Is soy healthy? There is so much information to be found about soy on the internet – much of it confusing, and much of it based on outdated information or internet myths. Find out the truth about soy in this post.
Oh, the much-maligned soybean. How could a little bean have such a bad reputation? As someone who loves tofu and tempeh and soymilk (all made from soybeans), I can’t tell you how often I’ve been warned that “soy is bad for you”. My friend’s husband wouldn’t touch soy, for fear it would give him the much-feared “man boobs”. How can there be so much hate for such a little bean?
Is soy healthy? Science-backed Facts About Soy
So what is soy exactly? Soy comes from the soybean, which is native to East Asia but is now grown throughout the world. It is a legume – a bean in this case – that grows in a pod.
(Fun fact I learned while researching this post…..ever wondered why soybeans are green, but tofu and soymilk are white? It turns out that tofu is made from white soymilk, and white soymilk is made from mature soybeans – which are white or beige).
So let’s start with what is GOOD about soy!…
The Benefits of Soy:
First, let’s start with some of the benefits of whole food soy products (these are minimally processed and organic soy foods such as tofu, tempeh, edamame, soy milk, miso, soy sauce, soy nuts, and natto).
- Soy is a complete protein, containing all nine essential amino acids.
- It is an excellent source of calcium, iron, omega 3s, B vitamins, fiber, potassium, and magnesium
- Soy is high in fiber, has no cholesterol, and is also low in saturated fats (unlike animal protein), making it a heart-healthy food.
- Soy is much lower in calories than comparable animal proteins
So soy looks like it’s pretty healthy. Why is it so controversial?
One big reason is the pro-dairy and pro-meat industries. The plant-based and vegan food industry is growing exponentially, and this has the multi-billion dollar (in the U.S.) meat and dairy industry scared. A lot of the misinformation about “the dangers of soy” is spread by meat and dairy marketers. They have spent millions lobbying against climate action and creating doubt in people about global warming.
So let’s take a closer look at some of the questions and concerns that have been going around about soy, and find out if they are legitimate (because I understand why they can be scary!).
Should women eat soy? “Is soy healthy for women and girls? I’ve heard soy causes breast cancer?”
Whole soy foods (like edamame, tofu, and soy milk) contain isoflavones. Isoflavones have a very healthy effect on the body. Isoflavones are phytoestrogens – plant chemicals that can have estrogen-like effects in the body. And THIS is where the controversies over soy began.
Some early studies showed that soy isoflavones could increase the risk of breast cancer. There were two problems with these studies, however. The first problem is that these were not human studies, but rather studies on rats. And rats process soy very differently than humans do. The second problem was that the doses of soy isoflavones given to the rats in these studies were concentrated, and much higher than what a human would ever eat.
In HUMAN studies, the soy isoflavones have either no effect at all on study participants, or prove to have a protective effect against breast cancer. In fact, women who consume the most soy have a 30% lower risk of developing breast cancer in comparison with women who consume no soy (the thought is that soy isoflavones,block or inhibit the stronger, cancer-promoting natural estrogen found in the blood).
And in Asian countries – where soy is typically consumed daily – breast cancer rates are much lower than they are in the United States. Yet when Asians move to the U.S. and start eating like Americans do (with little to no soy), their risk of breast cancer escalates.
Pre-teen and teenage girls:
And what about pre-teen and teenage girls who consume soy…is it safe for them? Studies have shown that girls who eat soy may have a lower risk of developing breast cancer in adulthood. It seems that soy is also a breast cancer preventative when consumed while breast tissue is still forming.
And should menopausal women eat soy? A 12-week study, published by the North American Menopause Society in the journal Menopause, found that a plant-based diet rich in soy reduces hot flashes by 84% (from five hot flashes per day to less than one per day). And nearly 60% of the women in this study became totally free of moderate-to-severe hot flashes.
Also, studies have shown that the phytochemicals found in soy isoflavones have been found to prevent bone loss in menopausal women.
Should men eat soy?: “I’ve heard that soy increases estrogen in men and reduces testosterone. I might end up with ‘man boobs’!”
Gynecomastia in men (development of enlarged breast tissue in men – aka “man boobs”) has a few causes including genetics, obesity, and hormones. But soy is not one of them. Studies on actual men (not animals) have shown that soy has no “feminizing” effects on men, and will not increase the size of breast tissue in men (or women for that matter). Soy will also not reduce testosterone levels.
(If men want to avoid “feminizing hormones”, then they might want to avoid cow’s milk. Participants in a study – which consisted of men, women, and children – showed an increase in both female hormones – estrogen and progesterone – after drinking dairy milk).
On the other hand, the second most common cancer in men is prostate cancer. And men who consume the most soy have about a 29% less risk of prostate cancer, compared to men who do not consume soy products. And the incidence of prostate cancer is also lower in Asian populations where soy foods are widely and regularly consumed. And studies of Seventh-Day Adventists, have found that drinking two glasses of soy milk per day appears to lower prostate cancer risk by 70 percent!
Should people with thyroid problems eat soy?: “I have hypothyroidism and heard that soy can make things worse. Is this true?”
Soy has NOT been found to cause thyroid problems. However, in people diagnosed with hypothyroidism and on thyroid hormone medication, a study has found that soy products may interfere with thyroid medication absorption. This does not mean that soy should be avoided if you have hypothyroidism or Hashimotos (as I do!). If thyroid medication is taken on an empty stomach (as directed) 4 hours before consuming any soy products, then any interference in absorption can be avoided. (And the same guidelines apply to other products that can impair thyroid medication absorption – including concentrated iron and calcium supplements, and antacids that contain calcium or aluminum hydroxide.)
For thyroid health, everyone should make sure to get enough dietary iodine. The thyroid gland uses iodine from food to make thyroid hormones, so low iodine levels can affect thyroid function.
So, soy really IS healthy?
Soy IS healthy AND a disease preventative in most people. But you should be aware of the following:
- Focus on organic, non-GMO, minimally processed soy products – including tofu, tempeh, edamame, soy milk, miso, soy sauce, soy nuts, and natto (products that are certified organic are considered non-GMO due to labeling standards)
- Avoid highly processed soy products – including soy protein isolate (which may be found in certain ‘mock meats’ or protein powders). These products are so heavily processed, most of the nutrients and fiber that make soy healthy have been removed.
- Like many other foods (such as wheat or corn), soy can be an allergen. So avoid eating soy if you think you may be allergic and see a doctor for a potential allergy test.