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 certain foods or nutrients may contribute to conditions like obesity, diabetes, and heart disease. This field combines principles from epidemiology, which studies the distribution and determinants of health-related states, with knowledge of nutrition. By analyzing data from various populations, nutritional epidemiologists aim to identify dietary factors that can promote health and prevent disease, ultimately guiding public health recommendations.