A nurse is educating a group of clients about the functions of protein. Which of the following information should the nurse include in the teaching?

Protein serves numerous essential physiological roles, one of the most important being support of immune function. Proteins form the structural basis of antibodies, cytokines, complement proteins, and other immune mediators; adequate dietary protein is therefore necessary for a competent immune response. This is a well-established function of dietary protein and is the correct answer. Carbohydrates, not protein, are the body's primary energy source; while protein can be catabolized for energy, this is not its primary role and occurs mainly during starvation or extreme stress. Stroke risk reduction is primarily associated with dietary factors such as reduced sodium intake, adequate potassium, and healthy fat choices — not specifically with protein intake. Preventing peptic ulcer disease is not a recognized function of dietary protein; peptic ulcers result from Helicobacter pylori infection, NSAIDs, or excess gastric acid, and diet modification alone does not prevent them. Understanding that protein promotes immune response helps clients appreciate why adequate protein intake is critical, particularly during illness or recovery.