A popular legume that’s grown and cultivated across the world, soy is a plant-based protein food that is consumed in many ways. It’s a mainstay in many Asian cuisines and is often used as a meat replacement in certain diets.
Soy is somewhat controversial, however, because some producers genetically modify the plant. Some claim that it can disrupt hormone levels, harm thyroid health and even contribute to cancer, while others point out that it can improve heart health, boost fertility and keep cholesterol levels in check.
Like many foods, there are both positive and negative aspects when it comes to soybeans, and some special considerations for those with specific health concerns. However, in moderation, many soy products can be enjoyed as part of a healthy diet.
Still, it’s best to select organic, fermented and minimally processed varieties and pair with a diverse range of other nutrient-dense foods to maximize the potential health benefits.
What Is Soy?
The soybean is a type of legume that is originally native to East Asia, but is now grown and cultivated all around the globe.
Apart from the edible bean itself, the soybean plant is used to produce a number of different products, including soy milk and tofu. It’s also often fermented to produce ingredients like tempeh, soy sauce and miso, which is a traditional Japanese paste made from fermented soybeans.
Soybeans are used to make a variety of processed foods as well, including many vegan meat substitutes and dairy-free yogurts and cheeses that are considered less healthful. Other compounds such as soy lecithin and soy protein isolate are often extracted from the plant and added to processed foods and supplements.
Nutrition
Soybeans are a great source of protein and provides an array of other important nutrients, including calcium and iron.
For example, a 0.2 package serving (79 g) of Vitasoy USA Azumaya firm tofu contains the following ingredients:
- Calories: 63
- Total Carbohydrates: 1.2 g
- Fiber: 0.5 g
- Sugar: 0.3 g
- Total Fat: 3.3 g
- Saturated Fat: 0.4 g
- Polyunsaturated Fat: 2 g
- Monounsaturated Fat: 0.9 g
- Trans Fat: 0 g
- Protein: 7.2 g
- Cholesterol: 0 mg
- Sodium: 18.2 mg (1% DV*)
- Calcium: 142 mg (11% DV)
- Iron: 1.03 mg (6% DV)
*Daily Value: Percentages are based on a diet of 2,000 calories a day.
Each serving of tofu also contains some manganese, selenium, phosphorus, copper and magnesium.
Benefits
Soybeans contain several powerful compounds that have been extensively studied for their beneficial effects on health, including isoflavones, plant sterols, prebiotics and more.
1. Support heart health and lower cholesterol levels
Some research has found that including plenty of soy foods in your diet may help manage cholesterol levels and promote better heart health. In a 2015 review published in British Journal of Nutrition, soy consumption was found to reduce levels of triglycerides, total cholesterol and bad LDL cholesterol while also boosting levels of beneficial HDL cholesterol.
A 2021 study also showed that fermented soy products may lower both total and LDL cholesterol.
2. Work as a menopause remedy
It may also offer several health benefits for women specifically. In particular, isoflavones have been shown to increase levels of estradiol (estrogen) in the body, which can reduce certain side effects of menopause.
In fact, one review of 19 studies found that isoflavone supplements were able to decrease the frequency and severity of hot flashes in women.
3. Assist regular menstruation and fertility
Soy protein could also promote regular menstrual cycles and enhance fertility. For example, one study out of Rome actually found that phytoestrogens helped increase the pregnancy rate among 213 women undergoing in vitro fertilization.
4. Potentially lower rates of cancer
Other studies have found that regular consumption of soy may also be tied to a lower risk of developing breast cancer, along with colorectal, prostate and lung cancer as well. The soy isoflavones appear to be particularly cancer preventing.
5. Lower the risk of type 2 diabetes
Those same soy isoflavones may also lower the risk of diabetes. A 2020 study discussed how soy helped manage the body’s blood sugar and may assist in lower type 2 diabetes risk.
6. Lower the risk of osteoporosis
Among postmenopausal females who are vulnerable to developing osteoporosis, soy isoflavones may assist in improving bone density according to a study. In fact, looking at a 2018 study, soy isoflavones may work as well as hormone replacement therapy for bone density restoration.
Risks and Side Effects
Although soy foods may be associated with several potential health benefits, there are a few side effects and risks that need to be considered as well.
For starters, isoflavones act as phytoestrogens, meaning that they mimic the effects of estrogen in the body. For this reason, many people choose to avoid soy foods due to concerns about their effect on hormone-linked cancers, such as breast cancer.
Interestingly enough, however, some studies have actually found that soy isoflavones could actually be linked to a lower risk of developing breast cancer. According to one 2016 review, higher consumption of soy products was linked to a 30 percent lower risk of developing breast cancer among Asian women.
Of course, it’s important to note that these populations typically consume non-GMO, fermented and minimally processed soy foods, which is a stark contrast to many of the highly processed products consumed in most western countries.
Because of the phytoestrogen effects of soybeans, many also wonder: Is soy bad for men? Studies have turned up mixed results on the impact of soy consumption on hormone levels for men.
For instance, one animal model published in the Journal of Endocrinology found that administering high amounts of soy phytoestrogens to rats reduced testosterone levels and prostate weight within five weeks. On the other hand, a large review in 2010 showed that consuming soy had no effect on hormone levels in men, and other studies have actually found that soy consumption may be associated with a lower risk of prostate cancer as well.
That being said, if you have thyroid issues, you may want to keep soy intake in moderation, as some studies have found that isoflavones could decrease the production of thyroid hormones in the body. A study from Loma Linda University compiled the results of 14 trials and concluded that those with thyroid problems don’t need to avoid soy foods altogether, but should be sure that they are consuming enough iodine to prevent adverse effects on health.
Allergies to soy products are also very common, with one study estimating that soy allergy affects around 0.4 percent of children. Although many people do outgrow these allergies, it’s important to avoid soy products if you have an allergy to prevent adverse side effects.
Additionally, a large portion of the soy produced in the U.S. is genetically modified, with some reports estimating that up to 93 percent of crops are genetically engineered. Selecting organic soy products is a simple way to ensure that your foods are produced from non-GMO crops.
Conclusions
- Some of the specific compounds found in soybeans have been shown to help lower cholesterol levels, improve reproductive health, decrease symptoms of menopause and reduce the risk of certain types of cancer.
- Keeping your intake in moderation and selecting non-GMO, minimally processed and fermented varieties whenever possible can help minimize any adverse effects on health and maximize the potential benefits.
