In July 1996 the health Departarnento of the United Kingdom warned that the Phytoestrogens found in the forrnulas of soy milk for infants could affect the health of these. To inform health professionals, physician in Chief, Sir Kenneth Calman, said that formulas with soy only be should be given to infants following the recommendations of a health professional. He emphasized that breast milk is the best food to protect babies of any allergies and commented that there are alternatives to soy to prescribe them babies with allergies and that they can not take breast milk.
The majority of products derived from soya and soya-based infant formulas contain a class of natural components known as Phytoestrogens, which produce a biological activity in humans and other mammals. As the name suggests, Phytoestrogens have the ability to imitate some of the actions of estrogen, the female hormone; However, Phytoestrogens also cause a wide range of other effects on the endocrine system. There is the concern that certain classes of Phytoestrogens in soy (isoflavones) have potential toxic important in the reproductive system and development, if they are provided to infants.In 1996 the governmental Committee United Kingdom Food advice asked companies investigating the Elimination of isoflavones of soy milk administered to infants, but despite the evidence that this is possible (see below) the companies not yet have driven out such research.
Concern for the health of infants
The potential biological effects in infants due to the soy isoflavones have been clearly identified, and include changes in the functions of the sexual glands, the central nervous system, thyroid gland, and patterns of behavior (1-6).
The exposure of infants to formulas soy-based, and thus to isoflavones is fairly high, 1000 times greater than that found in infants fed with milk mathematical or cow (7-9) milk-based formulas.
Comparison: Guinea pigs fed with soybean (small) versus fed without sija (large)
Isoflavones are absorbed by infants (7) and the levels in the blood plasma of infants that have been given soy-based formulas are comparable to levels that have significant estrogenic effects in experiments on animals (10).
Like many factors that negatively affect the endocrine system, the soy isoflavones may affect the proper functioning of the thyroid gland in humans. According to various documents of ´60 age, infants fed with soy milk developed goitre although bociogenicos factors were not identified at the time (11-15). Other more recent reports have identified the real and potential toxicity of soy in the thyroid gland (16-19), anti-militarists as the active factor in the soy, isoflavones. In in vitro tests, these compounds inhibit reactions catalysts of the thyroid peroxidase in concentrations that are comparable to those present in the plasma of human infants (20). Malignant goitre was found in experimental animals fed with soy (21) and there is the potential that the soy isoflavones may cause cancer in the thyroid gland of human beings.
There are reports of other biological effects of isoflavones in infants (22-23).
There are also reports on the effects of biological adults. A study on the feeding United Kingdom to premenopausal women, found that 60 g of protein of soy per day for a month, affect the menstrual cycle, and the effects of isoflavones continued for three months after completed the diet with soy. These effects were presented in levels of dosage according to body weight, which means that the doses were in an order of magnitude lower than the levels to which infants are exposed. For the latter, the high levels of exposure, along with a regular and frequent power during the day, have resulted in that infants fed with soy milk had higher levels of isoflavonoids in plasma than any other group. Therefore, infants fed with soy milk are exposed to large doses of isoflavonoids for much longer, in comparison with premenopausal women affected by the ingestion of soy, the studies mentioned.
DC made, infants who are fed with soy milk from birth can experinientar these high exposures for 12 months or longer,including periods after birth sexual differentiation critics.
So far the effects of isoflavones in women are presented as changes in the status of sex steroid hormones and the secretion of nipples (25-25). In premenopausal women, there is a clear potential for isoflavones alter fertility.
Although the study was not conclusive, identified a significant positive association between the consumption of formulas based on soy and the increasing occurrence of premature Thelarche in Puerto Rico (26).
In vitro, the sojya isoflavones are potent inhibitors of the 17-b-hidroxiesteroide Oxidoreductase (27-28) and therefore can modulate the synthesis and metabolism of estradiol and other hormones, steroids (29).
It has demonstrated the toxicity of isoflavones in the reproduction and development of different species of animals (30-34).
The toxicity levels of dietary isoflavones on animals was which caused the first alarm in the scientific community and attracted attention to the fact that soy isoflavones affected the endocrine system (35). Quail them in various animals such as leopards (34), mice (33), rats (21), (32), the sturgeon (36) and sheep (37) effects on reproduction, infertility, diseases of the thyroid gland or liver diseases caused by ingestion of isoflavones have been observed.
Elimination of isoflavones of infant formulas
In 1996, the Advisory Committee of food from the British Government asked companies manufacturers of soy-based formulas that investigate the possibility of reducing the levels of Phytoestrogens in their products. Processing standard does little to reduce the relative levels of isoflavones in infant formulas based on Soy (38-39). Isoflavones can however be eliminated with the ethanol extraction and this has been demonstrated in various documents that detail the methods for analyzing the isoflavones in soy (38-40) products. Free isoflavones from soy protein can also be used as it is the case of the chest (f), a product of the soy protein produced by the Daniels Midland Company used as control studies and trials (24). Laboratories Abbott-Ross (manufacturers of soy-based formula, isomil) developed a low formula in Phytoestrogens and reported successful tests of the product (41).
