IS SOYA BAD FOR YOU?
Written by Slawomir (“Swavak”) Gromadzki, MPH
POSSIBLE HEALTH BENEFITS OF CONSUMING SOYA PRODUCTS
Soy became very popular all over the world after it was discovered that people living in Okinawa, Japan — regarded as one of the healthiest on earth — consumed a lot of soya foods. Although, like other pulses (legumes), soya is rich in nutrients yet its macronutrient content is somewhat different than that of other beans. Soybeans are higher in both protein and fatty acids than other pulses and are lower in carbohydrates.
Soya is full of various nutrients, cholesterol-lowering saponins and water-soluble fibre, excellent omega-3 fatty acids, vitamins and minerals such as folate and other B vitamins, magnesium, calcium, zinc, vitamin K1, potassium, molybdenum, or copper. Soy milk provides the same amount of calcium but twice the antioxidant content as cow’s milk.
Soya increases activity of three most powerful in our body antioxidant enzymes – glutathione, superoxide dismutase, and catalase. This extremely beneficial for our health antioxidant boosting action has now been linked to isoflavone genistein from soy.
When we enjoy regular consumption of this antioxidant-rich pulse, we also benefit from its phenolic acids, including ferulic, caffeic, coumaric, or sinapic acid.
Cooked soya beans, tofu and other soy foods are linked to lower rates of heart problems because they help lower cholesterol. For this reason they are recommended as healthy replacement for other less healthy foods such as animal fats, dairy, eggs, and meat products that contribute to heart attacks and strokes.
Tofu (soya curd) is also regarded as the highest source of amino acid tryptophan which is used in our body to produce serotonin – the strongest antidepressant and feel-good hormone and neurotransmitter.
Mark Messina, Ph.D., in his book The Simple Soybean and Your Health includes a promising data according to which soya isoflavones (daidzein and genistein) are beneficial for coping with alcoholism and treating malaria, or that genistein (one of soya isoflavones) has a potential to be used as a prototype drug for cystic fibrosis.
Soya is also very high in complete protein including all essential amino acids that our body needs but is unable to produce. It has the highest Protein Digestibility Corrected Amino Acid (PCDAAS) Score equal to egg white and milk protein, and superior to any other plant protein sources, making soya an ideal protein source for those on high protein fat loss diets, body builders and anyone who requires best quality, high and safe protein food. It is also important to mention that unlike dairy soya protein doesn’t lead to various health problems including increased risk of cancer or osteoporosis. Pea, hemp, and rice are often recommended as alternatives for those who are allergic to soy, but no other vegetarian source of protein is superior to soya. Hemp is often promoted as an excellent source of good quality protein, but it is inferior to soy as it is much lower in L-tryptophan and some other important amino acids. Therefore, for those who are looking for a perfect plant protein and can’t consume soya due to allergy I would recommend combination of hemp, pea and unrefined brown rice (or millet) as these foods complete each other making perfect protein similar to soya. Other pulses and Quinoa are also good sources of protein.
According to Dr Neal Bernard, “Soy products may reduce the risk of fibroids, knots of muscle tissue that form within the thin muscle layer that lies beneath the uterine lining. A study of Japanese women found that the more soy women ate, the less likely they were to need a hysterectomy, suggesting that fibroids were less frequent. In a study of women in Washington State, soy did not seem to help or hurt, perhaps because American women eat very little soy, compared with their Japanese counterparts.”
Research gives evidence soya may help reduce allergy risk and prevent and improve asthma symptoms, reduce skin wrinkles, improve mood, and suppress storage of abdominal fat.
Soya contains bioflavonoids called isoflavones often described as phytoestrogens (plant oestrogens) and powerful antioxidants at the same time. Isoflavones are found also in chick peas and other pulses (legumes), but soybeans have the highest concentration of these potent compounds. Soy contains also other isoflavones, but genistein and daidzein are the most beneficial ones.
Genistein, one of soya phytoestrogens, may accelerate new bone formation and prevent bone loss. Soya products consumption is also linked to lower bone fracture risk.
