Despite the significant role that soyfoods can play in the prevention and / or treatment of kidney disease, osteoporosis and heart disease is the role that soyfoods can play in the prevention and / or cancer treatment that actually has attracted the interest of researchers. In recent years, many researchers have suggested that soy consumption is associated with relatively low rates of breast, ovarian and prostate cancers in countries consuming soy.
In 1990, participants of a workshop sponsored by the National Cancer Institute, National Institutes of Health, Bethesda, Maryland, identified several anticarcinogens in soybeans and recommended that it be studied the relationship between soy consumption and cancer risk (24). Much of the recent interest, because the wing is unique presence of soy isoflavones, especially genistein, one of the two primary isoflavones in soy.
The initial interest in the role of isoflavones in the prevention of cancer, was focused on its anti-estrogenic effects (25, 26). Isoflavones are weak estrogens and may oppose the actions of the most potent estrogen, natural or endogenous, through competition for binding to estrogen receptors. Recently, however, understanding the role of isoflavones in cancer prevention has evolved and new hypotheses have been proposed.
Genistein is a specific inhibitor of protein tyrosine kinase, and inhibits DNA topoisomerases and other critical enzymes involved in signal transduction.
In vitro genistein suppresses the growth of a wide variety of cancer cells (including both breast cancer cells of estrogen-dependent and independent), with ICso values generally about 5 to 40μ M (2-10μ g / ml ) (27, 28). Additionally, the geniestein inhibits angiogenesis in vitro microvascular endothelial cells in cattle, induced by the recombination of the factors basic fibroblast growth response in humans (29). It is thought that angiogenesis is necessary for tumors to grow beyond 1 to 2 mm (30).
Of the 26 animal studies recently reviewed by Messina et al, in which it has examined the relationship between soy consumption and / or isoflavones and experimental cancer in 18 (69%) found that soy reduced the development of tumors (28). Although attention has recently focused only on the role of soy for cancer prevention, there is a substantial number of epidemiological studies, mainly involving Asian populations, in which the relationship between soy consumption and cancer risk have been evaluated . This relationship was not the main focus of these studies, rather, the information consumption of soy was only part of the general examination of the possible connection between diet and cancer risk.
In a recent review of epidemiological data from 26 cancer sites in 21 individual studies involving non-fermented soy products (mainly tofu), 10 showed a statistically significant risk reduction, while 15 showed no association or were not statistically significant ( 28). Only one study found an increased risk, and this was with fried bean curd and esophageal cancer. The protective effects were observed in studies involving lung, breast, colon and stomach. Generally, the reduction in risk was associated with consumption of at least one serving of soy (tofu) per day, compared with a serving or less per week.
In both cases, work with animals and epidemiological studies are consistent with the identification of that soy can play a role in cancer prevention. Clinical studies evaluating the effects of soy consumption on intermediate indicators (prostate, breast and colon) are underway. These studies, if they prove to be favorable, will provide considerable justification, in combination with existing data for testing the effects of soy consumption and cancer resulting in high risk subjects, and / or growth and development of tumors in individuals with existing cancer.
It is important to bear in mind that while interest related to cancer and soy has focused on genistein, the isoflavone daidzein, which is present in soybeans at levels similar to genistein, is also anti-cancer (31, 32). Also, as mentioned previously, there are several components in soy isoflavones, with anticarcinogenic activity (24). Therefore, it can be seen as advantageous to use soybeans or soybean products using whole beans, preferably at individual components of soy, for any future studies in cancer
In 1990, participants of a workshop sponsored by the National Cancer Institute, National Institutes of Health, Bethesda, Maryland, identified several anticarcinogens in soybeans and recommended that it be studied the relationship between soy consumption and cancer risk (24). Much of the recent interest, because the wing is unique presence of soy isoflavones, especially genistein, one of the two primary isoflavones in soy.
The initial interest in the role of isoflavones in the prevention of cancer, was focused on its anti-estrogenic effects (25, 26). Isoflavones are weak estrogens and may oppose the actions of the most potent estrogen, natural or endogenous, through competition for binding to estrogen receptors. Recently, however, understanding the role of isoflavones in cancer prevention has evolved and new hypotheses have been proposed.
Genistein is a specific inhibitor of protein tyrosine kinase, and inhibits DNA topoisomerases and other critical enzymes involved in signal transduction.
In vitro genistein suppresses the growth of a wide variety of cancer cells (including both breast cancer cells of estrogen-dependent and independent), with ICso values generally about 5 to 40μ M (2-10μ g / ml ) (27, 28). Additionally, the geniestein inhibits angiogenesis in vitro microvascular endothelial cells in cattle, induced by the recombination of the factors basic fibroblast growth response in humans (29). It is thought that angiogenesis is necessary for tumors to grow beyond 1 to 2 mm (30).
Of the 26 animal studies recently reviewed by Messina et al, in which it has examined the relationship between soy consumption and / or isoflavones and experimental cancer in 18 (69%) found that soy reduced the development of tumors (28). Although attention has recently focused only on the role of soy for cancer prevention, there is a substantial number of epidemiological studies, mainly involving Asian populations, in which the relationship between soy consumption and cancer risk have been evaluated . This relationship was not the main focus of these studies, rather, the information consumption of soy was only part of the general examination of the possible connection between diet and cancer risk.
In a recent review of epidemiological data from 26 cancer sites in 21 individual studies involving non-fermented soy products (mainly tofu), 10 showed a statistically significant risk reduction, while 15 showed no association or were not statistically significant ( 28). Only one study found an increased risk, and this was with fried bean curd and esophageal cancer. The protective effects were observed in studies involving lung, breast, colon and stomach. Generally, the reduction in risk was associated with consumption of at least one serving of soy (tofu) per day, compared with a serving or less per week.
In both cases, work with animals and epidemiological studies are consistent with the identification of that soy can play a role in cancer prevention. Clinical studies evaluating the effects of soy consumption on intermediate indicators (prostate, breast and colon) are underway. These studies, if they prove to be favorable, will provide considerable justification, in combination with existing data for testing the effects of soy consumption and cancer resulting in high risk subjects, and / or growth and development of tumors in individuals with existing cancer.
It is important to bear in mind that while interest related to cancer and soy has focused on genistein, the isoflavone daidzein, which is present in soybeans at levels similar to genistein, is also anti-cancer (31, 32). Also, as mentioned previously, there are several components in soy isoflavones, with anticarcinogenic activity (24). Therefore, it can be seen as advantageous to use soybeans or soybean products using whole beans, preferably at individual components of soy, for any future studies in cancer
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