Despite all this evidence that it is possible to eliminate commercial Phytoestrogens, manufacturers of formulas based on soy for infants are reluctant to do so.
In United Kingdom, his trade Guild, the Association of manufacturers of Alirnentos children's and dietetic (IDFA in English) has informed the Food Commission processing to eliminate Phytoestrogens may affect the quality of the protein (42) - a claim that seems to go against the evidence previously filed.
It is well shown that infants are especially sensitive to factors that affect the endocrine system and for this reason are a group of high risk in terms of exposure. Therefore, any exposure of infants to these factors, including the Phytoestrogens, must be maintained at the lowest possible level. However, at present, infants fed with soy milk are subject higher than any other group of the population exposure; a situation that has led to Dr. Daniel Sheehan, Director of the Research Department on development and reproduction at the National Center for toxicological research of the FDA (Food and Drugs Administration, USA)(UU.) to observe than infants fed with formula-based soa have been put at risk, in a grand experiment in human children, without control and without any rule (43).
The risks associated with exposure to infants by Phytoestrogens are well determined and suspicions first arose a decade (44). Subsequently, the harmful effects of Phytoestrogens in soy-fed infants have been identified: in particular it is clear that infants fed Soy formulas are at real risk of chronic thyroid damage and in fact infants suffering from a malfunctioning thyroid should avoid formulas with soy and soy milk. You can pass some time until fully quantifying risks, but all risks can be avoided since the technology is available to make manufacturers reduce greatly the content of Phytoestrogens in Soy formulas.
The Food Commission considers that irresponsible Soy formulas manufacturers is continue to put infants at unnecessary risk by exposure to Phytoestrogens and has therefore requested the immediate elimination of the Phytoestrogens in Soy formulas for infants.
April 1999 Appendix: what about the traditional use of soy in infant feeding?
In Asia the soya was not used in infant feeding. In 1930 the Guy Ra Doctor of the Department of public health of the Peiping Union Medical College found: "relevant to note that he has been never observed that Peiping women use natural soy milk to feed their children." This drink is not in Peiping houses, but is sold by street vendors as a hot and very weak solution of soy protein and is usually consumed by the elderly as a replacement for the tea. Soy milk, as a complement of the diet of infants, is quite tedious and difficult to prepare. His claim is based on that has been offered recently in different health centres, but it is so alien to this community as cow's milk"(45)."
In later publications, doctor Guy reported the use of milk of soy as a food for infants. The objective of this report was the comment about the possible uses of soy milk to solve the problem of feeding infants not receiving enough milk mathematical than in a country where cow's milk is not consumed. Again Guy noted that although is "a diluted soy or milk TOU FU CHIANG on the streets of Beijing sell hot and this was ingested by the elderly instead of tea, unlike Western Nations, not soy milk is used to feed infants" (46).
Can soy cause disorders of the thyroid gland in humans?
It has been shown that soy affects the functions of the thyroid gland in humans. A study conducted by Japanese researchers concluded that ingestion of a moderate amount of soy by adult patients could cause enlargement of the thyroid gland and suppress the function of the (17).
These researchers studied the effects of surninistrar 30 g daily of soya in pickling on the function of the thyroid gland. During the investigation, it was reported that ingestion of iodine (in seaweed) was normal in all patients.
The researchers observed a significant increase in the levels of TSH in a group of 20 adults fed with soybean during 1st month (Group I) and in a group of 17 adults fed with soy for 3 months (Group 2). In two of the patients, TSH levels increased dramatically, from about 1 micro-U / mL to 6.5 or 7.5 micro-U / mL. There were no significant changes in the levels of inorganic iodine, T3 or T4 in any of the groups, but there was a significant increase in T3 F and F T4 of the patients in Group 2 after stop consuming soy.
Appreciated a not well-defined goiter and hypothyroidism in three of the patients in Group 1 and in eight of the patients in Group 2. Patients in Group 2 were also associated with hypothyroidism symptoms: constipation (53%), fatigue (53% of patients) and lethargy (41% of patients).
Goiter in 11 patients was a not well-defined goiter that was between the ranges I and 11 of enlargement. One of the patients in Group 1 developed subacute thyroiditis. The size of goiter was reduced in nine of the patients after 1 month without consuming soy but persisted in two patients. Took 6 months of treatment with T4 that reduced the size of goiter in these paclentes.
Subclinical hypothyroidism is defined as the combination of a moderately high TSH with a 14 free normal, a condition that is becoming common and which can eventually evolve towards an obvious hypothyroidism, especially in persons with antibodies quantitation. Subclinical hypothyroidism is defined as an asymptomatic condition in which reduced secretion of thyroid hormones is offset by an increase in the production of TSH to maintain a clinically euthyroid status.
This condition is of the utmost importance and its prevalence appears to be increasing. Factors in the diet can play an important role in the development of this condition. A high intake of a compound bociogeno may increase the secretion of TSH and the secretion of TSH increase is also related to the growing risk of thyroid cancer. It is worth noting that in the United States of America the frequency of malfunction of thyroid in people under 45 years of age has doubled since 1985.
