Despite these criticisms, Newbold stands by her data. Ultimately, a mouse and a rat are not the human, though. You just have to accept it and be as careful with your extrapolations as possible. Further controversy surrounds the fact that most of the epidemiologic studies of Asian populations involved whole soy foods, but animal and human intervention studies have generally used soy concentrates or isolated isoflavones; some animal studies used pure genistein.
This difference may have obscured what the health effects of soy actually are. In Expert Panel Report on the Reproductive and Developmental Toxicity of Genistein, a March review of the literature on this compound, an expert panel convened by the CERHR scrutinized what has been learned about human exposure to genistein and the associated reproductive and developmental consequences.
The most highly exposed adult population was Japanese, with a daily average intake of 0. Based on the conclusions presented at a meeting held on 15—17 March , the panel found little cause for concern about human exposure to genistein.
However, no consideration was made for the amount of genistin found in the diet or how much of it is hydrolyzed in the digestive system to genistein. Like genistein, daidzein in soy exists primarily in linkage with a sugar molecule. This complex, daidzin, is hydrolyzed and the sugar molecule removed in the gut. Daidzein can also be conjugated to glucuronic acid or sulfate in the gut and liver. It may also be converted to equol suspected of having a higher estrogenic potency than the original daidzein by gastrointestinal bacteria.
Thomas Clarkson, a professor of comparative medicine at the Wake Forest University School of Medicine, points out that although soy protein has a very large beneficial effect on cardiovascular health in monkeys, the effects are much less clear in women. Daidzein metabolism may be the key. There have been only a few studies that have looked exclusively at glycitein, the third soy isoflavone, but those have not been on health effects.
There are indicators from a couple of recent in vitro studies that glycitein may be protective of bone. Most glycitein research has focused on determining how to detect the compound, and its estrogenicity and metabolism.
Unlike soy milk, which is sometimes mistakenly—and tragically—used in its place, soy formula contains soy protein isolate supplemented with additional amino acids, minerals, vitamins, and fats necessary to support infant growth and development. Steroid hormones affect myriad processes during development, including the formation of hormone-responsive tissues and organizing and activating effects in the central nervous system.
Some researchers are therefore concerned that isoflavones from soy-based infant formula might perturb that system, with long-term consequences. Isoflavones were detected in blood, showing that infants absorbed the compounds from the intestine. This was not a given, since the infant gut is significantly different from the adult gut and continues to develop through the first year. Biological effects are plausible but not necessarily detrimental.
For example, in a study comparing the short-term, long-term, and multigenerational effects of soy protein isolate, casein, and whey on the health and development of rats, a group led by Badger found that soy protein isolate was protective against chemically induced breast cancer.
This study appeared in the 1 May issue of the International Journal of Toxicology. In advising caution in feeding infants soy formula, several groups cite a study led by Richard Sharpe at the Centre for Reproductive Biology in Edinburgh, Scotland. The soy-fed marmosets had comparatively lower testosterone levels and higher numbers of Leydig cells per testis.
However, a follow-up study published in April , also in Human Reproduction , indicated no obvious effects on reproduction. In this study, adults who had been in a controlled feeding study during infancy completed a telephone interview about their health, development, and reproductive history. A follow-up letter to the JAMA editor pointed out that both the Strom study and a retrospective epidemiological study published in the April issue of the Journal of the American College of Nutrition suggested that consumption of soy formula could adversely affect immune function in children.
For their part, both Jefferson and Newbold caution against using their results to determine the safety of soy formula, although they believe their findings of adverse effects in rodents provide strong evidence that concern is warranted. Their findings are not definitive proof that soy formula is harmful, however. Given the limited evidence for the health effects of soy isoflavones in infants, pediatric and health organizations in several countries suggest caution in feeding soy to infants and young children.
Soybeans are a major allergen, and a significant percentage of children who are sensitive to dairy are also sensitive to soy. However, other experts indicate that soy formula is an adequate source of nutrition for infants with more than 40 years of apparently safe use. During the study, now in its fourth year, children receive multiple in-depth checkups, including assessments of bone development and health, imaging of reproductive tissues, and assessments of brain development and function, metabolism, growth, development, and body composition.
The research team aims to enroll pregnant women, whose children will be followed from birth through puberty. Data analysis is currently under way. Your doctor may advise that it's best to skip soy altogether if estrogen is at play in this case. Women undergoing in vitro fertilization who have environmental exposure to BPA are more likely to get pregnant if they also ate soy. Consuming over mg of soy isoflavones the equivalent of 6-ounces uncooked tempeh or 16 cups soy milk daily was linked to reduced ovarian function, found a Journal of Nutrition review.
