Soy Protein Foods: Types and Nutritional Value
Soy protein foods are products derived from soybeans that contain significant amounts of protein and include traditional foods like tofu, tempeh, and miso, as well as processed products such as soy flour, soy protein concentrate, soy protein isolate, and texturized vegetable protein. 1
Types of Soy Protein Foods
Traditional Soy Foods
- Tofu - Available in silken, firm, and extra firm varieties; contains 4-8g protein per serving 1
- Tempeh - Fermented soy product
- Miso - Fermented soybean paste; contains 4g protein per 2 tablespoons 1
- Edamame - Whole immature soybeans; contains 11g protein per 1/2 cup 1
- Soymilk - Contains 7g protein per cup 1
- Soynuts - Roasted whole soybeans; contains 12g protein per ounce 1
Processed Soy Protein Products
- Soy flour - Contains approximately 50-54% protein 2
- Soy protein concentrate - Contains 65-70% protein, produced by removing flavor compounds and sugars from defatted soy flour 2
- Soy protein isolate (ISP) - Contains 90+% protein, the most refined form produced by alkali extraction 2
- Texturized vegetable protein (TVP) - Made from soy flour and concentrate, used in meat analogues 1
Nutritional Value of Soy Protein Foods
Protein Quality
- Soy protein is considered a complete protein containing all essential amino acids 3
- Mean Digestible Indispensable Amino Acid Score (DIAAS) for soy products is 84.5 ± 11.4 4
- Protein quality varies by processing method, with soymilk having the highest DIAAS among soy products 4
Nutritional Content of Common Soy Foods
| Food Item | Quantity | Protein (g) | Calories | Fiber (g) |
|---|---|---|---|---|
| Edamame | 1/2 cup (90g) | 11 | 126 | 4 |
| Tofu, firm | 79g | 7 | 70 | 1 |
| Soy burger | 1 patty (57g) | 13 | 60 | 3 |
| Soy milk | 1 cup (240ml) | 7 | 100 | 1 |
| Soy nuts | 1 oz (28g) | 12 | 120 | 5 |
| [1] |
Health Considerations
Cardiovascular Effects
- Earlier research suggested significant cholesterol-lowering effects of soy protein, but more recent studies show more modest benefits 1
- A very large amount of soy protein (more than half the daily protein intake) may lower LDL cholesterol by a few percentage points when replacing animal proteins 1
- Soy products like tofu, soy nuts, and some soy burgers can benefit cardiovascular health due to their high content of polyunsaturated fats, fiber, vitamins, and minerals, and low content of saturated fat 1
Other Health Effects
- Soy protein may have beneficial effects on obesity by potentially reducing body weight and fat mass 3
- The efficacy and safety of soy isoflavones for preventing or treating hormone-sensitive cancers are not established 1
Important Considerations When Choosing Soy Protein Foods
- Processing methods can affect protein quality and nutritional value 4
- Highly processed soy products may contain additives and higher sodium content 1
- Using soy foods to replace foods high in animal protein that contain saturated fat and cholesterol may confer cardiovascular health benefits 1
- Whole and minimally processed soy foods generally provide better overall nutritional profiles than highly processed versions 5
Soy protein foods offer a versatile plant-based protein option that can be incorporated into various dietary patterns, with traditional soy foods generally offering better nutritional profiles than highly processed alternatives.