Soy is a common food allergen, and there is a correlation of those who are intolerant to a food item as to those who are allergic to it. According to Eliot Herman, Ph.D., a researcher with the U.S. Department of Agriculture approximately 5 to 8 percent of children and 1 to 2 percent of adults are allergic to soy. According to the Food and Drug Administration, an estimated 0.2 percent of Americans are allergic to soy. The Food Allergen Labeling and Consumer Protection Act of 2004 lists soy as one of the eight most common food allergies.
While an allergy to soy would produce a measurable immune response, an intolerance to soy would not. If a food, such as soy, produces a significant amount of allergic reactions in a population, however, it is reasonable to suspect that there will be a corresponding number of individuals who are intolerant of the soy as well.