The main isoflavones in soybeans are genistin and daidzin which are converted by human gut bacterial flora into genistein and daidzein and other compounds such as 5-hydroxy-equol (from genistin), and equol (from daidzin). Equol has been shown to have the strongest estrogenic activities and it is believed that it has been largely responsible for the estrogen-like activities of soy and its isoflavones. However, there seems to be a great deal of variation among women in their abilities to metabolise genistin and daidzin, as it is dependent on environmental factors, including diet, and sufficient presence of probiotic bacteria in their intestines. Also seaweed consumption has been found to enhance intestinal production of equol from daidzein.
Soya isoflavones (daidzein and genistein) are famous for their oestrogen-regulating properties (although it may depend on one’s capacity to convert the isoflavone daidzein to equol that has greater estrogenic activity than daidzein itself). In the past, trials studying the effects of these isoflavones on hot flushes and other menopause symptoms have given mixed results, but now a new meta-analysis combining data from 17 different studies provides strong support for their efficacy. The analysis revealed that an average intake of 54 milligrams per day of soy isoflavones for between six weeks and 12 months was associated with an average 21% reduction in the frequency of hot flushes, compared with placebo.
However, soya products and supplements don’t seem to be equally effective in regulating oestrogen and alleviating menopause symptoms in women. It is so because isoflavones from soya foods and supplements can be significantly more effective in women whose colon is inhabited by probiotic bacteria able to convert soya isoflavones into equol (isoflavandiol metabolized from daidzein by bacterial flora in the intestines). Unlike endogenous estrogenic hormones such as estradiol are steroids, equol is a non-steroidal estrogen. Equol has been also suggested to be responsible for enhancing many other health benefits of soy consumption. However, some sources state that only about 30-50% of people have intestinal bacteria that make equol from daidzein. Some studies also indicate that in Japan, Korea, or China over 50%, while in Western countries only 25 to 30% of the adults are able to produce equol after eating soy foods containing isoflavones. Also vegetarians and vegans due to diet higher in fibre are more capable of converting daidzein to Equol. There are over twenty different types of intestinal probiotic bacteria that have the ability to convert daidzein into equol but two strains Eubacterium ramulus and Flavonifractor plautii are particularly active in this process. Both species are normally highly prevalent in healthy human gut but due to numerous factors including antibiotics, diet high in sugar and deprived of fibre many women today are low in probiotic bacteria and therefore may experience less or even no benefits from soya flavonoids. For this reason it is highly recommended to use soya isoflavones together with good probiotic formulas such as ColiProbio or UltraProbio.
Since the same soya isoflavones (daidzein and genistein) are potent antioxidants they also help remove free radicals preventing them from causing gene mutations in our cells, thus reducing the risk of various cancers. People today are brainwashed with the idea that consuming these phytoestrogens is dangerous and may contribute to various problems including breast cancer. But the opposite is true as these isoflavones are actually powerful antioxidants (particularly genistein) and research has repeatedly demonstrated that they are very beneficial and protect against breast cancer. Being a weak form of oestrogen, soya isoflavones compete at estrogen receptor sites, blocking the stronger oestrogen (naturally produced by the body) from working with full strength. Since high blood levels of oestrogen increase risk of breast cancer; daidzein and genistein may provide protection against this disease.
If you want to learn more about other numerous benefits of consuming soya products and using soya isoflavones in the form of supplements popular GreenMedInfo website included a long and constantly growing list of over 400 abstracts based on soy research >
Today, however, we are repeatedly warned to avoid soya products, including soya milk, tofu, edamame (cooked soya beans), and products made with soy flour. Some claim that even fermented soya foods such as miso and tempeh should be avoided.
It is therefore very important to find out whether soya is really so bad for us and if all the negative claims about it are based on true science.
On one website I have found a claim according to which, “the oestrogen in soy formulas has been known to cause baby girls to develop breast buds.”
It is true that infant girls and boys can both develop swollen tissues that resemble tiny breasts, but they are caused by the mother’s hormones coming across the baby’s placenta (just before the baby is born), and they disappear with time. According to Heidi Murkoff, B.S.N., “Baby may also seem to be making milk coming out of nipples but it is superficial too and caused by hormone exchange from mother to baby.”
