Soybeans or soybeans ( Glycine max ) are a variety of legumes that grow in East Asia. The benefits and harms of soybeans are widely debated, since an initially healthy product may not be very healthy due to gene modification. And soy is one of the first crops that is susceptible to it.
However, soybeans are an important component of Asian diets and have been consumed for thousands of years. Today they are mainly grown in Asia, as well as in South and North America.
In Asia, soybeans are often eaten whole. But soy products with a high degree of processing are much more common in Western countries.
A variety of soy products are available, including soy flour, soy protein, tofu, soy milk, soy sauce and soybean oil.
Soybeans contain antioxidants and phytonutrients that are associated with various health benefits. However, concerns were expressed about possible adverse effects.
In this article we will consider what soybeans are, the benefits and harms to health.
Nutrients in Soybeans
Soybeans are mostly protein, but also high in carbohydrates and fats.
100 grams of boiled soybeans contain:
- Calories: 173
- Water: 63%
- Protein: 16.6 grams
- Carbohydrates: 9.9 grams
- Sugar: 3 grams
- Fiber: 6 grams
- Fat: 9 grams
- Saturated: 1.3 grams
- Monounsaturated: 1.98 g
- Polyunsaturated: 5.06 g
- Omega 3: 0.6 grams
- Omega-6: 4.47 g
Soybeans are some of the best sources of vegetable protein. The protein content in soybeans is 36–56% of dry weight. One cup (172 grams) of boiled soybeans contains about 29 grams of protein.
The nutritional value of soy protein is good, although the quality is not as high as that of animal protein ( 6 ).
The main types of protein in soybeans are glycine and conglycinin, which account for approximately 80% of the total protein content. These proteins can cause allergic reactions in some people ( 4 , 7 ).
Soybeans are classified as oilseeds and are used to produce soybean oil.
The fat content is approximately 18% dry weight – mainly polyunsaturated and monounsaturated fatty acids with a small amount of saturated fat.
The predominant type of fat in soybeans is linoleic acid, which accounts for approximately 50% of the total fat content.
Low in carbohydrates, soybeans have a very low glycemic index (GI), which is a measure of how foods affect blood sugar levels after meals ( 12 ).
This low GI makes soybeans suitable for people with diabetes.
Alpha-galactosides belong to a class of fibers called FODMAP, which can exacerbate the symptoms of irritable bowel syndrome (IBS) ( 15 ).
Despite causing unpleasant side effects in some people, soluble fiber in soybeans is generally considered beneficial.
Thus, fiber in soybeans is good for some and harm for others. If you have problems with your intestines, it is recommended that you limit your use of soy.
Soybeans are a very rich source of vegetable proteins and fats. Moreover, their high fiber content is good for your intestinal health.
Vitamins and Minerals
Soybeans are a good source of various vitamins and minerals, including:
- Molybdenum. Soybeans are rich in molybdenum, an indispensable trace element that is mainly found in seeds, grains and legumes ( 18 ).
- Vitamin K1. A form of vitamin K found in legumes is known as phylloquinone. It plays an important role in blood coagulation ( 19 ).
- Folate. Also known as vitamin B9, folate performs various functions in the body and is considered especially important during pregnancy ( 20 ).
- Copper. Dietary copper consumption is often low in western populations. Deficiency can have an adverse effect on heart health ( 21 ).
- Manganese. Trace is found in most foods and drinking water. Manganese is poorly absorbed from soybeans due to its high phytic acid content ( 22 ).
- Phosphorus. Soybeans are a good source of phosphorus, an essential mineral widely distributed in the Western diet.
- Thiamine. Also known as vitamin B1, thiamine plays an important role in many body functions.
Soybeans are a good source of several vitamins and minerals, including vitamin K1, folate, copper, manganese, phosphorus and thiamine.
Other plant compounds
- Isoflavones. The family of antioxidant polyphenols, isoflavones, has a diverse health effect.
- Phytic acid. F Itat or phytic acid found in all plant seeds, affects the assimilation of minerals such as zinc and iron. Levels of this acid can be reduced by boiling, germinating, or fermenting beans.
- Saponins. It was found that saponins are one of the main classes of plant compounds in soybeans that lower cholesterol in animals.
Soybeans contain more isoflavones than other regular foods ( 27 ).
Isoflavones are unique phytonutrients that resemble estrogen – the main female sex hormone. In fact, they belong to a family of substances called phytoestrogens (plant estrogens).
The main types of isoflavones in soy are genistein (50%), daidzein (40%) and glycitein (10%) ( 23 ).
