Soybeans, known for their remarkable plant-based protein content, are also rich in other beneficial compounds that can positively impact your health. Regular consumption might lower your risk of certain cancers and help ease the symptoms associated with menopause; however, it’s important to note that eating them in excessive amounts could lead to digestive issues. Scientifically referred to as Glycine max, soybeans or soya beans are legumes that originated in eastern Asia. They play a critical role in the diets of many Asian communities and have been part of human nutrition for thousands of years.

Currently, the majority of soybean cultivation occurs in Asia, as well as in North and South America, reflecting their global agricultural importance. In Asian cuisines, whole soybeans are commonly consumed, while in Western nations, heavily processed soybean products tend to dominate the market. A variety of soy products are available globally, including soy flour, soy protein, tofu, soy milk, soy sauce, and soybean oil, catering to diverse culinary needs and preferences.

Rich in antioxidants and phytonutrients, soybeans are associated with numerous health advantages. Nonetheless, there are ongoing discussions about the possible negative effects of their consumption.

This article provides a comprehensive overview of soybeans, covering all the essential information you need.

Nutrition Facts

Soybeans, predominantly known for their high protein content, also showcase a beneficial balance of carbohydrates and fats.

For a standard serving of 100 grams (approximately 3.5 ounces) of boiled soybeans, the nutrition facts are as follows:

  • Calories: 172
  • Water: 63%
  • Protein: 18.2 grams
  • Carbohydrates: 8.4 grams
  • Sugar: 3 grams
  • Fiber: 6 grams
  • Fat: 9 grams
    • Saturated: 1.3 grams
    • Monounsaturated: 1.98 grams
    • Polyunsaturated: 5.06 grams

Protein

Soybeans rank among the top sources of plant-based protein available. The protein content in soybeans constitutes roughly 36–56% of their dry weight. A serving size of one cup (172 grams) of boiled soybeans delivers about 31 grams of protein. While the nutritional value of soy protein is commendable, it does not quite match the quality of certain animal proteins. The predominant proteins found in soybeans are glycinin and conglycinin, which together account for nearly 80% of the total protein profile. It's noteworthy that these proteins can induce allergic reactions in susceptible individuals. Moreover, the consumption of soy protein has been associated with a moderate reduction in cholesterol levels.

Fat

Classified as oilseeds, soybeans are commonly processed into soybean oil. The fat content comprises around 18% of the dry weight, primarily consisting of polyunsaturated and monounsaturated fatty acids, with minimal saturated fat. Linoleic acid is the most abundant fat in soybeans, making up approximately 50% of the total fat content.

Carbohydrates

Low in carbohydrates, whole soybeans have a very low glycemic index (GI), which measures the impact of food on blood sugar levels post-meal. This low GI classification renders soybeans an excellent choice for individuals managing diabetes.

Fiber

Soybeans are a good source of both soluble and insoluble fiber. The insoluble fibers primarily consist of alpha-galactosides, which may cause gas and diarrhea in sensitive individuals. Alpha-galactosides are categorized as FODMAPs, which can potentially intensify symptoms of irritable bowel syndrome (IBS). Despite the potential for discomfort in some, the soluble fibers found in soybeans are widely regarded as beneficial. These fibers undergo fermentation by gut bacteria, resulting in the production of short-chain fatty acids (SCFAs), which can enhance gut health and possibly lower the risk of colon cancer.

Vitamins and Minerals

Soybeans serve as an excellent source of a diverse range of vitamins and minerals that are vital for our health. Here are some of the key nutrients they provide:

  • Molybdenum: Rich in molybdenum, an essential trace element predominantly found in seeds, grains, and legumes, soybeans contribute significantly to our dietary intake of this nutrient.
  • Vitamin K1: Known as phylloquinone, this form of vitamin K is abundant in legumes and plays a crucial role in the process of blood clotting, making it essential for maintaining healthy circulation.
  • Folate: Commonly referred to as vitamin B9, folate is involved in numerous bodily functions and is particularly essential during pregnancy for fetal development.
  • Copper: Many Western populations often have low dietary copper intake, which can negatively impact heart health if not addressed.
  • Manganese: This trace element, found in most foods and drinking water, is not as easily absorbed from soybeans due to their high phytic acid content, which can inhibit mineral absorption.
  • Phosphorus: Soybeans are rich in phosphorus, an essential mineral that is commonly found in the Western diet, contributing to bone health and energy metabolism.
  • Thiamine: Also known as vitamin B1, thiamine is involved in numerous bodily functions, including energy production and nerve function.

Additional Plant Compounds

Soybeans (soya) are abundant in a variety of bioactive plant compounds, which include:

  • Isoflavones: These antioxidant polyphenols belong to a family known for their diverse health benefits.
  • Phytic Acid: Present in all plant seeds, phytic acid (phytate) can hinder the absorption of essential minerals such as zinc and iron. However, methods like boiling, sprouting, or fermenting can significantly lower its levels in the beans.
  • Saponins: As one of the primary classes of plant compounds found in soybeans, saponins have shown potential in reducing cholesterol levels in animal studies.

