Which of the following is a common symptom of foodborne illness?

A common symptom of foodborne illness encompasses a range of distressing physical reactions, primarily characterized by fever and gastrointestinal distress. When individuals consume contaminated food or drink, their bodies often react with symptoms such as nausea, vomiting, diarrhea, and abdominal cramps, alongside the potential for fever as the immune system responds to the pathogens involved.

Gastrointestinal distress specifically refers to the discomfort and dysfunction in the digestive tract that can result from various pathogens, which can include bacteria, viruses, parasites, and toxins. Fever is a signal of the body's immune response aimed at fighting off these harmful entities.

The other choices presented do not accurately represent symptoms associated with foodborne illness. Increased appetite and improved digestion are typically not associated with foodborne pathogens and may even be considered opposite of what one would experience during such an illness. Therefore, the presence of fever and gastrointestinal distress is a critical indication of foodborne illness and reflects the body's response to infection or toxins.