Some people have a special type of intestinal bacteria that can convert daidzein to equol, a substance that is thought to be responsible for many of the health benefits of soybeans. It is expected that people whose bodies can produce equal will receive much more benefit from soy consumption than those whose bodies cannot ( 28 ). The percentage of such people is greater in Asian populations and among vegetarians than in the general western population ( 29 , 30 ).
Soybeans are a rich source of various biologically active plant compounds, including isoflavones, saponins and phytic acid. Isoflavones, in particular, mimic estrogen and are responsible for many beneficial and harmful health effects of soybeans.
Soybean Health Benefits
Like most whole foods, soybeans have a number of health benefits.
May lower cancer risk
Cancer is one of the leading causes of death in modern society.
The use of soy products is associated with an increase in breast tissue in women, hypothetically increasing the risk of breast cancer ( 31 , 32 , 33 ). However, most observational studies show that consumption of soy products can reduce the risk of breast cancer ( 34 , 35 ).
A number of soy compounds, including isoflavones and lunazin, may be responsible for potential antitumor effects ( 39 , 40 ). Exposure to isoflavones at a young age can be especially protective against breast cancer at a later age ( 41 , 42 ).
Keep in mind that this evidence is limited to observational studies that indicate a link between soy consumption and cancer prevention, but do not prove a causal relationship.
Relieving Menopause Symptoms
Menopause is the period in a woman’s life when menstruation stops. This is often associated with unpleasant symptoms – such as sweating, hot flashes and mood swings – that are caused by a decrease in estrogen levels.
Interestingly, Asian women, especially Japanese women, are less likely to experience menopausal symptoms than Western women. Dietary habits, such as higher consumption of soy products in Asia, can explain this difference.
Soy products do not affect all women in this way. Soy, apparently, is effective only in the so-called equal products – those who have the type of intestinal bacteria that can convert isoflavones into equal.
A daily intake of 135 mg of isoflavones for 1 week – the equivalent of 68 g of soybeans per day – reduced the symptoms of menopause ( 45 ). While hormone replacement therapy has traditionally been used to treat menopausal symptoms, isoflavone supplements are widely used today ( 46 ).
Osteoporosis is characterized by a decrease in bone density and an increased risk of fractures, especially in older women.
Soybeans contain plant-based compounds that can help prevent breast and prostate cancer. Moreover, these legumes can reduce the symptoms of menopause and reduce the risk of osteoporosis in postmenopausal women.
Soybeans harm and contraindications
Despite the benefits, some people need to limit their consumption of soy products or completely abandon them. Since eating soy can have negative health effects.
High consumption of soy products can suppress thyroid function in some people and contribute to hypothyroidism, a condition characterized by low levels of thyroid hormone production ( 53 ).
The thyroid gland is a large gland that regulates growth and controls the rate at which your body expends energy.
One study among 37 Japanese adults found that eating 1 ounce (30 grams) of soy each day for 3 months caused symptoms associated with suppressed thyroid function. Symptoms included discomfort, drowsiness, constipation, and an enlarged thyroid gland – all of them disappeared after the end of the study ( 56 ).
Another study among adults with mild hypothyroidism showed that taking 16 mg of isoflavones every day for 2 months suppressed thyroid function in 10% of participants ( 55 ). The amount of isoflavones consumed was quite small – equivalent to consuming 0.3 ounces (8 grams) of soybeans per day ( 57 ).
An analysis of 14 studies did not reveal significant side effects of soy consumption on thyroid function in healthy adults, while children born with thyroid hormone deficiency were considered at risk ( 58 ).
In short, regular consumption of soy products or isoflavone supplements can lead to hypothyroidism in sensitive people, especially those who have an inactive thyroid gland.
Flatulence and Diarrhea
Although not harmful to health, these side effects can be unpleasant.
Belonging to a class of fibers called FODMAP, raffinose and stachyose fibers can worsen symptoms of IBS, a common digestive disorder ( 15 ).
If you have IBS, it might be a good idea to avoid or limit your consumption of soybeans.
Food allergies are a common condition caused by a harmful immune response to certain components in foods.
Soy allergies are caused by soy proteins — glycine and conglycin — found in most soy products.
In some people, soy products can suppress thyroid function, cause flatulence and diarrhea, and cause allergic reactions.
In the article, we examined the benefits and harms of soybeans, confirmed by scientific facts. Summarize.
Soybeans are a rich source of all macronutrients – protein, fat and carbohydrates. They also contain a large amount of various vitamins, minerals, and beneficial plant compounds such as isoflavones.
For this reason, regular consumption of soy can alleviate the symptoms of menopause and reduce the risk of prostate and breast cancer.
However, they can cause digestive problems and suppress thyroid function in susceptible people.