Soy and breast cancer
Las people that they are consuming soy or supplements of isoflavones in the hope of reducing the risk of cancer should think twice. While consumers and health professionals are being bombarded with advertising industry, that exalts the anti-cancer properties of soy isoflavones, many cancer researchers are saying just the opposite; that the consumption of soy isoflavones may increase the risk of cancer.
For example, postmenopausal women who consume as therapy of replacement hormone (TRH) natural soy isoflavones, have increased risk of developing breast cancer. In 1996 the Doctor Nicholas Petrakis of the University of California at San Francisco, reported that "the extended usage of isolated soy protein has a stimulating effect on the breasts of premenopausal women, characterized by an increase in the secretion of fluid from the chest, the appearance of epithelial cells hiperfisticas and high levels of estradiol." "These findings suggest a stimulus estrogen from the isoflavones genistein and daidzein the contained in the soybean protein isolated". (25).
Dr. Craig Dees of the Oak Ridge National Laboratory found that soy isoflavones do that the cancer cells of the breast reproduce. It was reported that: "low concentrations of genistein may stimulate to MC-7 cells into the cell cycle" (47). Dr. Dees concluded "that the women should not consume certain foods (e.g. products derived from soya) to prevent breast cancer".
Doctor William Helferich, Illinois supports the thesis of precautions about the consumption of soy to prevent breast cancer. Recently stated that; "there is a likelihood that dietary genistein stimulates the growth of estrogen in humans with low estrogen levels endogenous circulating, such as those found in postmenopausal women dependent tumors" (48).
How much soy can be consumed without risk?
The comments made by the study of the thyroid Ishizuki clinic suggest effects important bociogenicos in patients fed with 30 g of soya a day. Based on the concentrations of isoflavones found in soy Japanese (38), 30 g of soy can contribute up to a total of 23 mg of genistein and daidzein the 10 mg. For an adult weighing 70 kg. This would be equal to the ingestion of 0.33 mg/kg of body weight of genistein and 0.14 mg/kg of body weight per day daidzein. This amount of consumption of isoflavones is approximately three times higher than the amount consumed in the Japan, which is 0.08 to 0.13 mg/kg of body weight in total genistein per day for an adult weighing 70 kg (49).
For infants fed soy-based formulas, exposure to isoflavones is much greater than any other group of the population. Infants younger than 6 months are fed Soy formulas iniciamente have an intake of up to 5.4 mg/kg of body weight of genistein and 2.3 mg/kg of body weight per day daidzein (7). For this reason, infants fed with formula of soy are exposed to levels approximately 16 times more high of isoflavonoids that Ishizuki study patients.
The concentrations of isoflavones found in products available in New Zealand (33) indicate that a diet of 500 g soymilk plus 200 g of tofu per day, could give as a result ingestion of up to a total of 135 mg 80 g of daidzein and genistein. For an adult weighing 70 kg, this is equivalent to the ingestion of 1.9 mg/kg of body weight of genistein and 1.1 mg/kg of body weight per day daidzein. This level of exposure to isoflavones is more than five times the exposure of patients in research of Ishizuki and others.
Isoflavones supplements users can consume up to 40 mg of genistein per day. For an adult weighing 70 kg. This is equivalent to 0.57 mg/kg of body weight of genistein per day which is 1.7 times more than the amount which are proven to cause effects bociogenicos.
Therefore infants fed Soy formulas, the consumers of large quantities of soy and isoflavones supplements users may have the symptoms of hypothyroidism without suspecting a connection to the diet.Unfortunately there are few data on what constitutes an appropriate level of intake of soy, but it seems that consumers in Western countries may now be consuming higher amounts of soy to the consumed as part of a traditional diet Asian.
Soy consumers should be cautious and not exceed the consumption of more than 40 mg of soy isoflavones per day. Have been observed disorder of thyroid and other biological effects in doses equal or above this level.
Approximately, 40 mg of isoflavones in can be found:
** Soy bean and soy 12-25 g (0.4-0.9 oz) flour
** Soy ground 20 g (0.7 oz)
** Cheese soy (tofu) 70-130 g (2.5-4.6 oz)
** 200-300 G (7.1-10.6 oz) soy milk
** 100 G bean sprouts (3.5 oz)
Why this information is not disseminated?
People have the right to know exactly what you are eating and how you are feeding their children. Why government agencies are reluctant to inform the public?
In June 1998, Doctor Mike Fitzpatrick met with the California Department of personnel to express its concern about soy, and soy-based formulas in particular. Received a reply in writing from the DHS, Dr. Susan Loscutoff, toxicologa who aflrmo:
"I agree that high levels of isoflavone in formulas to feed infants are cause for concern."
"I do not agree that parents have the right to know that soy-based formulas contain isoflavones and the kind of toxicity that isoflavones may cause in infants, since parents not sabrian how to interpret this information."
This is the typical response of the agencies who fear reprisals from the soya industries if Ilegaran to alert the public about potential hazards to health in relation to the soy isoflavones.
What can I do?
Send this information to health professionals and friends. Write to the State Health Department requesting information about the risks associated with the consumption of isoflavonoids
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