What is the most important constituent of commercially produced mushrooms?

The most important constituent of commercially produced mushrooms is water, making up about 90% of their composition. Additionally, they are rich in nutrients, including proteins, vitamins (especially B vitamins), minerals (such as selenium and potassium), and dietary fiber, which contribute to their health benefits and culinary versatility. The specific types of commercially produced mushrooms, such as button, shiitake, and oyster mushrooms, can vary in their nutrient profiles.