Nutritional epidemiology is the study of how diet and nutrition affect health and disease in populations. It examines the relationships between food intake, dietary patterns, and health outcomes, helping researchers understand how different nutrients and foods influence the risk of diseases such as obesity, diabetes, and heart disease. This field combines principles from epidemiology, which studies the distribution and determinants of health-related states, with nutrition science. By analyzing data from various populations, nutritional epidemiologists aim to identify dietary factors that contribute to health disparities and develop guidelines for healthier eating habits.