The health benefits of soybeans are highly regarded from both the perspectives of Traditional Chinese Medicine (TCM) and Western Medicine. TCM posits that soybeans are sweet in flavor and neutral in nature, neither warming nor drying. They are known to invigorate the spleen to promote dampness drainage, nourish the blood to address deficiencies, and detoxify. They are considered highly effective for individuals with a weak spleen and stomach, those who are thin and have a poor appetite, or those suffering from dampness impediment and muscle spasms, edema, or difficult urination.
From a Western medical standpoint, soybeans are celebrated for their high-quality protein, which is rare in the natural world as a source of complete protein. They contain all eight essential amino acids required by the human body, making them particularly beneficial for protein supplementation. Unlike animal proteins, soybeans are cholesterol-free, allowing for protein intake without the simultaneous intake of cholesterol, a significant risk factor for cardiovascular diseases. Furthermore, soybeans are rich in bioactive substances such as isoflavones and saponins. These compounds play an indispensable role in maintaining human health; for instance, soy isoflavones, being precursors to estrogen, are effective in alleviating the discomfort associated with menopause in women.
While soybeans are nutritious, how they are consumed is a science in itself. Soybeans are a high-protein food, containing approximately 35% protein. However, most of this protein is trapped within the soybean cells. As anyone with basic biological knowledge knows, a key distinction between plant and animal cells is the presence of a cell wall; cells with a cell wall are plant cells. This robust cell wall tightly encapsulates the abundant protein. Since the human body cannot digest the cell wall, the protein becomes difficult to absorb and utilize.
During cooking and chewing, only a portion of the cell walls are broken, releasing some protein, while a significant amount remains trapped within the cell walls. Ultimately, the vast majority of this protein is excreted as waste, which can be considered a loss. Our ancestors developed several ingenious methods to solve this problem. Although they may not have understood the underlying scientific principles, the wisdom of their solutions is often remarkable. Making tofu from soybeans is one excellent method to improve their utilization. When soybeans are ground, their cell walls are thoroughly destroyed, and the protein is naturally released. Consequently, the human body's rate of digesting and absorbing this protein increases dramatically, from about 50% to approximately 90%, thereby greatly enhancing the nutritional value of soybeans.
The principle for making soy milk is the same, with only slight variations in the preparation method. Additionally, fermentation can also break down the cell walls to improve protein utilization. However, it is important to note that while the protein utilization rate of whole soybeans is low, their other water-insoluble components still offer considerable health benefits. Therefore, consuming whole soybeans is also highly significant. Similarly, the okara (soy pulp) produced after grinding has excellent health-promoting properties and can be used as a filling or in other ways; it should not be discarded.