Isoflavones in Detail

Soybeans are uniquely rich in isoflavones compared to many other foods. Isoflavones are distinct phytonutrients that closely resemble the female hormone estrogen, categorizing them within a group known as phytoestrogens (plant-derived estrogens). The predominant isoflavones present in soy include genistein (approximately 50%), daidzein (around 40%), and glycitein (about 10%). Interestingly, certain individuals have a specific type of gut bacteria capable of converting daidzein into equol, a compound believed to contribute significantly to many of the health advantages associated with soybeans.

Health Benefits of Soybeans

As with many whole foods, soybeans offer a variety of notable health advantages.

Potential to Lower Cancer Risk

Cancer remains one of the foremost causes of mortality in today’s world. While the consumption of soy products has been linked to increased breast tissue in women, which theoretically heightens the risk of breast cancer, a significant number of observational studies suggest that soy intake might actually lower the risk of developing breast cancer. Additionally, research indicates a protective effect against prostate cancer in men, highlighting the potential benefits of soy. Several compounds found in soybeans, such as isoflavones and lunasin, are believed to contribute to these cancer-preventive properties.

Relief from Menopause Symptoms

Menopause marks a significant transition in a woman's life, characterized by the cessation of menstruation. This phase often brings about various uncomfortable symptoms including sweating, hot flashes, and mood fluctuations, primarily due to decreased estrogen levels. Research suggests that isoflavones, which are a group of phytoestrogens present in soybeans, might help mitigate these symptoms. However, not all women benefit equally; soy appears to be effective primarily for equol producers, individuals who possess specific gut bacteria capable of converting isoflavones into equol. This compound may be the key to many of soy’s health benefits. A daily intake of approximately 135 mg of isoflavones for one week—equivalent to about 68 grams (2.4 ounces) of soybeans—was found to alleviate menopausal symptoms only in equol producers. While hormonal therapies have long been the go-to for managing menopausal discomfort, isoflavone supplements have gained popularity in contemporary treatments.

Support for Bone Health

Osteoporosis is a condition marked by diminished bone density, leading to a heightened risk of fractures, particularly among older women. The inclusion of soy products in the diet may help lower the risk of developing osteoporosis in postmenopausal women. The beneficial effects of soy on bone health are largely attributed to isoflavones. Thus, soybeans are not just rich in plant compounds that could aid in preventing certain cancers; they also hold the potential to alleviate menopause symptoms and decrease osteoporosis risk in women after menopause.

Concerns and Adverse Effects

While soybeans offer numerous health benefits, there are certain individuals who should consider limiting their intake of soy products, or perhaps even avoiding them altogether.

Impact on Thyroid Function

Excessive consumption of soy products may impact thyroid function in certain individuals, potentially leading to hypothyroidism, a condition characterized by insufficient production of thyroid hormones. The thyroid gland plays a crucial role in regulating growth and controlling the metabolic rate of the body. Research involving both animals and humans suggests that isoflavones present in soybeans can inhibit the production of thyroid hormones.

These symptoms included discomfort, drowsiness, constipation, and thyroid enlargement, all of which resolved after the study concluded. Another study focusing on adults with mild hypothyroidism reported that a daily intake of 16 mg of isoflavones for two months suppressed thyroid function in 10% of the participants. This amount of isoflavones is relatively low, comparable to consuming 0.3 ounces (about 8 grams) of soybeans daily.

Nonetheless, most research conducted on healthy adults has not identified any notable connections between soy intake and alterations in thyroid function. An analysis of 14 studies found no significant adverse effects of soybean consumption on thyroid function in healthy adults, although infants with thyroid hormone deficiencies were deemed at risk.

Flatulence and Diarrhea

Similar to many other legumes, soybeans contain insoluble fibers that may induce flatulence and diarrhea in sensitive individuals. While these side effects are not necessarily harmful, they can be uncomfortable. The fibers raffinose and stachyose, classified as FODMAPs, may exacerbate symptoms of Irritable Bowel Syndrome (IBS), a prevalent digestive disorder.

Soy Allergy

Food allergies represent a common issue arising from an adverse immune response to specific food components. In the case of soy allergy, the reaction is triggered by proteins such as glycinin and conglycinin, which are prevalent in most soy products. Despite soybeans being among the most common allergenic foods, soy allergies are relatively rare in both children and adults. For some individuals, soy products may potentially hinder thyroid function, cause flatulence and diarrhea, or provoke allergic reactions.

The Bottom Line

Soybeans, also known as soya beans, are an excellent source of protein, while also providing a balanced mix of carbohydrates and healthy fats. These legumes are packed with essential vitamins and minerals, along with beneficial plant compounds like isoflavones, which contribute to their health benefits.

Due to these properties, incorporating soybeans into your diet may help alleviate symptoms associated with menopause and lower the risk of certain cancers, including prostate and breast cancer. This makes them a valuable addition to various cuisines around the world, from Indian dishes like tofu curry to Australian soybean burgers. However, it's important to note that soybeans can lead to digestive discomfort in some individuals and may interfere with thyroid function for those who are predisposed. Therefore, moderation is key to enjoying the benefits of this nutritious food.