Prostate Cancer, Nutrition, and Dietary Supplements (PDQ®)–Health Professional Version
Soy
Overview
This section contains the following key information:
- Soy foods (e.g., soy milk, miso, tofu, and soy flour) contain phytochemicals that may have health benefits and, among these, soy isoflavones have been the focus of most of the research.
- Soy isoflavones are phytoestrogens. The major isoflavones in soybeans are genistein(the most abundant), daidzein, and glycitein.
- Genistein affects components of multiple growth and proliferation -related pathways in prostate cancer cells, including the COX-2 /prostaglandin, epidermal growth factor(EGF), and insulin-like growth factor (IGF) pathways.
- Some preclinical studies have indicated that the combined effect of multiple isoflavones may be greater than that of a single isoflavone.
- Some animal studies have demonstrated prostate cancer prevention effects with soy and genistein; however, other animal studies have yielded conflicting results regarding beneficial effects of genistein on prostate cancer metastasis.
- Epidemiologic studies have generally found high consumption of nonfermented soy foods to be associated with a decreased risk of prostate cancer.
- Early-phase clinical trials with isoflavones, soy, and soy products for the prevention and treatment of prostate cancer have been limited to relatively short durations of intervention and sample sizes with low statistical power. These studies targeted heterogeneous prostate cancer patient populations (in high-risk, early- and later-stagedisease) and varying doses of isoflavones, soy, and soy products, and have not demonstrated evidence of reducing prostate cancer progression.
- Other trials evaluating the role of isoflavones, soy, or soy products in the management of androgen deprivation therapy (ADT) side effects have found no improvement with isoflavone treatment compared with placebo.
- Soy products are generally well tolerated in patients with prostate cancer. In clinical trials, the most commonly reported side effects were mild gastrointestinal symptoms.
General Information & History
Although records of soy use in China date back to the 11th century BC, it was not until the 18th century that the soy plant reached Europe and the United States. The soybean is an incredibly versatile plant. It can be processed into a variety of products including soy milk, miso, tofu, soy flour, and soy oil.[1]
Soy foods contain a number of phytochemicals that may have health benefits, but isoflavones have garnered the most attention. Among the isoflavones found in soybeans, genistein is the most abundant and may have the most biological activity.[2] Other isoflavones found in soy include daidzein and glycitein.[3] Many of these isoflavones are also found in other legumes and plants, such as red clover.
Isoflavones are quickly taken up by the gut and can be detected in plasma as soon as 30 minutes after the consumption of soy products. Studies suggest that maximum levels of isoflavone plasma concentration may be achieved by 6 hours after soy product consumption.[4] Isoflavones are phytoestrogens that bind to estrogen receptors. Prostate tissue is known to express estrogen receptor beta and it has been shown that the isoflavone genistein has greater affinity for estrogen receptor beta than for estrogen receptor alpha.[5]
A link between isoflavones and prostate cancer was first observed in epidemiological studies that demonstrated a lower risk of prostate cancer in populations consuming considerable amounts of dietary soy.[6,7] Subsequent studies evaluating the role of soy in experimental models further showed anticancer properties of soy, specifically relevant to prostate carcinogenesis. These early studies have led to a few clinical trials in humans using soy food products or supplements that targeted men with varying stages of prostate cancer. Although these studies showed modulation of intermediate endpoints or surrogate biomarkers of prostate cancer progression, the results indicating beneficial effects from soy or soy products have been mixed.
