In this trial, isoflavone supplements did not modify breast density in postmenopausal women: breast density decrease was normal throughout the course of the OPUS study. These results show that a longterm intake of soy germ isoflavones in high concentrations do not have a negative influence on breast health.

Soy isoflavones have been given considerable attention in regard to breast cancer, both for prevention and for increasing risk.

Soy isoflavone antioxidant effects may help prevent breast cancer re-occurrence, but isoflavone estrogen-like actions may increase breast cancer risk. These isoflavone actions can be reflected by effects on two copper enzymes activities, superoxide dismutase 1 (SOD 1), which has antioxidant function relevant to breast cancer prevention, and ceruloplasmin, which has its synthesis up-regulated by estrogen, and for which high values are associated with high breast cancer risk. A soy isoflavone-rich concentrate supplement was examined for effects on these two copper enzyme activities in post-menopausal breast cancer survivors.

Study design

Seven postmenopausal breast cancer survivors (aged 50 – 65 years), who had completed chemotherapy and / or surgery at least 6 months earlier were recruited. Each subject was given soy isoflavone concentrate (SoyLife COMPLEX) and placebo (ground matzo), each for 24 days in a crossover design that included a 2-week washout period. The products were given in capsules at a daily serving of 3 capsules taken twice daily. The daily serving contained 138 mg isoflavones (81 mg daidz(e)in, 42 mg glycit(e)in and 15 mg genist(e)in.

The subjects were blinded as to the order of the treatments (soy or placebo first), which was determined randomly.

Blood and urine samples were analyzed for erythrocyte Cu-Zn SOD activity, for ceruloplasmin (as activity and as immuno-reactive protein) and urinary 8-hydroxy-2′-deoxyguanosine, a DNA oxidation product with relevance to breast cancer.

Results and conclusion

The results showed that supplementation with soy, but not with placebo, produced a statistically significant increase in erythrocyte SOD 1 activities. The increase in SOD 1 activities was not accompanied by a decrease in urinary 8- deoxyhydroxyguanosine. Ceruloplasmin activities and protein were unchanged by both treatments. The increase in SOD-activity could not be related to copper-intake.

In summary, SoyLife COMPLEX showed an antioxidant effect and increased SOD 1 activity considered relevant to reduced breast cancer risk, but not a ceruloplasmin increase associated with estrogenic activity and breast cancer risk. In this pilot study the soy isoflavone concentrate seemed safe and possibly protective in regard to breast cancer risk.

In most soy foods, genistein and daidzein account for about 80 – 90% of total isoflavones. In soy germ, the major isoflavones present are daidzein (45-60%) and glycitein (35-45%). In studies, the estrogenic activities of genistein and daidzein were reported to be about 100,000 to 500,000 times lower than that of diethylstilbestrol (DES). In this study, the estrogenic activity of glycitein was assessed, using SoyLife, a soy germ concentrate.

Study design

Two different tests were applied to test the estrogenic activity of glycitein. In the first test, purified isoflavones were tested in an in vitro estrogen receptor-binding assay. The second test involves a uterine enlargement test with B6D2F1 mice. This is a standard in vivo method to evaluate estrogenic activity. Because it is performed in animals, the effects of absorption, metabolism, serum binding and pharmacokinetics are taken into account. Eighty mice were randomly assigned to a 4-day treatment involving a placebo, to 0.12 μg DES per day, or to 12 mg per day of either genistein or glycitein. Glycitein was purified from SoyLife. The relative estrogenic potencies were estimated on the basis of the doses required to produce the same increase of uterine weights.

Results

The study demonstrated that the estrogenic potency of glycitein (as measured in the mice uterine enlargement assay) was in the same order, although somewhat higher than that of genistein. But, as hypothesized, the estrogenic potency of both isoflavones was much lower than that of DES or 17β-estradiol.

It is generally believed that non-steroidal estrogens such as isoflavones exert an estrogenic effect by binding to the same estrogen receptors as steroidal estrogens such as 17β-estradiol. Our study confirms that glycitein has the ability to bind to estrogen receptors.

However, among the three isoflavones, genistein had the greatest estrogen receptor binding affinity (as demonstrated in the in vitro ER-binding essay.

In conclusion

This study demonstrates that glycitein is a slightly stronger estrogen in vivo in mice compared to genistein, although the estrogenic activity of both compounds is much weaker than that of DES or 17β-estradiol. Contradictory, genistein was shown to have higher ER-binding affinity than glycitein in vitro. The somewhat higher in vivo estrogenic activity of glycitein compared to genistein may be a result of a higher bioavailability of glycitein. Further, the authors suggest that glycitein might be metabolized to other compounds, which have a greater estrogenic potency than that of glycitein. These metabolites were however not measured in this study.