A system and method for identifying a potential trigger of an illness. Subject data including information about a subject, food consumption data including information about food consumed by the subject, and illness data including information about an illness experienced by the subject are forwarded to a server. The server also retrieves reference data indicating nutrient information for particular foods. The server determines the nutrients in each consumed food, determines various relative percentage weights for nutrients for times when an illness has been experienced, and outputs a report correlating experienced illness with consumed nutrients/foods. The server can also issue a report, based on the illness data, indicating whether particular medications are helpful in reducing the severity of illness. A report may also be generated to identify medication efficacy.