Preclinical/Animal Studies
In vitro studies
Individual isoflavones
A number of laboratory studies have examined ways in which soy components affect prostate cancer cells. In one study, human prostate cancer cells and normal prostate epithelial cells were treated with either an ethanol vehicle (carrier) or isoflavones. Treatment with genistein decreased COX-2 mRNA and protein levels in cancer cells and normal epithelial cells more than did treatment with the vehicle. In addition, cells treated with genistein exhibited reduced secretion of prostaglandin E2 (PGE2) and reduced mRNA levels of the prostaglandin receptors EP4 and FP, suggesting that genistein may exert chemopreventive effects by inhibiting the synthesis of prostaglandins, which promote inflammation.[8] In another study, human prostate cancer cells were treated with genistein or daidzein. The isoflavones were shown to down regulate growth factors involved in angiogenesis (e.g., EGF and IGF-1) and the interleukin -8 gene, which is associated with cancer progression. These findings suggest that genistein and daidzein may have chemopreventive properties.[9] Both genistein and daidzein have been shown to reduce the proliferation of LNCaP and PC-3 prostate cancer cells in vitro . However, during the 72 hours of incubation, only genistein provoked effects on the dynamic phenotype and decreased invasiveness in PC-3 cells. These results imply that invasive activity is at least partially dependent on membrane fluidity and that genistein may exert its antimetastatic effects by changing the mechanical properties of prostate cancer cells. No such effects were observed for daidzein at the same dose.[10]
Combinations of isoflavones
Some experiments have compared the effects of individual isoflavones with isoflavone combinations on prostate cancer cells. In one study, human prostate cancer cells were treated with a soy extract (containing genistin, daidzin, and glycitin), genistein, or daidzein. The soy extract induced cell cycle arrest and apoptosis in prostate cancer cells to a greater degree than did treatment with the individual isoflavones. Genistein and daidzein activated apoptosis in noncancerous benign prostatic hyperplasia (BPH) cells, but the soy extract had no effect on those cells. These findings suggested that products containing a combination of active compounds (e.g., whole foods) may be more effective in preventing cancer than individual compounds.[11] Similarly, in another study, prostate cancer cells were treated with genistein, biochanin A, quercetin, doublets of those compounds (e.g., genistein + quercetin), or with all three compounds. All of the treatments resulted in decreased cell proliferation, but the greatest reductions occurred using the combination of genistein, biochanin A, and quercetin. The triple combination treatment induced more apoptosis in prostate cancer cells than did individual or doublet compound treatments. These results indicate that combining phytoestrogens may increase the effectiveness of the individual compounds.[12]
At least one study has examined the combined effect of soy isoflavones and curcumin. Human prostate cancer cells were treated with isoflavones, curcumin, or a combination of the two. Curcumin and isoflavones in combination were more effective in lowering PSA levels and expression of the androgen receptor than were curcumin or the isoflavones individually.[13]
Animal studies
Animal models of prostate cancer have been used in studies investigating the effects of soy and isoflavones on the disease. Wild-type and transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were fed control diets or diets containing genistein (250 mg genistein/kg chow). The TRAMP mice fed with genistein exhibited reduced cell proliferation in the prostate compared with TRAMP mice fed a control diet. The genistein-supplemented diet also reduced levels of ERK-1 and ERK-2 (proteins important in stimulating cell proliferation) as well as the growth factor receptors EGFR and IGF-1R in TRAMP mice, suggesting that down regulation of these proteins may be one mechanism by which genistein exerts chemopreventive effects.[14] In one study, following the appearance of spontaneous prostatic intraepithelial neoplasia lesions, TRAMP mice were fed control diets or diets supplemented with genistein (250 or 1,000 mg genistein/kg chow). Mice fed low-dose genistein exhibited more cancer cell metastasis and greater osteopontin expression than mice fed the control or the high-dose genistein diet. These results indicate that timing and dose of genistein treatment may affect prostate cancer outcomes and that genistein may exert biphasic control over prostate cancer.[15] In a study reported in 2008, athymic mice were implanted with human prostate cancer cells and fed a control or genistein-supplemented diet (100 or 250 mg genistein/kg chow). Mice that were fed genistein exhibited less cancer cell metastasis, but no change in primary tumor volume, than did mice fed a control diet. Furthermore, other data suggested that genistein inhibits metastasis by impairing cancer cell detachment.[16] In contrast, in a study reported in 2011, there were more metastases in secondary organs in genistein-treated mice than in vehicle-treated mice. In this latter study, mice were implanted with human prostate cancer xenografts and treated daily with genistein dissolved in peanut oil (80 mg genistein/kg body weight/day or 400 mg genistein/kg body weight/d) or peanut oil vehicle by gavage. In addition, there was a reduction in tumor cell apoptosis in the genistein-treated mice compared with the vehicle-treated mice. These findings suggest that genistein may stimulate metastasis in an animal model of advanced prostate cancer.[17]
