Three most common myths about soy
1. Soy consumption is one of the main causes of deforestation
I decided to put this myth about soy first because I hear it all the time. Especially when I mention, that one of the main reasons I am leading a plant-based lifestyle is to help our planet. Just recently, we heard the news saying that the Amazonian rainforest is being burned down to make space to grow soy. So actually, this soy myth is partly true. But it is not the human soy consumption that is demanding such a high soy production, it is the meat and dairy consumption. According to the latest data, animal agriculture is responsible for 91% of the destruction of the Amazon rainforest and around 80% of the global soy crops are used to feed livestock. Only about 3% of soy is estimated to be consumed by humans in the form of soy products, and the rest is used to make oil.
2. Most of the soy is genetically modified (GMO)
This myth about soy is also partly true, but again, not when it comes to the soy for human consumption. In most parts of Europe, they don’t even use GMO soy for humans. There are a lot of soy products that are also classified as organic and the organic classification requires non-GMO ingredients by law. But livestock is mostly fed GMO soy. The problem with genetically modified plants is that most genetic modifications are made so that the plant sustains higher concentrations of pesticides and herbicides. These toxins then accumulate in tissues and secretions of animals that are fed with GMO soy, so those consuming meat and dairy products actually suffer from it the most.
3. Soy contains estrogen
This is another myth about soy, that scares many people. Soy does contain a substance called phytoestrogen, which is a plant form of estrogen. But phytoestrogens are not the same as estrogens and a human body does not react to phytoestrogens the same way as it does to estrogens. There are two types of estrogen receptors in the human body, they are called alpha and beta receptors. Estrogen attaches to alpha receptors and phytoestrogens attach to beta receptors. Because there are different ratios of alpha and beta receptors in different parts of a human body, there are different ways in which the phytoestrogens in soy can benefit our health. Let’s look at a few of them below.
Actual benefits of soy consumption
Soy consumption decreases the risk of breast cancer and other gynecological types of cancer
Increased estrogen levels are a known risk factor for breast cancer development and progression. That is why many women fear soy products, as they think the phytoestrogen might increase their estrogen levels. But as it turns out, the opposite is true. Soy and the phytoestrogens in soy actually help decrease estrogen levels, as they block estradiol (a primary human estrogen) to bind to the receptors. So the activation of beta receptors by phytoestrogens in breast tissue actually has an anti-estrogenic effect. Even after the breast cancer diagnosis, soy intake was associated with reduced mortality and reduced recurrence. That might also explain, why Chinese an Japanese women, coming from the countries that are known for consuming high amounts of soy, have such low rates of breast cancer. Soy consumption is especially protective for those women that have genetic predispositions for breast cancer. Women who ate the most soy also had 30% less endometrial cancer and appeared to have cut their ovarian cancer risk almost in half.
Soy phytoestrogens decrease menopausal hot flushes
When women go into menopause, their estrogen production decreases up to 95%. As we learned, lower estrogen levels reduce breast cancer risk. But the production of estrogen does not go down to 0, because other tissues, like for example fat cells, can produce estrogen. Could soy foods help to protect women from menopausal symptoms, too? This study shows that that might indeed be the case. Soy added daily to the diet of menopausal women substantially reduced the frequency of hot flushes. Again it also turned out, that hot flushes are much less common in countries like Japan, where soy consumption is higher.
Soy consumption lowers the risk of prostate cancer
Soy consumption also seems to help men when it comes to prostate cancer. Multiple studies have shown that soy consumption dramatically decreases the risk of prostate cancer in men. The reduced risk for prostate cancer and lower prostate cancer progression might also be associated with a variety of plant-based foods since it seems to be lowest in parts of the world where they eat predominantly a plant-based diet and consume the least dairy products.
Actual sources of dietary estrogen
The estrogen found for example in chickens and cows is identical to human estrogen called estradiol. That is why meat and dairy consumption actually increase levels of estradiol, which is linked to cancer initiation and progression. All farm animals, especially pregnant ones, also secrete large amounts of estrogen through their feces and secretions, which goes into our rivers, seas, and drinking water, affecting both marine and land life. The presence of animal hormones in food has already been connected to several health problems.
Which soy foods and how much should you have?
Which soy foods are the best?
As with all kinds of foods, whole soy foods are most preferable. The best choice would be whole soybeans, edamame, soy nuts, then soy milk, yogurt, tofu, tempeh, miso and soy flour (not defatted). And as always, it is a good idea to stay away from isolates, soy protein isolates in this case, found in many mock meats and protein powders, which of course, are not considered whole foods.
How much soy should you have?
Some studies showed that if you eat too much soy, it could potentially neutralize some of its beneficial effects. But how much is too much? There is no exact number, but based on the studies we have to date, Dr. Michael Greger recommends up to 5 servings per day.
Who shouldn’t have soy
Soy is not advised for people with soy allergies, which are pretty rare. Soy allergy is about 40 times more rare than our most common allergy, which is an allergy to dairy milk.