Soy products are produced using soybeans, a common legume. The most common products with soy are edamame, tamari, teriyaki sauce, tofu, miso, soy flour, soy sauce, and tempeh. Soy is also an alternative to dairy, so there is also a soy version of cheese, yogurt, and ice cream. Many artificial flavorings, vegetable broths, vegetable gum, vegetable starches, and Asian dishes also include copious amounts of soy.
Soy products activate a cascade of immune components that are known to produce an allergic reaction. This cascade is what causes inflammation in many parts of the body. As the oral and nasal cavities are integral parts of an individual's immune system, these areas can become affected by the inflammation that occurs with the consumption of soy products. The cascade of white blood cells and the increased mucus production can exacerbate the existing obstructive tendencies of nasal polyps in an affected individual. Thus, their symptoms will worsen.