Radiation therapy is commonly used in prostate cancer, but, despite this treatment, disease recurrence is common. Therefore, combining radiation with additional therapies may provide longer-lasting results. In one study, human prostate cancer cells were treated with soy isoflavones and/or radiation. Cells that were treated with both isoflavones and radiation exhibited greater decreases in cell survival and greater expression of proapoptotic molecules than cells treated with isoflavones or radiation only. Nude mice were implanted with prostate cancer cells and treated by gavage with genistein (21.5 mg/kg body weight/d), mixed isoflavones (50 mg/kg body weight/d; contained 43% genistein, 21% daidzein, and 2% glycitein) and/or radiation. Mixed isoflavones were more effective than genistein in inhibiting prostate tumor growth, and combining isoflavones with radiation resulted in the largest inhibition of tumor growth. In addition, mice given soy isoflavones in combination with radiation did not exhibit lymph node metastasis, which was seen previously in other experiments combining genistein with radiation. These preclinical findings suggest that mixed isoflavones may increase the efficacy of radiation therapy for prostate cancer.[18]
In the treatment of prostate cancer, bone health is a common concern in the setting of hormone deprivation therapy, which is associated with bone loss. Because of increased beta versus alpha estrogen receptor binding, soy-derived compounds are thought to be protective of bone. Animal studies have shown that genistein and daidzein can prevent or reduce bone loss in a manner similar to synthetic estrogen. Both isoflavones may modulate bone remodeling by targeting and regulating gene expression and may inhibit calcium urine excretion, which also helps to maintain bone density.[19,20]
Human Studies
Human studies evaluating isoflavones and soy for the prevention and treatment of prostate cancer have included epidemiological studies and early-phase trials. Several phase I-II randomized clinical studies have examined isoflavones and soy product for bioavailability, safety, and effectiveness in prostate cancer prevention or treatment.[21-23] These studies have included a wide range of subject populations, including high-risk men; prostate cancer patient populations (localized and later-stage disease); varying doses of isoflavones, soy, and soy products; and were limited to relatively short durations of observation or intervention and sample sizes with low statistical power.
Epidemiologic studies
In 2018, a meta-analysis of studies that investigated soy food consumption and risk of prostate cancer was reported. The results of this meta-analysis suggested that high consumption of nonfermented soy foods (e.g., tofu and soybean milk) was significantly associated with a decrease in the risk of prostate cancer. Fermented soy food intake, total isoflavone intake, and circulating isoflavones were not associated with a reduced risk of prostate cancer.[24] However, these data from population studies must be interpreted with caution as the studies relied on self-reported data obtained using varying forms of dietary data collection instruments with recall bias, in addition to numerous forms of individual or multiple isoflavones, soy supplements, and soy foods. Additionally, these studies failed to account for other confounding genetic or behavioral variables that may affect the risk of prostate cancer.
Prevention studies
Too few randomized placebo-controlled trials have been completed to evaluate the effect of isoflavones or soy in preventing prostate cancer progression (refer to Table 3). The studies targeted men with negative prostate biopsies and elevated serum prostate-specific antigen (PSA) (2.5–10 mcg/mL at baseline). The duration of intervention was between 6 months [13] and 1 year [25,26], with varying formulations of isoflavones derived from soy [13,25] and red clover.[26] In a single trial that showed no significant changes in serum PSA after intervention with isoflavones, a reduction in prostate cancer progression at 1 year in a subgroup of men older than 65 years was demonstrated. Other than mild to moderate adverse events, no treatment-related toxicities were observed in all three trials.
Treatment of prostate cancer
Clinical trials evaluating isoflavones, soy supplements, and soy products (refer to Table 4and Table 5) for treating localized prostate cancer before radical prostatectomy have used window-of-opportunity trial designs (from biopsy to prostatectomy). These trials have primarily focused on evaluating serum and tissue biomarkers implicated in prostate cancer progression, bioavailability in plasma and prostate tissue, and toxicity at various doses. The trials are small in size and of short duration. They are useful for informing the design of well-powered larger clinical trials in the future, but they provide inadequate data to inform clinical practice.
Isoflavones
Soy protein or whole soy products
Isoflavones and soy products for biochemical recurrence after treatment
Other studies have examined the role of isoflavones and soy products in prostate cancer patients with biochemical recurrence after treatment. However, these early-phase studies have not demonstrated any significant changes in serum PSA or PSA-doubling time, [38-41] with one study suggesting modulation of systemic soluble and cellular biomarkers consistent with limiting inflammation and suppression of myeloid-derived suppressor cells [41] (refer to Table 6).