Yes, infants may sometimes develop breast buds yet it is not caused by soya milk but mother’s hormones. My daughter as an infant was on a soya milk formula for a long time and she never developed this problem. The same is true about other infants who instead of consuming mother’s milk were fed with good quality soya milk formulas. Of course there is no better food for infant’s than mother’s milk but good quality soya milk alternatives are much healthier and safer than cow milk formulas.
In 1998, K. O. Klein, from the Dept. of Clinical Science at the A. I. DuPont Hospital for Children stated that soya-based infant formulas have been used for over 60 years to feed millions of infants, with absolutely no indication of thyroid or other endocrine problems. The same scientist also reported that according to the medical research, “Growth is normal and no changes in timing of puberty or in fertility rates have been reported in humans who consumed soy formula as infants.”
ARE SOYA ISOFLAVONES PLANT OESTROGENS?
According to another popular misconception the two soya isoflavones (daidzein and genistein) are similar to natural body oestrogen. Although those isoflavones are often called phytoestrogens (plant oestrogens), they are actually not even related to oestrogens or any other human hormones. There is no relation at all between the two as oestrogens (estradiol, oestrone and estriol) are steroid hormones produced by the endocrine glands and found only in mammals, flavonoids (flavones), on the other hand, are plant pigments.
Nevertheless, is true that soya isoflavones (daidzein and genistein) can somehow mimic natural body oestrogen and increase its levels. Unfortunately, what people are not told is they do it in an intelligent and safe way, without boosting the hormone when it is already normal. They only regulate oestrogen levels and can even block it preventing oestrogen from going too high!
BREAST CANCER AND OTHER PROBLEMS
Since soya products contain isoflavones (mainly genistein and daidzein) that can increase blood levels of oestrogen (female sex hormone) we are warned to avoid these isoflavones as they can dangerously raise oestrogen levels in the body. In women it is supposed to increase the risk of breast cancer, heart attack, stroke, cervical cancer, PCOS (polycystic ovary syndrome) and other hormone imbalance-related disorders. This claim is based on the fact that although oestrogen gives many important benefits in humans, it also naturally promotes proliferation of cells, and therefore, at higher levels, may increase risk of some cancers by stimulating cells to multiply faster.
Well, even if it is true that daidzein and genistein in soya may act like oestrogen in the body, yet they do it at a very small fraction of the potency of oestrogen, and besides, soya isoflavones, although have the ability to boost oestrogen, can at the same time lower or regulate this hormone instead of increasing its level when it is already normal or high.
According to Marji McCullough, ScD, RD Dr. strategic director of nutritional epidemiology for the American Cancer Society, “While isoflavones may act like estrogen, they also have anti-estrogen properties. That is, they can block the more potent natural estrogens from binding to the estrogen receptor. In addition, they stop the formation of estrogens in fat tissue and stimulate production of a protein that binds estrogen in the blood (to make it less able to bind to the receptor). Besides, they also have anti-oxidant and anti-inflammatory properties and work in other ways to reduce cancer growth.” So, the truth is soya isoflavones daidzein and genistein boost oestrogen only when it is low and can lower it when it is too high!
It means they do not increase the risk of breast cancer or other mentioned above problems. The opposite is true, as being antioxidants they actually help to prevent cancer and other conditions.
There is no honest scientific evidence to back up the idea that soya causes breast cancer. Even though there are some animal studies that seem to shown mixed effects on breast cancer with high doses of soy supplements, studies in humans have not shown harm from eating soy foods. Wise and moderate consumption of good soy products appears not only safe but very beneficial, and may even lower breast cancer risk. Epidemiological studies, in which large numbers of healthy women have participated and reported details about their dietary habits and were followed for years, have revealed no association between soy and breast cancer and often even gave evidence of protective association. It means that women who ate more soya foods had less breast cancer.
According to the American Journal of Clinical Nutrition (July, 2012), “Eating 1-2 servings of whole soy can reduce the risk of breast cancer recurrence by 25%”. One study even showed that regular consumption of just one cup of soya milk a day lowered overall mortality among breast cancer patients by up to 38%.
