Glycine max, commonly known as soybean, is a crucial legume native to East Asia, extensively cultivated for its versatile and nutritious beans. Recognized globally for its high protein and oil content, soybeans play a pivotal role in both human nutrition and various industrial applications. This crop is instrumental in addressing global food security challenges due to its ability to adapt to diverse agricultural environments.

Botanical Classification

Kingdom: Plantae
Clade: Angiosperms
Class: Eudicots
Order: Fabales
Family: Fabaceae
Genus: Glycine
Species: G. max

Plant Characteristics

As a member of the Fabaceae family, Glycine max exhibits typical leguminous features with its bushy growth form. Plants vary significantly in size, influenced by genetic variety and environmental conditions, ranging from compact, low-growing cultivars to taller, more robust types. The leaves are trifoliate, composed of three oval leaflets, and the plant blooms with small, self-fertile flowers that can be white, pink, or purple. The resulting pods generally contain two to four oval or spherical beans, each packed with nutrients. Notably, the roots form symbiotic associations with Bradyrhizobium bacteria, enabling effective nitrogen fixation that enriches soil fertility by converting atmospheric nitrogen into more usable forms.

Chemical Composition and Structure

Soybeans are a powerhouse of nutrition, predominantly known for their high protein content, which makes up approximately 36% of the beans' dry weight. They are also a significant source of oil (approximately 20% of dry weight), rich in polyunsaturated fats, including linoleic and linolenic acids. Beyond macronutrients, soybeans are a good source of isoflavones, particularly genistein and daidzein, which mimic estrogenic activity and are researched for their possible antioxidant, anticarcinogenic, and cardioprotective properties.

How to Cultivate It

Cultivating Glycine max effectively requires attention to several agronomic practices:

1. Soil: Prefers well-aerated, well-drained loamy soils with a pH range of 6.0 to 6.8.
2. Light: Full sunlight is essential for optimal growth and yield.
3. Water: Regular watering is crucial, especially during the critical growth phases of flowering and seed development. However, the plants are somewhat drought-tolerant once established.
4. Temperature: Thrives in warm temperatures, with optimal growth occurring between 20°C to 30°C. Soybeans are sensitive to frost and require a frost-free growing season.

Uses and Benefits

The global reliance on soybeans extends beyond their dietary benefits. In the food industry, soybeans are processed into various products like tofu, soy milk, and soy sauce, which are staples in many vegetarian and vegan diets. Additionally, soybean oil is widely used in cooking and as an ingredient in industrial products like paints, plastics, and biofuels. The residual soy meal post-oil extraction is a high-protein feed for livestock, contributing significantly to the animal husbandry sector.

Applications

• Culinary: The versatility of soybeans makes them a staple in global cuisines, adapting to various culinary techniques.
• Industrial: Soybeans contribute to sustainable practices by providing bio-based alternatives to petroleum products.
• Medicinal: The health benefits of soybeans, particularly their role in reducing cholesterol levels and potentially lowering the risks of certain cancers, have led to increased interest in their dietary inclusion.

Environmental and Safety Considerations

The cultivation of Glycine max is linked to significant environmental debates, particularly concerning the expansion of soy cultivation into biodiverse regions like the Amazon rainforest. The widespread adoption of genetically modified soybeans raises concerns about biodiversity loss, pesticide resistance, and the health implications of consuming GM foods. Sustainable agricultural practices, including crop rotation, reduced pesticide use, and integrated pest management, are critical in mitigating these impacts and promoting environmental stewardship.

Studies

Soy contains several polyphenol compounds, especially isoflavones, which have positive effects on human health, but their presence in percentage varies depending on the type of soy.

Isoflavones (classified as phytoestrogens) have shown positive potential against cardiovascular disease, diabetes, cancer. osteoporosis and neurogenerative disorders. In the soybean, 12 different types were identified divided into:

• aglycones  (daizein, glicitein, genistein)
• beta-glucosides (daidzin, glicitin, genistin) (1)

In 1999, the FDA recognized soy proteins with some protection against coronary heart disease and authorized the following posology: 25 grams of soy protein per day as part of a low-fat, cholesterol-low diet.

In 2017, the FDA announced its intention to review the authorization for lack of scientific data as only 19 studies confirmed the usefulness of soy in reducing coronary risk, while 27 studies did not support this positive thesis.

It's a rather controversial food.

On the one hand, some studies draw attention to isoflavones present in soy that help defend the cardiovascular system by regulating cellular and enzymatic functions in situations such as inflammation, thrombosis and atherosclerotic progression (2).

On the other hand, it is feared that it may cause damage,  especially as a contributing cause for Alzheimer's disease, if ingested in the form of an industrial product. This study analyses the problem (3).

However, a certain amount of post-2017 scientific studies confirm the positive activity of soy bea on human health.