Management of androgen deprivation therapy side-effects
ADT is commonly used for locally advanced and metastatic prostate cancer. However, this treatment is associated with a number of adverse side effects including sexual dysfunction, decreased quality of life, changes in cognition, and metabolic syndrome. Three studies have examined men undergoing ADT who were randomly assigned to receive a placebo or an isoflavone supplement (soy protein powder mixed with beverages; isoflavones, 160 mg/d) for 12 weeks. Two studies assessed ADT side effects. Neither study found an improvement in side effects following isoflavone treatment, compared with placebo.[42,43]
The third randomized placebo-controlled trial assessed changes in PSA level and biomarkers of energy metabolism (e.g., blood glucose level) and inflammation (e.g., blood interleukin-6 level). In this study of men undergoing ADT, participants were randomly assigned to receive high-dose isoflavone supplements (providing 160 mg/d total isoflavones, and containing 64 mg genistein, 63 mg daidzein, and 34 mg glycitein) or a placebo for 12 weeks. The results showed no difference between the two groups in PSA levels or in levels of metabolic and inflammatory parameters (e.g., glucose, interleukin-6).[36]
Current Clinical Trials
Use our advanced clinical trial search to find NCI-supported cancer clinical trials that are now enrolling patients. The search can be narrowed by location of the trial, type of treatment, name of the drug, and other criteria. General information about clinical trials is also available.
Adverse Effects
References
- Barnes S: The biochemistry, chemistry and physiology of the isoflavones in soybeans and their food products. Lymphat Res Biol 8 (1): 89-98, 2010. [PUBMED Abstract]
- Omoni AO, Aluko RE: Soybean foods and their benefits: potential mechanisms of action. Nutr Rev 63 (8): 272-83, 2005. [PUBMED Abstract]
- Jian L: Soy, isoflavones, and prostate cancer. Mol Nutr Food Res 53 (2): 217-26, 2009. [PUBMED Abstract]
- Andres S, Abraham K, Appel KE, et al.: Risks and benefits of dietary isoflavones for cancer. Crit Rev Toxicol 41 (6): 463-506, 2011. [PUBMED Abstract]
- Kuiper GG, Carlsson B, Grandien K, et al.: Comparison of the ligand binding specificity and transcript tissue distribution of estrogen receptors alpha and beta. Endocrinology 138 (3): 863-70, 1997. [PUBMED Abstract]
- Messina M, Kucuk O, Lampe JW: An overview of the health effects of isoflavones with an emphasis on prostate cancer risk and prostate-specific antigen levels. J AOAC Int 89 (4): 1121-34, 2006 Jul-Aug. [PUBMED Abstract]
- Messina MJ: Emerging evidence on the role of soy in reducing prostate cancer risk. Nutr Rev 61 (4): 117-31, 2003. [PUBMED Abstract]
- Swami S, Krishnan AV, Moreno J, et al.: Inhibition of prostaglandin synthesis and actions by genistein in human prostate cancer cells and by soy isoflavones in prostate cancer patients. Int J Cancer 124 (9): 2050-9, 2009. [PUBMED Abstract]
- Rabiau N, Kossaï M, Braud M, et al.: Genistein and daidzein act on a panel of genes implicated in cell cycle and angiogenesis by polymerase chain reaction arrays in human prostate cancer cell lines. Cancer Epidemiol 34 (2): 200-6, 2010. [PUBMED Abstract]
- Ajdžanović V, Mojić M, Maksimović-Ivanić D, et al.: Membrane fluidity, invasiveness and dynamic phenotype of metastatic prostate cancer cells after treatment with soy isoflavones. J Membr Biol 246 (4): 307-14, 2013. [PUBMED Abstract]
- Hsu A, Bray TM, Helferich WG, et al.: Differential effects of whole soy extract and soy isoflavones on apoptosis in prostate cancer cells. Exp Biol Med (Maywood) 235 (1): 90-7, 2010. [PUBMED Abstract]