Women who have higher levels of oestrogen hormone may actually gain a protective effect from higher doses of soy isoflavones. Medical research suggests soy isoflavones may even protect against side effects of higher than normal levels of estrogen, which is a risk factor for breast cancer in postmenopausal women. For example, scientists attempted to evaluate the effects of different doses of soya isoflavones in the presence of either low or high levels of oestrogen. In the low oestrogen environment, even at very high doses, isoflavones didn’t lead to increased cell proliferation (increased breast cancer risk). When isoflavones were not used at all or when they were taken in low doses in the high oestrogen environment, the breast cell proliferation was higher. However, when scientists used high levels of dietary soy isoflavones (daidzein and genistein) they managed to block oestrogen effects in breast tissue, thus preventing breast cancer! This discovery suggests that postmenopausal women on HRT with higher than normal levels of estrogen may be benefited by consuming soya foods and using soya isoflavones in the form of supplements. On the other hand, there is some evidence that women who already have breast cancer and are on anti-cancer drugs should avoid soya isoflavones supplements as they seem to block effectiveness of the drug.
TRUE CAUSES OF BREAST CANCER
After researching possible causes of breast cancer we can find out that it is never good organic and non-GMO soya products but the following: meat, dairy, sugar, refined carbohydrates, bad fats, free radicals, candida, stress, toxins, bad diet, stimulants (including wine, caffeine products or chocolate), pollution, bad lifestyle, lack of exercise, lack of sleep, dehydration, avoiding sunlight, nutritional deficiencies (especially vitamin D deficiency), diet low in antioxidant, etc. Also being obese after menopause contributes to breast cancer because oestrogen is formed in fat tissue and is the major source of oestrogen after menopause.
DAIRY AND BREAST CANCER
Some sources and experts suggest that the most dangerous among mentioned above factors increasing breast cancer risk seems to be cow’s milk and dairy products!
According to the 2015 Abstract issued by Journal of Breast Cancer, “Dairy consumption was inversely associated with the risk of developing breast cancer and this effect was dependent on the dose, dairy-type, and time.” In Asia, where tofu, soymilk, and other soy products are commonly consumed and cow’s milk is not a normal part of the diet, breast cancer is much rarer than in Europe and America.
Dr. Campbell (professor of nutritional sciences at Cornell University) in his famous and bestselling book The China Study wrote: “What protein consistently and strongly promoted cancer? Casein, which makes up 87% of cow’s milk protein, promoted all stages of the cancer process. What type of protein did not promote cancer, even at high levels of intake? The safe proteins were from plants, including wheat and soy“.
Published in 2103, 12-year study of more than 1,800 breast cancer survivors found eating one or more portions of high-fat dairy (milk, cream, cheese or yogurt) a day was associated with 49% increased risk for dying from breast cancer than women who avoided the foods.
While soy is the source of phytoestrogens that can regulate oestrogen levels it does not contain oestrogen. On the other hand, animal foods including dairy contain oestrogen as animals are not only regularly fed with synthetic growth hormones, but they also produce their own natural oestrogen which is found in meat and dairy products.
On 3rd of August 2015 The Daily Mail – UK published an article with the following title, “Cure Breast Cancer By Avoiding All Milk Products. Give up dairy to beat cancer.” According to that article, “A leading scientist given just months to live changes her diet and is still alive nearly 20 years later after eliminating dairy and all animal foods from her diet.” Professor Jane Plant, a specialist in environmental carcinogens, in her book about breast cancer included the following statement: “Undoubtedly, the best anti-cancer diet would be completely vegan (a diet completely free from animal foods: no poultry, beef, pork, seafood, egg, cow’s milk, yogurts or cheese). If you want to reduce your risk of breast (or prostate) cancer, become a vegan, but on no account become a dairy-eating vegetarian. If any anti-cancer diet includes any kind of dairy products, ignore it.”
British women are more likely to die of breast cancer than elsewhere in Europe. In UK one in ten women is diagnosed with breast cancer while one epidemiological study from the seventies showed the same disease affected only one in 10,000 Chinese women. In UK and US an average person consumes 250kg of dairy product per year and in China only 32kg per year (although it went up from 15kg in 2006). At the same time consumption of soya products in China is much higher. Unfortunately, popularity of dairy products in China is constantly growing. As a result the risk of breast and other cancers increases too. Also when Chinese women move to UK, US or Australia and switch to Western diet within one generation they end up with similar breast cancer rates.