As for soy solving those annoying and disruptive hot flashes that accompany menopause? It might help, but not for everyone. Among women whose bodies produce the soy metabolite equol, those who ate the most soy experienced significantly fewer hot flashes and night sweats compared to those who ate the least, found one Menopause study.
If it helps, you produce equol. Early research suggested that soy could help lower levels of bad cholesterol. In general, replacing animal foods with plant foods like soy lowers saturated fat intake and ups fiber intake, both of which are help your heart.
In other words, swapping that steak out for tofu or tempeh is a heart-smart move. But having steak followed by a bowl of soy ice cream for dessert is not a heart-protective move.
But if you have an underactive thyroid, you might want to watch how much soy you eat. The evidence is still far from conclusive, but experts still advise to wait at least four hours after consuming soy to take your thyroid medicine.
Soy frankenfoods like meat analogs, soy bars, soy yogurts, or protein powders usually only contain soy protein isolates, rather than nutrition from the whole soybean. As for how often you should eat soy? As with all foods, moderation is the way to go. Generally, three to five servings of minimally processed soy foods per week are perfectly fine, Bhatia says. Product Reviews. Home Ideas. Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional.
The information and materials contained on this website are not intended to constitute a comprehensive guide concerning all aspects of the therapy, product or treatment described on the website.
All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions and to ascertain whether the particular therapy, service, product or treatment described on the website is suitable in their circumstances. The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website.
Skip to main content. Healthy eating. Home Healthy eating. Soybeans and soy foods. Actions for this page Listen Print. Summary Read the full fact sheet. On this page. Nutrition profile of soybeans Soy products Soybeans and phytoestrogens Health benefits of soy foods Amount of soy for health benefits Tips for increasing soy intake Other foods containing phytoestrogens Health risks of soy and babies Genetically modified soy products Soy allergy Where to get help.
Nutrition profile of soybeans Soy is a high-quality protein. The soybean is: high in fibre high in protein low in saturated fat cholesterol free lactose free a good source of omega-3 fatty acids a source of antioxidants high in phytoestrogens.
Soy products Soybeans can be consumed in many ways. Health benefits of soy foods Research suggests that soybeans and soy foods have a range of health benefits. Coronary heart disease and soy Having a diet rich in soy foods is linked with a lower risk of cardiovascular disease , including stroke and coronary heart disease.
Soybeans and menopause Due to their phytoestrogen content, it is thought soy can reduce menopausal symptoms such as hot flushes. Other health benefits of soy Other possible health benefits of soy foods include: lowered blood pressure improvements to blood vessels, such as greater elasticity of artery walls improved bone health protection against some cancers including breast cancer improved cognitive function and visual memory.
Amount of soy for health benefits Generally, around 30 to 50mg of isoflavones is enough to offer health benefits. Examples of the average isoflavone content of some foods include: half a cup of soybeans — 40 to 75mg isoflavones quarter cup of soy flour — 45 to 69mg isoflavones one ml glass of soy drink — 15 to 60mg isoflavones one g block of tofu — 13 to 43mg isoflavones one g block of tempeh — 41mg isoflavones one container of soy yoghurt — 26mg isoflavones two slices of soy bread — 7 to 15mg isoflavones teaspoon of soy sauce — 0.
Tips for increasing soy intake If you want to increase your intake of soy: Choose whole soy foods like soymilk, tempeh, soy bread and tofu. Check ingredient lists to make sure the soy foods you buy are made from whole soybeans and not soy isolates.
Make sure products such as cereals contain soy protein and not just added isoflavone. Other foods containing phytoestrogens Foods other than soy that contain phytoestrogens include: wholegrain cereals — like oats, wheat, corn, barley, rye and buckwheat nuts and seeds — such as almonds, linseed, flaxseed, sunflower, pumpkin and sesame sprouts — alfalfa oils — extra virgin olive oil other legumes — chickpeas, lentils and kidney beans.
Health risks of soy and babies Eating soy foods as part of your normal diet is generally more beneficial than harmful. Genetically modified soy products Some people do not wish to eat genetically modified GM foods. Soy allergy Soy allergy can occur in some people due to a reaction to soy protein causing the immune system to react abnormally. Symptoms include: itching tingling sensation of the mouth and lips flushed skin nausea diarrhoea wheezing and shortness of breath hives dizziness and confusion.
Foods to avoid If you have a soy allergy, seek advice from your doctor. Always read food labels and avoid: soymilk soybean soya soy nuts and soy sprouts soy sauce tofu miso tempeh tamari.
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