In one study, women with high intakes of soy isoflavones were 1. However, men may not experience the same fertility-boosting benefits 28 , In another study, soy foods were found to offer some protection against the effects of bisphenol A BPA , a compound found in some plastics believed to reduce fertility For instance, one review suggests that ingesting mg of soy isoflavones per day may reduce ovarian function and reproductive hormone levels — two important fertility factors However, most studies to date report that diets containing 10—25 mg — and perhaps even up to 50 mg of soy isoflavones per day — as part of a varied diet do not seem to have any harmful effects on ovulation or fertility Soy is rich in isoflavones, a class of compounds also referred to as phytoestrogens, or plant estrogens, due to their ability to bind to estrogen receptors in the body.
By binding to estrogen receptors in the body, soy isoflavones are believed to help somewhat reduce the severity of these symptoms. For instance, research suggests that soy isoflavones may help reduce the frequency and severity of hot flashes 33 , However, not all studies report the same benefits.
Therefore, more research is needed before drawing solid conclusions The resulting bone loss may cause postmenopausal women to develop weak and brittle bones, a condition known as osteoporosis. Some evidence suggests that intakes of 40— mg of soy isoflavones per day may reduce bone loss and improve markers of bone health in menopausal women. However, more research is needed to confirm these findings 37 , To put this into perspective, this would be the equivalent of eating around 5— However, this study suggests that premenopausal women may not experience the same benefit However, the protective benefits of soy were only observed in Asian women, while Western women appeared to experience little benefit Based on these studies, a proportion of women eating soy-rich diets may benefit from a lower risk of breast cancer.
Still, more studies are needed to determine which women may benefit the most. Soy-rich diets may also help lower the risk of other types of cancer.
On the other hand, men eating soy-rich diets may benefit from a lower risk of prostate cancer Soy-rich diets may improve heart health and lower blood pressure, blood sugar, and cholesterol levels. They may also improve fertility, reduce symptoms of menopause, and protect against certain cancers. However, more research is needed. Soybeans and foods derived from them have been part of the human diet for centuries. Nevertheless, some people worry about including soy in their diet due to the following areas of concern:.
Keep in mind that while these concerns are common, few of them are supported by sound science. Moreover, when negative effects have been observed, they often followed the consumption of very large amounts of soy. For instance, men who reported experiencing feminizing effects from soy consumed amounts up to 9 times larger than the average intake of men with soy-rich diets.
Although possible, it would be difficult for most people to eat that much soy each day The concerns above are commonly cited when it comes to soy. Generally, few are supported by strong science, and more research is needed to confirm the remaining. Generally, the less processed a soy food is, the more vitamins, minerals, and beneficial compounds it may contain. On the other hand, the more processed a soy food is, the more salt, sugar, fat, and unnecessary additives and fillers it likely contains.
Minimally processed soy foods may also offer benefits beyond those associated with their nutrient content. As a nutritionist, I see this in my own practice when I recommend soy-based foods as meals and snacks. My patients will either give me a look of fear, or a negative statement that has little evidence behind it. The truth is, not all soy foods are equal. Here are the facts you need to know about soy.
Yes, but it depends on the type. A review of the data on soy shows that whole soy sources, coming from edamame, tofu, miso and tempeh may have multiple benefits to health. Soy protein may help to reduce bad LDL cholesterol , may play a role in bone health , may help with renal function and may minimize symptoms of menopause such as hot flashes.
Perhaps the greatest benefit and the most controversial, is its link to breast cancer. Studies show that women who consume soy protein earlier in life may have a reduced risk of breast cancer later in life, and soy intake may even help with reducing the risk of breast cancer recurrence. In fact, a study from the journal Cancer found that higher isoflavones a main component in soy foods in the diet of North American women with breast cancer resulted in reduced risk of death from all causes.
Despite the data, the consumption of soy during breast cancer treatment is still controversial and more data reviewing the interaction between the isoflavones and the breast cancer treatment option tamoxifen is still needed.
Additionally, further research on women who are high risk for breast cancer and soy consumption may also be warranted. Bottom line though — the evidence for soy in the diet, as a beneficial component to breast health, is strong and there is no reason to give up whole soy sources before talking to your doctor or dietitian first.
The problem is, they alter the protein so significantly that it can become unhealthy. Soy protein is the protein found in whole soy products and is considered a complete protein since it contains all the amino acids necessary for optimal nutrition.
Oestrogen may protect women against heart disease during their reproductive years, but rates of heart disease increase after menopause. Soybeans have been shown to lower total cholesterol and LDL cholesterol levels, both known risk factors of heart disease. An analysis of clinical trials suggests 14g to 50g of soy protein can significantly reduce total blood cholesterol levels, LDL bad cholesterol levels and triglycerides, while moderately increasing HDL good cholesterol levels.
Whole soy products such as soymilk, soybeans and soy nuts have a greater effect on improving cholesterol levels than processed soy products. It is not known how this happens — it could be phytoestrogens or soy proteins working alone or together. Another reason could be, the amount of animal protein in the diet including saturated fat and cholesterol within the animal protein may be reduced and indirectly improve our blood cholesterol levels.
However, studies also show that eating soy protein without isoflavones results in only small cholesterol reductions, and isoflavone supplements alone have minimal cholesterol lowering effects. Due to their phytoestrogen content, it is thought soy can reduce menopausal symptoms such as hot flushes. This is based on observations of women in some parts of Asia, who tend to have soy-rich diets and typically fewer hot flushes during menopause than women on meat-rich diets.
The phytoestrogens in soy appear to act like a mild form of hormone replacement therapy HRT. However, compared with traditional HRT, it would take almost a year of regular soy consumption to have similar health benefits. More research is needed, but soybeans may help some women to manage menopausal hot flushes, even if only modestly. Do not take highly processed soy supplements if you have a high risk of breast cancer, or are a breast cancer survivor. Eating moderate amounts of whole soy foods appears to be healthy.
Generally, around 30 to 50mg of isoflavones is enough to offer health benefits. Examples of the average isoflavone content of some foods include:. Although there has been concern that high consumption of soy for some men and people with thyroid conditions may be risky, research suggests this is not the case.
Studies have also shown the use of soy infant formula in healthy, full-term babies does not appear to be harmful. However, infant soy formula may be harmful to premature babies and is best avoided. Check with your maternal and child health nurse or doctor. Some people do not wish to eat genetically modified GM foods. Soy products imported from the United States are the main source of GM ingredients in food sold in Australia. Some soybean crops have been genetically modified to be resistant to herbicide, but they are otherwise identical to non-GM soybeans.
Genetically modified soy is found in primary soy products such as tofu or soy flour , but it can also be found in a wide range of other foods such as chocolates, potato chips, margarine, mayonnaise, biscuits and bread.
Soy allergy can occur in some people due to a reaction to soy protein causing the immune system to react abnormally.
Soy allergies are common in babies and children. Symptoms include:. Soybeans are widely used in many food products. Lecithin food additive is made from soybeans and is often used in processed foods such as chocolate, baked goods, margarine, sauces, cheese and dairy products. Not all soy products will cause a reaction.
In fact, many people with an allergy to soy can safely eat soy lecithin, soya bean oil and some fermented soy foods as they are less allergenic than those containing raw soybeans. This page has been produced in consultation with and approved by:.
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