China is the birthplace of soybeans and the earliest country to develop and produce soy products, with a history of soybean cultivation spanning five thousand years.
Soybeans are rich in high-quality protein, and many people enjoy soy products. However, a long-standing folk belief persists that "people with chronic kidney disease should not eat soy products."
Is this claim valid? Should individuals with chronic kidney disease truly avoid soy products? Why does this notion persist?
Soybeans as a Source of High-Quality Protein
Historically, it was widely believed that animal proteins contain higher levels of essential amino acids, offer better bioavailability, and produce fewer metabolic waste products. Conversely, soybeans and soy products were thought to be rich in non-essential amino acids, have lower bioavailability, and generate more metabolic waste.
Therefore, it was believed that patients with chronic kidney disease should avoid soybeans and soy products. However, recent studies indicate that moderate consumption of soy products may actually support kidney function recovery.
To clarify this claim, let's first examine the nutritional characteristics of proteins in soybeans and soy products. Although soy protein is plant-based, it contains higher levels of protein and essential amino acids compared to cereal grains.
Soybeans boast a protein content of 35%–40%, with a high lysine content and a favorable amino acid profile, making them a high-quality protein source.
Soy products—fermented or non-fermented foods made from soybeans, such as soy milk, tofu, and dried tofu—also serve as important dietary sources of high-quality protein.
Additionally, soybeans are low in saturated fat and high in unsaturated fat, rich in fiber and various beneficial phytochemicals such as soy isoflavones and soy peptides.
Excessive protein intake increases the metabolic burden for patients with chronic kidney disease.
When protein enters the body, it breaks down into metabolic waste products like creatinine, uric acid, and urea, most of which are excreted by the kidneys.
For individuals with chronic kidney disease, whose kidneys have reduced excretory capacity, consuming large amounts of protein significantly increases metabolic waste in the body, thereby placing additional strain on the kidneys.
Adopting a low-protein diet markedly reduces the production of metabolic waste products like creatinine and blood urea nitrogen, significantly slowing the decline in kidney function.
However, excessive protein restriction can lead to malnutrition. While protein intake must be controlled, the body still requires protein for metabolism. To meet both needs, high-quality protein sources are essential.
What dietary requirements exist for chronic kidney disease patients?
1. Limit intake of plant proteins like rice and wheat products. Instead, prioritize high-quality protein sources such as dairy, eggs, various meats, and soy protein.
3. Within protein intake limits, prioritize high-quality protein sources to meet metabolic needs and minimize tissue protein breakdown.
4. When potassium restriction is medically necessary, carefully select fruits, potatoes, potato starch, and vegetables.
5. When patients have reduced appetite, increase carbohydrates and vegetable oils in cooking to meet energy requirements.
As seen above, soy products are nutritionally rich, and soy protein is high-quality. Chronic kidney disease patients can moderately consume soy products while adhering to a low-protein diet.