In a 20 km cycling race, a fermented soybean extract improved the performance of athletes both in terms of power and speed (4).

Patients with type 2 diabetes achieved improved blood conditions, increased brachial blood flow, improved endothelial function, increased total serum antioxidants and lipid profile. There was no significant effect on blood pressure and HDL cholesterol (5)

Soy and its isoflavones have a positive influence on mortality risks associated with cancer and cardiovascular disorders (6).

Soy studies

References______________________________________________________________________________________

(1) Orts A, Revilla E, Rodriguez-Morgado B, Castaño A, Tejada M, Parrado J, García-Quintanilla A. Protease technology for obtaining a soy pulp extract enriched in bioactive compounds: isoflavones and peptides. Heliyon. 2019 Jun 22;5(6):e01958. doi: 10.1016/j.heliyon.2019.e01958. PMID: 31294110; PMCID: PMC6595185.

Abstract. This work presents a new bioprocess process for the extraction of bioactive components from soy pulp by-product (okara) using an enzymatic technology that was compared to a conventional water extraction. Okara is rich in fiber, fat, protein, and bioactive compounds such as isoflavones but its low solubility hampers the use in food and fertilizer industry. After the enzymatic attack with endoproteases half of the original insoluble proteins were converted into soluble peptides. Linked to this process occured the solubilization of isoflavones trapped in the insoluble protein matrix. We were able to extract up to 62.5% of the total isoflavones content, specially aglycones, the more bioactive isoflavone forms, whose values rose 9.12 times. This was probably due to the increased solubilization and interconversion from the original isoflavones. In conclusion, our process resulted in the formulation of a new functional product rich in aglycones and bioactive peptides with higher antioxidant potency than the original source. Therefore, we propose that the enzymatic extraction of okara bioactive compounds is an advantageous tool to replace conventional extraction.

(2) González Cañete N, Durán Agüero S. Isoflavonas de soya y evidencias sobre la protección cardiovascular. Nutr Hosp. 2014 Jun 1;29(6):1271-82. Spanish. doi: 10.3305/nh.2014.29.6.7047. 

Abstract. Soya isoflavones represent a group of non-nutritive, bioactive compounds, of non-steroidal phenolic nature that are present in soy bean and derived foods. They share with other compounds the capacity of binding to estrogenic receptors from different cells and tissues so that they may act as phytoestrogens. The current interest in these compounds comes from the knowledge that in Asian populations with high levels of their consumption the prevalence of cancer and cardiovascular disease is lower, as compared to the Western countries populations. This cardiovascular benefit would be the result not only of the modulation of plasma lipids, which is a widely studied mechanism. This paper reviews the published evidence about the beneficial effects of soya isoflavones and the different mechanisms of action that would benefit cardiovascular health and that surpass the mechanisms traditionally approached such as the modulation of plasma lipids, and that implicate the regulation of cellular and enzymatic functions in situations such as inflammation, thrombosis, and atherosclerotic progression.

(3) Roccisano D, Henneberg M, Saniotis A. A possible cause of Alzheimer's dementia - industrial soy foods. Med Hypotheses. 2014 Mar;82(3):250-4. doi: 10.1016/j.mehy.2013.11.033. 

(4) Seeley AD, Jacobs KA, Signorile JF. Acute Soy Supplementation Improves 20-km Time Trial Performance, Power, and Speed. Med Sci Sports Exerc. 2020 Jan;52(1):170-177. doi: 10.1249/MSS.0000000000002102. 

Abstract. Introduction: Isoflavones, a chemical class of phytoestrogens found in soybeans and soy products, may have biological functions similar to estradiol. After binding with ERβ or perhaps independently of estrogen receptors, isoflavones may augment vascular endothelial relaxation, contributing to improved limb blood flow....Conclusions: Ingestion of a fermented soy extract supplement improved sprint-distance performance through improvements in both power and speed. For those with great aerobic fitness, soy supplementation may help to decrease cardiac demand alongside performance improvement.

(5) Sedaghat A, Shahbazian H, Rezazadeh A, Haidari F, Jahanshahi A, Mahmoud Latifi S, Shirbeigi E. The effect of soy nut on serum total antioxidant, endothelial function and cardiovascular risk factors in patients with type 2 diabetes. Diabetes Metab Syndr. 2019 Mar-Apr;13(2):1387-1391. doi: 10.1016/j.dsx.2019.01.057. 

(6) Nachvak SM, Moradi S, Anjom-Shoae J, Rahmani J, Nasiri M, Maleki V, Sadeghi O. Soy, Soy Isoflavones, and Protein Intake in Relation to Mortality from All Causes, Cancers, and Cardiovascular Diseases: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies. J Acad Nutr Diet. 2019 Sep;119(9):1483-1500.e17. doi: 10.1016/j.jand.2019.04.011.