- Kumar R, Verma V, Jain A, et al.: Synergistic chemoprotective mechanisms of dietary phytoestrogens in a select combination against prostate cancer. J Nutr Biochem 22 (8): 723-31, 2011. [PUBMED Abstract]
- Ide H, Tokiwa S, Sakamaki K, et al.: Combined inhibitory effects of soy isoflavones and curcumin on the production of prostate-specific antigen. Prostate 70 (10): 1127-33, 2010. [PUBMED Abstract]
- Wang J, Eltoum IE, Lamartiniere CA: Genistein alters growth factor signaling in transgenic prostate model (TRAMP). Mol Cell Endocrinol 219 (1-2): 171-80, 2004. [PUBMED Abstract]
- El Touny LH, Banerjee PP: Identification of a biphasic role for genistein in the regulation of prostate cancer growth and metastasis. Cancer Res 69 (8): 3695-703, 2009. [PUBMED Abstract]
- Lakshman M, Xu L, Ananthanarayanan V, et al.: Dietary genistein inhibits metastasis of human prostate cancer in mice. Cancer Res 68 (6): 2024-32, 2008. [PUBMED Abstract]
- Nakamura H, Wang Y, Kurita T, et al.: Genistein increases epidermal growth factor receptor signaling and promotes tumor progression in advanced human prostate cancer. PLoS One 6 (5): e20034, 2011. [PUBMED Abstract]
- Raffoul JJ, Banerjee S, Che M, et al.: Soy isoflavones enhance radiotherapy in a metastatic prostate cancer model. Int J Cancer 120 (11): 2491-8, 2007. [PUBMED Abstract]
- Hasler CM, Finn SC: Soy: just a hill of beans? J Womens Health 7 (5): 519-23, 1998. [PUBMED Abstract]
- Tang X, Zhu X, Liu S, et al.: Isoflavones suppress cyclic adenosine 3',5'-monophosphate regulatory element-mediated transcription in osteoblastic cell line. J Nutr Biochem 22 (9): 865-73, 2011. [PUBMED Abstract]
- Hwang YW, Kim SY, Jee SH, et al.: Soy food consumption and risk of prostate cancer: a meta-analysis of observational studies. Nutr Cancer 61 (5): 598-606, 2009. [PUBMED Abstract]
- van Die MD, Bone KM, Williams SG, et al.: Soy and soy isoflavones in prostate cancer: a systematic review and meta-analysis of randomized controlled trials. BJU Int 113 (5b): E119-30, 2014. [PUBMED Abstract]
- Jackson MD, McFarlane-Anderson ND, Simon GA, et al.: Urinary phytoestrogens and risk of prostate cancer in Jamaican men. Cancer Causes Control 21 (12): 2249-57, 2010. [PUBMED Abstract]
- Applegate CC, Rowles JL, Ranard KM, et al.: Soy Consumption and the Risk of Prostate Cancer: An Updated Systematic Review and Meta-Analysis. Nutrients 10 (1): , 2018. [PUBMED Abstract]
- Miyanaga N, Akaza H, Hinotsu S, et al.: Prostate cancer chemoprevention study: an investigative randomized control study using purified isoflavones in men with rising prostate-specific antigen. Cancer Sci 103 (1): 125-30, 2012. [PUBMED Abstract]
- Engelhardt PF, Riedl CR: Effects of one-year treatment with isoflavone extract from red clover on prostate, liver function, sexual function, and quality of life in men with elevated PSA levels and negative prostate biopsy findings. Urology 71 (2): 185-90; discussion 190, 2008. [PUBMED Abstract]
- Lazarevic B, Boezelijn G, Diep LM, et al.: Efficacy and safety of short-term genistein intervention in patients with localized prostate cancer prior to radical prostatectomy: a randomized, placebo-controlled, double-blind Phase 2 clinical trial. Nutr Cancer 63 (6): 889-98, 2011. [PUBMED Abstract]
- Hamilton-Reeves JM, Banerjee S, Banerjee SK, et al.: Short-term soy isoflavone intervention in patients with localized prostate cancer: a randomized, double-blind, placebo-controlled trial. PLoS One 8 (7): e68331, 2013. [PUBMED Abstract]
- deVere White RW, Tsodikov A, Stapp EC, et al.: Effects of a high dose, aglycone-rich soy extract on prostate-specific antigen and serum isoflavone concentrations in men with localized prostate cancer. Nutr Cancer 62 (8): 1036-43, 2010. [PUBMED Abstract]