After careful investigation of all the claims accusing soya of causing breast cancer and other dangerous problems Nathan Zassman wrote that, “the anti-soy ‘madness’ is fuelled by the American Dairy Association and the Weston A. Price Foundation, through articles written by Sally Fallon and Mary Enig, Ph.D. Both organizations stand to lose the most money due to soy consumption.”
After reading many articles on breast cancer with correlation to both dairy and soya I have made the same discovery and agree that soya criticism is mainly muddied by the dairy industry’s agents. Since wealthy dairy manufacturers realised their profits slip away to other forms of milk they do their best to condemn soya while hiding dark truth about their own products using sponsored by them controversial and obviously biased studies on both soya and dairy. It is true that soya manufacturers also do their best to promote their products but unlike their dairy competition they have huge amount of unbiased scientific research to back up their claims.
INCREASED RISK OF HEART ATTACK AND STROKE
Women are warned to avoid soya because by raising oestrogen it may increase risk of not only breast cancer but also heart attack or stroke.
Also in this case the opposite is true as unlike meat and dairy soy products have not only anticancer properties but can also lower bad cholesterol. Researchers in the College of Medicine at the University of Kentucky analysed results from 43 previously published studies on soya protein and risk of coronary heart disease (CHD) and found an overall decreased risk of CHD when 30 grams of soy protein was consumed on a daily basis. Decreased LDL cholesterol was found to be an important part of this lowered risk.
IODINE DEFICIENCY AND THYROID PROBLEMS
Soya was also accused of causing iodine deficiency and goitre (enlarged thyroid). The connection between soy consumption, iodine deficiency and goitre (goiter) was first mentioned in 1960 in The New England Journal of Medicine. However, by now, there have been numerous studies which never confirmed the causal correlation between soya and thyroid problems.
It is true some studies revealed decreased TPO (thyroid peroxidase) activity when fed isolated daidzein and genistein (isoflavones found in soya that react with TPO), but although some TPO activity was lost, yet there was no negative effect on thyroid function and thyroid hormone levels.
The studies that seem to show goitrogenic effect of soya isoflavones were performed on rats with low levels of iodine. It is not soya consumption that is responsible for thyroid problems but again unhealthy lifestyle and iodine deficiency (very common today due to soil depletion). That is why both humans and animals may experience symptoms of hypothyroidism only when they are mainly fed with foods (including soya products) which are deprived of iodine. In this way, poorly designed studies in which animals are fed with low in iodine soya may lead to underactive thyroid. Unfortunately, instead of blaming iodine deficiency for causing the problem they conclude that soya isoflavones are the culprit.
So, you can consume soya product and use soya isoflavones in the form of supplements, without fearing they may lead to iodine deficiency and underactive thyroid, but at the same time you must make sure you provide your thyroid with regular supply of natural iodine in the form of kelp tablets.
Concerning another claim according to which soya is supposed to lead to infertility, the 2003 Department of Health’s committee on toxicity report revealed there was no evidence that people who regularly consume even high quantities of soya products, such as people living in China or Japan, have impaired their fertility. Since China is the world’s most populous nation that have been consuming soya for over 3,000 years claiming it causes infertility is just ridiculous.
A large study by Boston Fertility Center has even demonstrated that regular consumption of soya products by women significantly improved birth rates for couples undergoing fertility treatment.
Soya does not reduce fertility in men too. A 2010 review of the results from many independent scientific studies stated that, “neither soy foods nor isoflavone supplements alter bioavailable testosterone concentrations in men.” According to the same meta-analysis, isoflavone supplementation had no effect on sperm count, concentration, or motility. It simply means men’s testosterone is not negatively affected by consuming soy foods.
FEMINIZING EFFECT ON MEN
Another alleged unwanted side effect of regular consumption of soya products is that it is supposed to give more feminine characteristics in men. Soya is to cause this effect by boosting oestrogen and lowering testosterone through the action of soya isoflavones genistein and daidzein. In reality, however, clinical studies show isoflavones (genistein and daidzein) affect neither testosterone nor circulating oestrogen levels. The best proof of this is the fact that Asian males who are on a soy rich diet, isoflavones have not been found to have feminizing effects.
