Soybeans are a type of legume native to East Asia. It has become an important food in vegetarian and vegan diets, so it is interesting to know the effects on the body.
Various soy products are currently available, including flour, protein powder, tofu, milk, soy sauce, and oil. Soybeans contain antioxidants and phytonutrients that are linked to various health benefits. However, concerns have been raised about potential adverse effects.
Soybeans are mainly made up of protein, but they also contain good amounts of carbohydrates and fats. If we take 100 grams of boiled soy as a reference, its nutritional values are:
- Energy: 173 calories
- 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 grams
- Polyunsaturated: 5.06 grams
- Omega-3: 0.6 grams
- Omega-6: 4.47g
Soybeans are among the best sources of plant-based protein . The protein content of soybeans is 36 to 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 animal protein.
The main types of protein in soybeans are glycinin and conglycinin, which make up about 80% of the total protein content. However, these proteins can trigger allergic reactions in some people. Soy protein consumption has been linked to a modest decrease in cholesterol levels.
Soybeans are classified as oilseeds and are used to make soybean oil. Fat content is about 18% dry weight, mainly polyunsaturated and monounsaturated fatty acids, with small amounts of saturated fat. The predominant type of fat in soybeans is linoleic acid , which makes up about 50% of the total fat content.
Being low in carbohydrates, whole soybeans have a very low glycemic index , which is a measure of how foods affect the rise in blood sugar after a meal. This makes it a suitable food for people with diabetes.
In addition, it contains a good amount of soluble and insoluble fiber . Insoluble fibers are mainly alpha-galactosides, which can cause flatulence and diarrhea in sensitive people. Alpha-galactosides belong to a class of fibers called FODMAPs, which can exacerbate the symptoms of irritable bowel syndrome. Despite causing unpleasant side effects in some people, the soluble fibers in soy are generally considered healthy.
Like most whole foods, soybeans have a number of beneficial health effects.
lowers blood pressure
Soybeans and foods made from them are generally rich in arginine, an amino acid that is believed to help regulate blood pressure levels. It is also rich in isoflavones, another compound believed to offer blood pressure-lowering benefits.
However, it’s not clear whether these small blood pressure-lowering benefits apply to people with normal and elevated blood pressure levels. Some studies suggest that both may benefit, while others suggest that only people with high blood pressure would experience this effect.
Lowers the risk of cancer
Cancer is one of the leading causes of death in modern society. Eating soy products is linked to an increase in breast tissue in women, which is hypothesized to increase the risk of breast cancer. However, most observational studies indicate that the consumption of soy products may reduce the risk of breast cancer.
Studies also indicate a protective effect against prostate cancer in men. Several compounds in this legume, including isoflavones and lunasin, may be responsible for possible cancer-preventive effects.
Exposure to isoflavones early in life may be particularly protective against breast cancer later in life.
Some research suggests that women who eat diets rich in soy may benefit from improved fertility. In one study, women with a high intake of isoflavones were 1.3 to 1.8 times more likely to give birth after fertility treatments than those with a lower intake of isoflavones.
However, these findings are not universal. For example, one review suggests that taking 100 mg of isoflavones daily can reduce ovarian function and levels of reproductive hormones, two important fertility factors.
However, most studies to date report that diets containing 10 to 25 mg, and perhaps even up to 50 mg, of isoflavones per day, as part of a varied diet, do not appear to have deleterious effects on ovulation or fertility.
Relieves symptoms of menopause
Menopause is the period in a woman’s life when menstruation stops. It is usually associated with unpleasant symptoms, such as sweating, hot flashes, and mood swings, which are caused by a drop in estrogen levels.
Studies indicate that isoflavones, a family of phytoestrogens found in soy, can relieve these symptoms. Soy products do not affect all women in this way. It only seems to be effective in so-called equol producers, those that have a type of intestinal bacteria capable of converting isoflavones into equol.
Daily intake of 135 mg of isoflavones for 1 week, equivalent to 68 grams of soy per day, reduced menopausal symptoms only in equol producers. Although hormonal therapies have traditionally been used as a treatment for menopausal symptoms,
Improves bone health
Osteoporosis is characterized by reduced bone density and an increased risk of fractures, especially in older women. Soy consumption may reduce the risk of osteoporosis in women who have gone through menopause. Interestingly, these beneficial effects appear to be caused by isoflavones.
The low levels of estrogen experienced during menopause can cause calcium to leach out of the bones. The resulting bone loss can cause postmenopausal women to develop weak and brittle bones, a condition known as osteoporosis.
Some evidence suggests that taking 40 to 110 mg of soy isoflavones per day may reduce bone loss and improve markers of bone health in menopausal women. However, more research is needed to confirm these findings.
Although this food has a number of health benefits, some people should limit their consumption or avoid them altogether.
Suppression of thyroid function
High consumption of soy products can suppress thyroid function in some people and contribute to hypothyroidism, a condition characterized by low production of thyroid hormones.
The thyroid is a large gland that regulates growth and controls the rate at which the body expends energy. Human studies indicate that isoflavones can suppress the formation of thyroid hormones. So regular consumption of this food and its derivatives or isoflavone supplements can cause hypothyroidism in sensitive people, especially those with an underactive thyroid gland.
flatulence and diarrhea
Like most other legumes, soybeans contain insoluble fibers, which can cause flatulence and diarrhea in sensitive individuals. Although not harmful to health, these side effects can be unpleasant.
Raffinose and stachyose fibers, which belong to a class of fibers called FODMAPs, can worsen symptoms of IBS, a common digestive disorder. If we have irritable bowel syndrome, it is recommended to avoid or limit soy consumption.
Food allergy is a common condition caused by a harmful immune reaction to certain food components. Soy allergy is caused by proteins (glycinin and conglycinin) found in most soy products.
Although soy is one of the most common allergenic foods, soy-related allergy is relatively uncommon in both children and adults.
Soy and foods derived from it have been part of the human diet for centuries. However, some people worry about some side effects:
- Estrogen-mimicking effects . Soy isoflavones are often thought to mimic the female reproductive hormone estrogen. Although they are similar in structure to this hormone, soy isoflavones have weaker and slightly different effects than estrogen.
- Feminizing effects in men . Some are concerned that isoflavones may reduce the production of the male hormone testosterone. However, human studies find a weak link between the two.
- Danger for babies . Some fear that soy formula may negatively affect brain, sexual, thyroid, or immune development. However, studies generally fail to see any long-term negative effects of formula in healthy babies.
- Transgenic. Soy is usually genetically modified. The transgenic can contain less nutrients and more herbicide residues than the conventional or organic. More research is needed on the long-term health effects of the GM version.
- Antinutrients. This food contains compounds that can decrease the body’s ability to absorb the vitamins and minerals they contain. Soaking, sprouting, fermenting, and cooking are all ways to reduce these antinutrient levels.