- Kumar NB, Krischer JP, Allen K, et al.: A Phase II randomized, placebo-controlled clinical trial of purified isoflavones in modulating steroid hormones in men diagnosed with localized prostate cancer. Nutr Cancer 59 (2): 163-8, 2007. [PUBMED Abstract]
- Kumar NB, Krischer JP, Allen K, et al.: Safety of purified isoflavones in men with clinically localized prostate cancer. Nutr Cancer 59 (2): 169-75, 2007. [PUBMED Abstract]
- Kumar NB, Kang L, Pow-Sang J, et al.: Results of a randomized phase I dose-finding trial of several doses of isoflavones in men with localized prostate cancer: administration prior to radical prostatectomy. J Soc Integr Oncol 8 (1): 3-13, 2010. [PUBMED Abstract]
- Jarrard D, Konety B, Huang W, et al.: Phase IIa, randomized placebo-controlled trial of single high dose cholecalciferol (vitamin D3) and daily Genistein (G-2535) versus double placebo in men with early stage prostate cancer undergoing prostatectomy. Am J Clin Exp Urol 4 (2): 17-27, 2016. [PUBMED Abstract]
- Kumar NB, Cantor A, Allen K, et al.: The specific role of isoflavones in reducing prostate cancer risk. Prostate 59 (2): 141-7, 2004. [PUBMED Abstract]
- Gardner CD, Oelrich B, Liu JP, et al.: Prostatic soy isoflavone concentrations exceed serum levels after dietary supplementation. Prostate 69 (7): 719-26, 2009. [PUBMED Abstract]
- Napora JK, Short RG, Muller DC, et al.: High-dose isoflavones do not improve metabolic and inflammatory parameters in androgen-deprived men with prostate cancer. J Androl 32 (1): 40-8, 2011 Jan-Feb. [PUBMED Abstract]
- Dalais FS, Meliala A, Wattanapenpaiboon N, et al.: Effects of a diet rich in phytoestrogens on prostate-specific antigen and sex hormones in men diagnosed with prostate cancer. Urology 64 (3): 510-5, 2004. [PUBMED Abstract]
- Kwan W, Duncan G, Van Patten C, et al.: A phase II trial of a soy beverage for subjects without clinical disease with rising prostate-specific antigen after radical radiation for prostate cancer. Nutr Cancer 62 (2): 198-207, 2010. [PUBMED Abstract]
- Pendleton JM, Tan WW, Anai S, et al.: Phase II trial of isoflavone in prostate-specific antigen recurrent prostate cancer after previous local therapy. BMC Cancer 8: 132, 2008. [PUBMED Abstract]
- Bosland MC, Kato I, Zeleniuch-Jacquotte A, et al.: Effect of soy protein isolate supplementation on biochemical recurrence of prostate cancer after radical prostatectomy: a randomized trial. JAMA 310 (2): 170-8, 2013. [PUBMED Abstract]
- Lesinski GB, Reville PK, Mace TA, et al.: Consumption of soy isoflavone enriched bread in men with prostate cancer is associated with reduced proinflammatory cytokines and immunosuppressive cells. Cancer Prev Res (Phila) 8 (11): 1036-44, 2015. [PUBMED Abstract]
- Sharma P, Wisniewski A, Braga-Basaria M, et al.: Lack of an effect of high dose isoflavones in men with prostate cancer undergoing androgen deprivation therapy. J Urol 182 (5): 2265-72, 2009. [PUBMED Abstract]
- Vitolins MZ, Griffin L, Tomlinson WV, et al.: Randomized trial to assess the impact of venlafaxine and soy protein on hot flashes and quality of life in men with prostate cancer. J Clin Oncol 31 (32): 4092-8, 2013. [PUBMED Abstract]
- Maskarinec G, Morimoto Y, Hebshi S, et al.: Serum prostate-specific antigen but not testosterone levels decrease in a randomized soy intervention among men. Eur J Clin Nutr 60 (12): 1423-9, 2006. [PUBMED Abstract]
- deVere White RW, Hackman RM, Soares SE, et al.: Effects of a genistein-rich extract on PSA levels in men with a history of prostate cancer. Urology 63 (2): 259-63, 2004. [PUBMED Abstract]
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