GYNAECOMASTIA (MALE BOOBS OR ENLARGED BREASTS)
According to one weird report a 60-year-old man developed sexual dysfunction and boobs as a result of consuming about 3 litters of soya milk a day for six months. Although one source suggests it might be possible that very high consumption of soya products (at levels ten times higher than normal for several months) may contribute to some hormonal changes over time, yet there was no reference included to prove it. However, even if it is true no one should consume three litres of soya milk a day. I myself use organic soya milk (free from bad calcium, sugar or maltodextrin) from time to time, but no more than about 1 litre per week, as I consume also home-made almond milk. In addition, we don’t know if that individual’s diet was free from other foods such as dairy products which are famous for causing hormonal imbalance and increasing oestrogen. According to the Estrogen Dominance Guide, “Cow’s milk and dairy can constitute as much as 80% of dietary intake of oestrogen. Cows produce milk while they are pregnant and nursing, so their oestrogen levels are significantly higher. Dairy livestock are also regularly given doses of hormones to increase their growth and milk production. That’s why conventionally raised meats and dairy can contribute to gynecomastia (boobs or enlarged breasts).”
There is not enough scientific data to prove long-term overconsumption of soya can or can’t lead to gynecomastia, but there is a strong evidence that moderate soya intake appears to be perfectly safe. Besides, if soya was so effective in enlarging breasts we would know a lot about it by now as women all over the world spend fortune on breast augmentations.
PHYTIC ACID AND MINERAL DEFICIENCY
Soya contains phytic acid which is supposed to bind with minerals in our body thus leading to their deficiencies. The truth, however, is there is not enough scientific evidence to prove this point. In addition, soya is lower in phytic acid than any legume or grain. We also know that the same phytic acid can be very beneficial as it reduces the risk of cancer, heart disease, osteoporosis, depression, and other health problems.
ONLY FERMENTED SOYA FOODS ARE HEALTHY?
Asian dietary habits are commonly used to support another idea according to which only fermented soy foods are healthy and safe.
Also this claim can’t be sustained by honest investigation because the most popular soy product regularly consumed in Asian countries, especially China, is tofu and cooked soya beans and not fermented soya foods such as natto or tempeh. In Japan tofu and dried soya beans are at least as popular as fermented soya foods. According to research by Ginny Messina, R.D., “In Japan, about half of soy consumption comes from the fermented foods miso and natto, and half comes from tofu and dried soybeans.”
Also organic, free from sugar, calcium carbonate, maltodextrin and preservatives soya milk is a perfectly safe and healthy food to consume with moderation and alternatively with other plant milks.
Scientists from the University of Southern California compared the results of eight studies, and concluded that women who have a half-cup of tofu or a cup of soya milk each day have about a 30% reduced risk of developing breast cancer, compared with women who consume little or avoid these foods.
Some people may be allergic to soya but this possible issue is also overblown as it is not a common problem (probably not higher than 0.2%). For instance in the U.S. it could be as low as 0.1% (290-580,000 individuals). In addition, there are researchers who conclude that soya may even help reduce allergy risk and prevent and improve asthma symptoms.
Well, is soya good or bad for us? We don’t need to be rocket scientists in order to conclude that it depends on what soya products we consume and how often we do it.
It is true that genetically modified foods including soya don’t seem to be safe but a non-GMO and organic soya or certain foods based on it, consumed moderately, are perfectly healthy and even very beneficial. However, it probably doesn’t mean that even healthy soya foods are perfectly safe if they are consumed too often, which by the way is true with regards to other good plant foods. Unfortunately, there are many vegetarians and vegans who have tendencies to consume way too much of soya every day as it is offered in many different forms including soya milk, tofu, soya protein, or other popular soya-based dairy and meat substitutes. On the other hand, there is no evidence that moderate consumption of non-GMO cooked soya beans, organic unsweetened soya milk or tofu as well as fermented soya products contribute to any health problems unless you are allergic or intolerant to certain substances or ingredients found in soya products.
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